Obscure gastrointestinal bleeding: diagnostic performance of 64-section multiphase CT enterography and CT angiography compared with capsule endoscopy

Objective:

To compare the diagnostic capabilities between capsule endoscopy (CE) and multislice CT (MSCT) enterography in combination with MSCT angiography for assessment of obscure gastrointestinal bleeding (OGIB).

Methods:

A total of 127 patients with OGIB were looked at in this study. 82 patients (aged 42.7 ± 19.1 years; 34 males) were assigned to receive MSCT diagnosis and 67 patients to (aged 53.9 ± 16.2 years; 28 males) receive CE diagnosis. Among them, 22 patients (aged 54.1 ± 19.1 years; 12 males) received both examinations. Oral isotonic mannitol and intramuscular injection of anisodamine were performed; non-ionic contrast (iopromide, 370 mg I ml⁻¹) was intravenously administered; and then multiphase scanning was conducted at arterial, small intestinal and portal venous phases in MSCT. The results were compared with findings of reference standards including double balloon enteroscopy, digital subtraction angiography, intraoperative pathological examination and/or clinical diagnosis.

Results:

Administration of anisodamine markedly increased the satisfaction rate of bowel filling (94.67% vs 28.57%; p < 0.001) but not the diagnostic yield (p = 0.293) of MSCT. Compared with MSCT, CE showed an improved overall diagnostic yield (68.66% vs 47.56%; p = 0.010), which was also observed in overt bleeding patients (i.e. patients with continued passage of visible blood) (76.19% vs 51.02%; p = 0.013) and in patients aged younger than 40 years of age (85% vs 51.28%; p = 0.024). However, CE had similar positive rates to MSCT (p > 0.05). Among the 22 cases in whom both examinations were conducted, CE showed no significantly different diagnostic capability compared with MSCT (p = 0.4597).

Conclusion:

Both CE and MSCT are safe and effective diagnostic methods for OGIB.

Advances in knowledge:

CE is preferred for overt bleeding or patients aged younger than 40 years. The combined use of CE and MSCT is recommended in OGIB diagnosis.Obscure gastrointestinal bleeding (OGIB), which accounts for approximately 5% of all gastrointestinal haemorrhage cases,¹ is defined as persistent or recurring gastrointestinal bleeding without an obvious aetiology after gastroduodenoscopy and colonoscopy.^2,3 Based on the presence or absence of clinically evident bleeding, OGIB could be divided into occult (no visible blood) and overt (continued passage of visible blood, such as haematemesis, melaena or haematochezia) bleeding.^3,4 OGIB frequently occurs in the small bowel and is caused by small bowel diseases such as intestinal erosions, ulcers, vascular anomaly, gastrointestinal tumours and inflammatory bowel and parasitic diseases.^5,6Multiple diagnostic techniques have been developed to elucidate the causes of OGIB. Among them, two non-invasive technologies, capsule endoscopy (CE) and multislice CT (MSCT) markedly improved the ability to determine the causes of OGIB by allowing the visualization of the gastrointestinal tract.^2,3,6 CE is able to obtain direct visualization of mucosal surface of the entire small intestine.^4,7,8 However, capsule retention remains a major risk of CE diagnosis.^4,9–11 In addition, the visual field restriction limits the value of CE in diagnosis of umbilicate or extraluminal lesions, since the small bowel is difficult to evaluate owing to its large length and tortuous course.^4,10 Conversely, MSCT, including MSCT angiography (MSCTA), MSCT enteroclysis and MSCT enterography (MSCTE), has full capacity to depict the extraintestinal lesions, owing to the combination of the advantages of enteral volume challenge with the ability of cross-sectional imaging.^4,12 Yet, substantial patient radiation exposure is one of the major disadvantages of MSCT diagnosis.^3,13 Careful preparation is also needed before examination.¹⁴ Considering that both CE and MSCT have advantages and disadvantages, a limited number of published data have compared the two diagnostic tools in patients with OGIB.^4,6,15–17 However, most of these studies did not refer to MSCTA, and apparently different results were obtained owing to the advancement of the two technologies. Thus, an updated and comprehensive comparison is required.Hence, we compared the diagnostic capability of MSCTE in combination with MSCTA with CE in patients suffering from OGIB. In this study, MSCTE and MSCTA technologies performed with a 64-slice spiral CT scanner were combined by non-contrast-enhanced scanning after oral administration of a neutral enteric contrast material (isotonic mannitol, 2.5%) and the intramuscular injection of anisodamine to restrain enterocinesia, and the following multiphase scanning at arterial, small intestinal and portal venous phases followed the intravenous infusion of non-ionic iodinated contrast material (iopromide, 370 mg I ml⁻¹). In addition, the influences of the clinical bleeding pattern and age on the diagnostic capability were also investigated.     

Lung ischaemia–reperfusion injury in a canine model: dual-energy CT findings with pathophysiological correlation

Objective:

To evaluate dual-energy CT (DECT) findings of pulmonary ischaemic–reperfusion injury (PIRI) and its pathophysiological correlation in the canine model.

Methods:

A PIRI model was established in 11 canines, utilizing closed pectoral balloon occlusion. Two control canines were also included. For the PIRI model, the left pulmonary artery was occluded with a balloon, which was deflated and removed after 2 h. DECT was performed before, during occlusion and at 2, 3 and 4 h thereafter and was utilized to construct pulmonary perfusion maps. Immediately after the CT scan at the fourth hour post reperfusion, the canines were sacrificed, and lung specimens were harvested for pathological analysis. CT findings, pulmonary artery pressure and blood gas results were then analysed.

Results:

Data at every time point were available for 10 animals (experimental group, n = 8; control group, n = 2). Quantitative measurements from DECT pulmonary perfusion maps found iodine attenuation values of the left lung to be the lowest at 2 h post embolization and the highest at 1 h post reperfusion. In the contralateral lung, perfusion values also peaked at 1 h post reperfusion. Continuous hypoxia and acid–based disorders were observed during PIRI, and comprehensive analysis showed physiological changes to be worst at 3 h post reperfusion.

Conclusion:

DECT pulmonary perfusion mapping demonstrated pulmonary perfusion of the bilateral lungs to be the greatest at 1 h post reperfusion. These CT findings corresponded with pathophysiological changes.

Advances in knowledge:

DECT pulmonary perfusion mapping can be used to evaluate lung ischaemia–reperfusion injury.Ischaemia–reperfusion injury (IRI) occurs under a variety of clinical conditions, including lung and/or cardiac transplantation, cardiopulmonary bypass, pulmonary resection, re-expansion pulmonary oedema, shock, cardiopulmonary resuscitation and pulmonary embolism.^1–3 Pulmonary embolism is a common cause of pulmonary IRI (PIRI), and the incidence of pulmonary embolism is increasing^4,5 with a mortality rate of up to 30%.⁶ With timely identification and treatment of pulmonary embolism, mortality rates can be reduced to <10%.⁷ However, reperfusion after treatment for lung ischaemia can also cause serious complications, such as haemorrhage and pulmonary oedema.⁸ Therefore, it is important to understand both the pathophysiological and imaging appearances of pulmonary IRI. Lung transplantation is also a common cause for PIRI following pulmonary arterial occlusion. Currently, the incidence of PIRI following transplantation is estimated at up to 25%. Post transplantation, PIRI can lead to insufficiency of the primary lung graft, delayed graft function, acute or chronic rejection (e.g. pulmonary oedema and acute respiratory failure), and increased early post-operative mortality and graft failure.^9,10CT is currently the predominant modality for the imaging assessment of thoracic disorders, including PIRI. Dual-energy CT (DECT) allows simultaneous acquisition of dual-energy data sets, allowing for decomposition of the scanned entity based on differences in attenuation between air, soft tissue and iodine.¹¹ One application of this principle in pulmonary imaging is the ability to obtain iodine maps demonstrating the distribution of pulmonary perfusion. The use of CT perfusion mapping has been shown to be relatively sensitive and highly specific for the detection of pulmonary emboli.¹²Recent research into PIRI has focused on the pathological and molecular biological mechanisms.^13–16 To date, there are few reports on imaging and pathophysiological findings in PIRI.^17,18 CT perfusion findings in PIRI have also not yet been described. The aim of this study was to assess PIRI imaging and pathophysiological findings in a canine model.     

Diffusion-weighted MRI in the follow-up of chronic periaortitis

Objective:

To evaluate the usefulness of diffusion-weighted MRI (DWI) for the assessment of the intraindividual follow-up in patients with chronic periaortitis (CP) under medication.

Methods:

MRI data of 21 consecutive patients with newly diagnosed untreated disease were retrospectively examined before and after medical therapy, with a median follow-up of 16 weeks. DWI parameters [b800 signal, apparent diffusion coefficient (ADC) values] of the CP and psoas muscle were analysed together with the extent and contrast enhancement. Pre- and post-treatment laboratory inflammation markers were acquired parallel to each MR examination.

Results:

Statistically significant lower b800 signal intensities (p ≤ 0.0001) and higher ADC values (p ≤ 0.0001) were observed after medical treatment within the fibrous periaortic tissue. Extent and contrast enhancement of the CP showed also a statistically significant decrease (p ≤ 0.0001) in the follow-up examinations, while the control parameters within the psoas muscle showed no differences.

Conclusion:

DWI seems to be a useful method for the evaluation of response to treatment without contrast agents. The technique may be helpful in the assessment of disease activity to guide further therapeutic strategies.

Advances in knowledge:

DWI detects significant differences in the intraindividual follow-up of CP under medical therapy.Chronic periaortitis (CP) is a proliferating fibroinflammatory disease of the perivascular retroperitoneal space and aortic wall.^1–4 Owing to adventitial inflammation, some recent theories consider CP as a large vessel vasculitis.⁵ Clinical manifestations of CP include idiopathic retroperitoneal fibrosis, inflammatory aortic aneurysm and perianeurysmal retroperitoneal fibrosis.^2,6,7 The three manifestations with very similar histopathological characteristics are distinguished by the diameter of the abdominal aorta and concomitant ureteral affection.^1,3,7Specific clinical symptoms are caused by extrinsic compression of the ureters or retroperitoneal veins, resulting in hydronephrosis, oliguria, lower extremity oedema and deep vein thrombosis.^1,8Under medical treatment with steroids, CP has a good prognosis.⁷ Today tamoxifen is suggested as a safe and effective therapeutic alternative, and immunosuppressive drugs can be considered in patients with suboptimal responses to these drugs or multiple relapses.^9–11CT and MRI are the modalities of first choice for diagnosis and follow-up of CP.^1,7,12 The fibrotic para-aortic tissue shows significant contrast uptake in gadolinium-enhanced MRI.^12–14 Dynamic contrast-enhanced MRI was suggested for the assessment of the disease activity.^15,16 However, in cases with impaired renal function (e.g. by ureteral compression), gadolinium-independent imaging methods should be preferred owing to the potential development of a nephrogenic systemic fibrosis.¹⁷Diffusion-weighted MRI (DWI) is a non-contrast MR modality that has been successfully applied for the assessment of retroperitoneal masses, inflammatory abdominal aortic aneurysms and for the differentiation between retroperitoneal fibrosis and malignant retroperitoneal neoplasms.^18–21DWI indicates restricted diffusion of water, for example caused by a high cellularity in malignant disease or active inflammation. The apparent diffusion coefficient (ADC) is a quantitative parameter for the level of restricted diffusion, which is calculated from the signals of different diffusion gradients (b-values).²²In the context of untreated CP diffusion-weighted MRI may detect restricted inflammation as a sign of high cellularity caused by active inflammation.There are no data for the evaluation of intraindividual follow-up and the response to treatment by DWI of CP so far. Therefore, the aim of the present study was to analyse differences in DWI signals during follow-up in patients with CP before and after treatment. In addition, we sought to elucidate the potential of DWI in the therapy monitoring of CP.     

Femoral neck shaft angle width is associated with hip-fracture risk in males but not independently of femoral neck bone density

Objective:

To investigate the specificity of the neck shaft angle (NSA) to predict hip fracture in males.

Methods:

We consecutively studied 228 males without fracture and 38 with hip fracture. A further 49 males with spine fracture were studied to evaluate the specificity of NSA for hip-fracture prediction. Femoral neck (FN) bone mineral density (FN-BMD), NSA, hip axis length and FN diameter (FND) were measured in each subject by dual X-ray absorptiometry. Between-mean differences in the studied variables were tested by the unpaired t-test. The ability of NSA to predict hip fracture was tested by logistic regression.

Results:

Compared with controls, FN-BMD (p < 0.01) was significantly lower in both groups of males with fractures, whereas FND (p < 0.01) and NSA (p = 0.05) were higher only in the hip-fracture group. A significant inverse correlation (p < 0.01) was found between NSA and FN-BMD. By age-, height- and weight-corrected logistic regression, none of the tested geometric parameters, separately considered from FN-BMD, entered the best model to predict spine fracture, whereas NSA (p < 0.03) predicted hip fracture together with age (p < 0.001). When forced into the regression, FN-BMD (p < 0.001) became the only fracture predictor to enter the best model to predict both fracture types.

Conclusion:

NSA is associated with hip-fracture risk in males but is not independent of FN-BMD.

Advances in knowledge:

The lack of ability of NSA to predict hip fracture in males independent of FN-BMD should depend on its inverse correlation with FN-BMD by capturing, as the strongest fracture predictor, some of the effects of NSA on the hip fracture. Conversely, NSA in females does not correlate with FN-BMD but independently predicts hip fractures.Hip fracture is the worst osteoporotic fracture with regard to cost^1,2 and adverse consequences,^3,4 so its prevention by checking for the related fracture risk factors is an important goal. Although low bone mineral density (BMD) is generally recognized as the main risk factor for hip fracture,^5,6 there is growing evidence that other bone characteristics, such as proximal femur geometry (PFG) parameters, are implicated in determining the risk profile for hip fracture.^7,8 This evidence, however, mainly derives from studies carried out in females,^9–13 whereas contradictory results characterize studies carried out in males.^14–20 Authors'' opinions seem to vary widely about the ability of the neck shaft angle (NSA), one of the PFG factors, to predict osteoporotic hip fractures in males,^14–16,21 whereas its association with the risk of hip fracture in females^10,11,14,22 is generally accepted. Gender differences in the hip anatomy²³ have been put forward as a possible explanation for the different relationship of NSA with the hip-fracture risk between genders, whereas geographic and racial differences²⁴ among the examined male populations have been advocated as a possible cause of authors'' discrepancies on the relationship between NSA and the hip-fracture risk in males.This topic is therefore still under debate, and further studies are required to clarify the association of the NSA with hip-fracture risk in males. The authors of the current study contribute to this topic by studying the relationship between NSA and the hip fragility fracture in a sample of white Italian males.     

Multidetector CT imaging features of solid pseudopapillary tumours of the pancreas in male patients: distinctive imaging features with female patients

Objective:

To describe multidetector CT imaging features of solid pseudopapillary tumours (SPTs) in male patients and to compare these imaging features with those found in female patients.

Methods:

The institutional review board approved this retrospective study. We included the CT images of 72 patients (M:F = 12:60; mean age, 35.0 years) diagnosed with SPT by histology. CT images were reviewed on the following: location of the tumour, maximal diameter, shape, margin and the fraction of the tumour composition. Statistical differences in CT imaging features were analysed.

Results:

Male patients with SPTs were significantly older than female patients (42.4 years vs 33.4 years, p = 0.0408) and the mean size of the SPTs in male patients was larger (6.3 cm vs 4.6 cm, p = 0.0413) than that of SPTs in female patients. Lobulated shape of the SPTs was most frequent in male patients, whereas oval shape was most frequent in female patients (p = 0.0133). SPTs in male patients tended to have a solid component (p = 0.0434). Progressive enhancement in the solid portion of the tumour was seen in 9 (81.8%) of 11 SPTs in male patients and in 30 (79.0%) of 38 SPTs in female patients on multiphasic CT.

Conclusion:

The imaging features of SPTs in male patients usually appeared as a somewhat large-sized solid mass with a lobulated margin and progressive enhancement. These imaging features may help to differentiate SPTs from other pancreatic tumours for their proper management.

Advances in knowledge:

SPTs in male patients appear as somewhat large-sized solid masses with lobulated margins, and this form occurs more frequently in older male patients than in female patients.Solid pseudopapillary tumour (SPT) of the pancreas is a rare low-grade malignant neoplasm accounting for only 1–2% of all pancreatic tumours.^1–3 Synonyms for this neoplasm include solid and cystic tumours, solid and papillary epithelial neoplasms, solid cystic papillary tumour, papillary cystic neoplasm, papillary cystic epithelial neoplasm, papillary cystic tumour or Frantz''s tumour.^3,4SPT is known to occur preferentially in young females and has a favourable prognosis. The characteristic imaging features of SPTs include encapsulation, solid and cystic components and peripheral calcification.^1,3,4 Although the imaging characteristics of SPTs have been well described in recent years,^3,5 it remains uncertain if the features of SPT occurring in males differ from those in females.Machado et al⁶ and Takahashi et al⁷ described distinctive clinicopathological characteristics of SPTs occurring in males. The purpose of this study was to describe multidetector CT (MDCT) imaging features of SPTs in male patients and to compare these features with those of female patients.     

Comparative study of hepatic venography using non-linear-blending images,monochromatic images and low-voltage images of dual-energy CT

Objective:

To investigate the use of non-linear-blending and monochromatic dual-energy CT (DECT) images to improve the image quality of hepatic venography.

Methods:

82 patients undergoing abdominal DECT in the portal venous phase were enrolled. For each patient, 31 data sets of monochromatic images and 7 data sets of non-linear-blending images were generated. The data sets of the non-linear-blending and monochromatic images with the best contrast-to-noise ratios (CNRs) for hepatic veins were selected and compared with the images obtained at 80 kVp and a simulated 120 kVp. The subjective image quality of the hepatic veins was evaluated using a four-point scale. The image quality of the hepatic veins was analysed using signal-to-noise ratio (SNR) and CNR values.

Results:

The optimal CNR between hepatic veins and the liver was obtained with the non-linear-blending images. Compared with the other three groups, there were significant differences in the maximum CNR, the SNR, the subjective ratings and the minimum background noise (p < 0.001). A comparison of the monochromatic and 80-kVp images revealed that the CNR and subjective ratings were both improved (p < 0.001). There was no significant difference in the CNR or subjective ratings between the simulated 120-kVp group and the control group (p = 0.090 and 0.053, respectively).

Conclusion:

The non-linear-blending technique for acquiring DECT provided the best image quality for hepatic venography.

Advances in knowledge:

DECT can enhance the contrast of hepatic veins and the liver, potentially allowing the wider use of low-dose contrast agents for CT examination of the liver.CT venography (CTV) is an important non-invasive examination to assess the hepatic veins and plays an important role in the pre-operative evaluation of liver transplants and the diagnosis of hepatic venous diseases.^1,2 Compared with CT hepatic artery angiography or multiphasic liver CT, CTV often requires a larger dose of the contrast agent to achieve sufficient contrast for filling in the hepatic veins.³ Increasing the contrast agent not only increases the economic burden of the patient but also raises the incidence of side effects and complications related to the contrast agent. One of the goals in the advancement of CT techniques is to continuously improve the image quality and clinical applications while reducing radiation exposure and promoting the reasonable use of contrast agents. Several studies suggest that low tube voltage CTV reduces radiation and improves vascular contrast^4–6 because iodinated contrast material is more conspicuous in low-kilovolt peak(kVp) images with an approximately 80% increase in CT attenuation at 80 kVp compared with that at 140 kVp.^6–8Dual-source CT (DSCT) was recently introduced into clinical practice. It can simultaneously acquire low- and high-energy image data using two X-ray tube and detector systems mounted in one gantry.⁹ Dual-energy CT (DECT) could improve the contrast and thereby the image quality of CTV images by virtual monochromatic imaging¹⁰ and non-linear-blending⁸ and linear-blending techniques.^7,11,12 Studies have shown that a DECT non-linear-blending technique could improve the conspicuity of myocardial delayed enhancement.⁸ The clinical application of DSCT undoubtedly greatly aides the choice of a suitable application from a variety of post-processing techniques that can significantly improve the contrast enhancement of hepatic veins. However, the ability to improve the conspicuity of hepatic veins via a dual-source DECT non-linear-blending technique and the performance of non-linear-blending and monochromatic imaging techniques have not been studied. Therefore, the purpose of our study was to improve the image quality of hepatic venography over single-energy CT by using DECT virtual monochromatic imaging and a non-linear-blending technique.     

Walking on thin ice! Identifying methamphetamine “drug mules” on digital plain radiography

Objective:

The purpose of this study was to retrospectively evaluate the sensitivity, specificity and accuracy of identifying methamphetamine (MA) internal payloads in “drug mules” by plain abdominal digital radiography (DR).

Methods:

The study consisted of 35 individuals suspected of internal MA drug containers. A total of 59 supine digital radiographs were collected. An overall calculation regarding the diagnostic accuracy for all “drug mules” and a specific evaluation concerning the radiological appearance of drug packs as well as the rate of clearance and complications in correlation with the reader''s experience were performed. The gold standard was the presence of secured drug packs in the faeces.

Results:

There were 16 true-positive “drug mules” identified. DR of all drug carriers for Group 1 (forensic imaging experienced readers, n = 2) exhibited a sensitivity of 100%, a mean specificity of 76.3%, positive predictive value (PPV) of 78.5%, negative predictive value (NPV) of 100% and a mean accuracy 87.2%. Group 2 (inexperienced readers, n = 3) showed a lower sensitivity (93.7%), a mean specificity of 86%, a PPV of 86.5%, an NPV of 94.1% and a mean accuracy of 89.5%. The interrater agreement within Group 1 was 0.72 and within Group 2 averaged to 0.79, indicating a fair to very good agreement.

Conclusion:

DR is a valuable screening tool in cases of MA body packers with huge internal payloads being associated with a high diagnostic insecurity. Diagnostic insecurity on plain films may be overcome by low-dose CT as a cross-sectional imaging modality and addressed by improved radiological education in reporting drug carriers on imaging.

Advances in knowledge:

Diagnostic signs (double-condom and halo signs) on digital plain radiography are specific in MA “drug mules”, although DR is associated with high diagnostic insecurity and underreports the total internal payload.For the past decade, significant worldwide manufacturing of amphetamine-type stimulants has been reported to the United Nations Office on Drugs and Crime, Vienna, Austria, with a predominance of methamphetamine (MA) and its derivatives, which are also known as “syabu” or “ice”, throughout East and South East Asia.¹ In this region, the use of this synthetic drug is more prevalent than that of cocaine or heroin, which are more common in relatively developed areas, such as Europe and the USA.² During the course of this development, an increase in the number of drug carriers being intercepted by law enforcement at the borders of Malaysia has been observed. Drug carriers or “drug mules” are generally referred to as a human harbouring internal illicit drug packet(s). Internal body concealment of illegal drugs is one of the methods used to smuggle this illicit drug across the border.^3,4 “Drug mules” are generally known as body packers.^5,6 However, for correct terminology, one should differentiate between the terms body packer, body pusher and body stuffer. A body packer swallows a large amount of specially prepared drug packets to smuggle the packets in their gastrointestinal tract across a national border.^5,6 A body pusher hides a few containers in easily accessible body cavities, such as the rectum or vagina. Body stuffers, including traffickers and users, ingest intentionally small amounts of loosely wrapped drug pellets (typically initially hidden in the mouth), usually immediately before an unexpected encounter with law enforcement.^5–10The generally accepted radiological examination is a plain abdominal radiograph in the supine projection.^4–6 This technique is widely available at a low cost and is a simple method of detecting drug-filled packets within the alimentary tract. Radiation exposure to the patient is relatively moderate. In the literature, the detection rate for drug-filled packets is highly variable, and sensitivities from 58.3% to 90% have been reported.^4,5,11 Hence, plain abdominal radiography is a flawed screening method for identifying “drug mules”. Examining the bowel for foreign bodies, such as drug containers with variable sizes and radiodensities, is problematic, even for an experienced radiologist because the drug-filled packets may have an appearance similar to that of stool and gas and may be superimposed. Specific appearances described in the literature, such as the “double-condom”, “halo” and “rosette” signs, may be diagnostic for drug packages but are not necessarily so.^{4–6,11–13} Other modalities employed worldwide for the identification of body packers include CT, ultrasound, MRI and low-dose linear slit digital radiography (LSDR or LODOX®; Lodox Systems, Johannesburg, South Africa).^4,5,14–18Recent research has mainly concentrated on cocaine and heroin drug trafficking, which occurs predominantly in Western countries.^{3,4,6,7,11,14,19} There is little research on the accuracy of plain abdominal radiography in MA drug carriers, although there has been a significant increase of MA in Asia, accompanied by draconian legal measures in cases of drug trafficking.^1,2 The purpose of this study was to retrospectively evaluate the sensitivity, specificity and accuracy of plain abdominal digital radiography (DRL) for identifying the internal payloads of MA in “drug mules”.     

Whole-body CT-based imaging algorithm for multiple trauma patients: radiation dose and time to diagnosis

Objective:

To determine the number of imaging examinations, radiation dose and the time to complete trauma-related imaging in multiple trauma patients before and after introduction of whole-body CT (WBCT) into early trauma care.

Methods:

120 consecutive patients before and 120 patients after introduction of WBCT into the trauma algorithm of the University Hospital Zurich were compared regarding the number and type of CT, radiography, focused assessment with sonography for trauma (FAST), additional CT examinations (defined as CT of the same body regions after radiography and/or FAST) and the time to complete trauma-related imaging.

Results:

In the WBCT cohort, significantly more patients underwent CT of the head, neck, chest and abdomen (p < 0.001) than in the non-WBCT cohort, whereas the number of radiographic examinations of the cervical spine, chest and pelvis and of FAST examinations were significantly lower (p < 0.001). There were no significant differences between cohorts regarding the number of radiographic examinations of the upper (p = 0.56) and lower extremities (p = 0.30). We found significantly higher effective doses in the WBCT (29.5 mSv) than in the non-WBCT cohort (15.9 mSv; p < 0.001), but fewer additional CT examinations for completing the work-up were needed in the WBCT cohort (p < 0.001). The time to complete trauma-related imaging was significantly shorter in the WBCT (12 min) than in the non-WBCT cohort (75 min; p < 0.001).

Conclusion:

Including WBCT in the initial work-up of trauma patients results in higher radiation doses, but fewer additional CT examinations are needed, and the time for completing trauma-related imaging is shorter.

Advances in knowledge:

WBCT in trauma patients is associated with a high radiation dose of 29.5 mSv.CT represents an important imaging modality in the evaluation of trauma patients and traditionally was performed after an initial evaluation with conventional radiography and sonography. Owing to technical developments, whole-body CT (WBCT) became feasible, which led to its integration into the early work-up of patients.^1–5 A recent retrospective multicentre study suggested that the use of WBCT as the primary imaging modality would significantly increase the probability of survival in patients with multiple trauma compared with an imaging algorithm using radiography, sonography, eventually followed by CT of selected body regions.⁶ Thus, WBCT was recommended by various authors as the primary diagnostic method for trauma patients,^7,8 even when such patients are borderline haemodynamically unstable.^2,9–11However, the true benefit of WBCT remains a matter of debate. A recent systematic review demonstrated that it is still not determined whether the benefit in terms of decreased mortality is a true effect of WBCT or is mediated through changes in the management of trauma patients.¹² Another relevant issue is the associated radiation dose of CT, in particular when employing WBCT.¹² Interestingly, most previous studies did not determine radiation doses of WBCT but rather provided estimates or extrapolations,^6,13–15 and no study, to our knowledge, directly compared radiation doses of patients with multiple trauma undergoing radiography and selected CT with those undergoing WBCT, taking into account the additional CT imaging that was necessary for completing the trauma-related imaging work-up if radiography and sonography were not sufficient.Thus, the purpose of our study was to assess the number of radiological investigations and radiation doses in the initial imaging evaluation of patients with multiple trauma before and after the introduction of WBCT into early trauma care in our hospital. Furthermore, we determined the time from the patients'' admission to the completion of trauma-related diagnostic work-up.     

The challenge of segmental small bowel motility quantitation using MR enterography

Objective:

Analysis of “cine” MRI using segmental regions of interest (ROIs) has become increasingly popular for investigating bowel motility; however, variation in motility in healthy subjects both within and between scans remains poorly described.

Methods:

20 healthy individuals (mean age, 28 years; 14, males) underwent MR enterography to acquire dynamic motility scans in both breath hold (BH) and free breathing (FB) on 2 occasions. Motility data were quantitatively assessed by placing four ROIs per subject in different small bowel segments and applying two measures: (1) contractions per minute (CPM) and (2) Jacobian standard deviation (SD) motility score. Within-scan (between segment) variation was assessed using intraclass correlation (ICC), and repeatability was assessed using Bland–Altman limits of agreement (BA LoA).

Results:

Within-scan segmental variation: BH CPM and Jacobian SD metrics between the four segments demonstrated ICC R = 0.06, p = 0.100 and R = 0.20, p = 0.027 and in FB, the CPM and Jacobian SD metrics demonstrated ICC R = −0.26, p = 0.050 and R = 0.19, p = 0.030. Repeatability: BH CPM for matched segments ranged between 0 and 14 contractions with BA LoA of ±8.36 and Jacobian SD ranged between 0.09 and 0.51 with LoA of ±0.33. In FB data, CPM ranged between 0 and 10 contractions with BA LoA of ±7.25 and Jacobian SD ranged between 0.16 and 0.63 with LoA = ±0.28.

Conclusion:

The MRI-quantified small bowel motility in normal subjects demonstrates wide intersegmental variation and relatively poor repeatability over time.

Advances in knowledge:

This article presents baseline values for healthy individuals of within- and between-scan motility that are essential for understanding how this process changes in disease.Dynamic “cine” MRI acquired during MR enterography is increasingly utilized to assess bowel motility in a range of conditions, notably inflammatory bowel disease and enteric dysmotility syndromes.^1–4 Analysis of the data remains primarily subjective in clinical routine, but the ability to apply quantitative techniques makes this a potentially powerful methodology to explore gastrointestinal physiology in disease as well as an emerging application as a biomarker for drug efficacy.^5–7Despite the growing literature, a consensus has yet to be reached as to the best method of quantitatively analysing small bowel data and indeed a range of motility metrics are proposed.^2,3,8–12 The most commonly used metric is the change in luminal diameter at a fixed anatomical position through the time series. By tracking bowel diameter, a characteristic curve can be produced with the number of contractions expressed per minute (CPM) to give an intuitive and broadly accepted metric for small bowel motility (SBM).^{2–4,9,11,13–15} To date, several studies have reported a relationship between CPM and dysmotility in disease, either compared with a histopathological standard or “normal” reference bowel loops.^2–4,12 An array of additional metrics derived both from bowel diameter measures and more abstract processing techniques have further been implemented with varying degrees of effectiveness in disease and health.^{2,4,5,8,10,14,16}Although intuitively attractive, the robustness of assessing overall enteric motility using only an isolated loop of bowel has received relatively little attention to date irrespective of the precise metric applied. It is unclear how representative the selected bowel loops are of overall SBM and if normal motility intrinsically differs between bowel segments, for example, between the jejunum and ileum. Furthermore, the repeatability of single loop metrics, even in normal individuals, is not well described, knowledge of which is vital if segmental analysis is to be used to diagnose, guide treatment and monitor enteric pathology.The purpose of this study is to explore segmental variation in SBM in healthy volunteers measured using two commonly reported small bowel metrics [CPM and Jacobian standard deviation (SD)] looking at (1) within-scan motility variation between different segments and (2) between-scan variation (repeatability) across two time points.     

Diffusion-weighted imaging vs STIR turbo SE imaging: capability for quantitative differentiation of small-cell lung cancer from non-small-cell lung cancer

Objective:

To compare the capability of differentiation of small-cell lung cancer (SCLC) from non-SCLC (NSCLC) between diffusion-weighted imaging (DWI) and short tau inversion recovery (STIR) turbo spin-echo imaging.

Methods:

The institutional review board of Kobe University Hospital, Kobe, Japan, approved this study, and written informed consent was obtained from each patient. 49 patients with NSCLC (30 males and 19 females; mean age, 66.8 years) and 7 patients with SCLC (5 males and 2 females; mean age, 68.6 years) enrolled and underwent DWI and STIR. To quantitatively differentiate SCLC from NSCLC, apparent diffusion coefficient (ADC) values on DWI and contrast ratios (CRs) between cancer and muscle on STIR were evaluated. ADC values and CRs were then compared between the two cell types by Mann–Whitney''s U-tests, and the diagnostic performances were compared by McNemar''s test.

Results:

There were significant differences of mean ADC values (p < 0.001) and mean CRs (p = 0.003). With adopted threshold values, the specificity (85.7%) and accuracy (85.7%) of DWI were higher than those of STIR (specificity, 63.3%; p = 0.001 and accuracy, 66.1%; p = 0.001). In addition, the accuracy of combination of both indexes (94.6%; p = 0.04) could significantly improve as compared with DWI alone.

Conclusion:

DWI is more useful for the differentiation of SCLC from NSCLC than STIR, and their combination can significantly improve the accuracy in this setting.

Advances in knowledge:

Pulmonary MRI, including DWI and STIR, had a potential of the suggestion of the possibility as SCLC.Lung cancer is the most common cause of cancer-related death among both males and females worldwide.¹ Lung cancers are divided into non-small-cell cancer (NSCLC) and small-cell lung cancer (SCLC), and the differentiation between SCLC and NSCLC is important in clinical practice because their therapeutic strategies, clinical course and prognoses are different.² In general, SCLC is usually determined with extensive hilar and mediastinal lymphadenopathy,³ and these cancers are mainly treated by chemotherapy or chemoradiotherapy.^2,4On the other hand, 5–10% of patients with SCLC were diagnosed as having solitary pulmonary nodules.^5,6 In this situation, the assessments of distant metastases before treatment play an important role in deciding the treatment. At present, although there are some different reports for patients with NSCLC regarding the assessment of distant metastases before surgery,^7–9 it is important to assess the distant metastases of these patients with SCLC because SCLC is known for its rapid doubling time, high growth fraction and early development of metastatic disease.^10–12 If patients with SCLC are diagnosed at Stage I or possibly Stage II, clinicians consider their treatment as surgery and/or neoadjuvant chemotherapy.^13–15 Therefore, the differentiation between SCLC and NSCLC and the suggestion of the possibility of SCLC may be important in routine clinical practice. However, the differentiation of SCLC from NSCLC is difficult on CT and positron emission tomography (PET) or PET/CT,^5,6,16 and fiberoptic bronchoscopy and percutaneous biopsy are recommended, although their diagnostic sensitivities range from 67% to 100%.^17–19Recently, the image quality and diagnostic capability of chest MRI has improved because of the advancement of MR systems and sequences, and short tau inversion recovery (STIR) turbo spin-echo (SE) imaging and diffusion-weighted imaging (DWI) have been reported as useful in differentiating malignant nodules and lymph nodes from benign ones in several articles.^20–25 Meanwhile, the utilities of chest MRI, including STIR and DWI, have been reported,²⁶ and, in addition, meta-analysis report for pulmonary nodules by means of DWI have been published.²⁷ However, to the best of our knowledge, there have been only reports of chest DWI regarding the differentiation between SCLC and NSCLC,²² but no major studies have reported a direct comparison of the use of DWI and STIR in chest MRI for the assessment of differentiation between SCLC and NSCLC. We hypothesized that both DWI and STIR were useful MR sequences for differentiation of SCLC from NSCLC and their combination might improve the differentiation capabilities. The aim of this study was to evaluate the diagnostic performances of DWI and STIR for differentiating between SCLC and NSCLC.     

Primary vaginal cancer: role of MRI in diagnosis,staging and treatment

Primary carcinoma of the vagina is rare, accounting for 1–3% of all gynaecological malignancies. MRI has an increasing role in diagnosis, staging, treatment and assessment of complications in gynaecologic malignancy. In this review, we illustrate the utility of MRI in patients with primary vaginal cancer and highlight key aspects of staging, treatment, recurrence and complications.The incidence of primary vaginal cancer increases with age, with approximately 50% of patients presenting at age greater than 70 years and 20% greater than 80 years.¹ Around 2890 patients are currently diagnosed with vaginal carcinoma in the USA each year, and almost 30% die of the disease.² The precursor for vaginal cancer, vaginal intraepithelial neoplasia (VAIN) and invasive vaginal cancer is strongly associated with human papillomavirus (HPV) infection (93%).^3,4 In situ and invasive vaginal cancer share many of the same risk factors as cervical cancer, such as tobacco use, younger age at coitarche, HPV and multiple sexual partners.^5–7 In fact, higher rates of vaginal cancer are observed in patients with a previous diagnosis of cervical cancer or cervical intraepithelial neoplasia.^7,8As is true for other gynaecologic malignancies, vaginal cancer diagnosis and staging rely primarily on clinical evaluation by the International Federation of Gynecology and Obstetrics (FIGO).⁹ Pelvic examination continues to be the most important tool for evaluating local extent of disease, but this method alone is limited in its ability to detect lymphadenopathy and the extent of tumour infiltration. Hence, FIGO encourages the use of imaging. Fluorine-18 fludeoxyglucose-positron emission tomography (¹⁸F-FDG-PET), a standard imaging tool for staging and follow-up in cervical cancer, can also be used for vaginal tumours, with improved sensitivity for nodal involvement compared to CT alone.¹⁰ In addition to staging for nodal and distant disease, CT [simulation with three dimensional (3D) conformations] is particularly useful for treatment planning and delivery of external beam radiation. MRI, with its excellent soft tissue resolution, is commonly used in gynaecologic malignancies and has been shown to be accurate in diagnosis, local staging and spread of disease in vaginal cancer.^11,12 While no formal studies are available for vaginal cancer, in cervical cancer MRI actually alters the stage in almost 30% of patients.^13–15Treatment planning in primary vaginal cancer is complex and requires a detailed understanding of the extent of disease. Because vaginal cancer is rare, treatment plans remain less well defined, often individualized and extrapolated from institutional experience and outcomes in cervical cancer.^1,16–19 There is an increasing trend towards organ preservation and treatment strategies based on combined external beam radiation and brachytherapy, often with concurrent chemotherapy,^14,20,21 surgery being reserved for those with in situ or very early-stage disease.²² Increasing utilization of MR may provide superior delineation of tumour volume, both for initial staging and follow-up, to allow for better treatment planning.²³     

Use of 99mTc-doxorubicin scintigraphy in females with breast cancer: a pilot study

Objective:

Doxorubicin (Eurofarma, São Paulo, Brazil) is an antitumour agent widely used in the treatment of breast cancer and can be used for tumour tracking when labelled with a radionuclide. Here, we present the results obtained with technetium-99m (^99mTc)-doxorubicin, using the direct method, to evaluate its uptake in breast cancer.

Methods:

Four females with confirmed breast carcinoma diagnosis and breast image reporting and data system Category 5 on mammography underwent whole-body and thorax single-photon emission CT/CT imaging 1 and 3 h after ^99mTc-doxorubicin administration.

Results:

We observed increased uptake in breast carcinoma lesions and elimination via renal and hepatic pathways.

Conclusion:

These preliminary results suggest that ^99mTc-doxorubicin may be a promising radiopharmaceutical for the evaluation of patients with breast cancer. Further studies are ongoing.

Advances in knowledge:

To our knowledge, this is the first study to evaluate the use of a directly labelled doxorubicin tracer in humans. ^99mTc-doxorubicin could provide information on the response of tumours to doxorubicin.Breast cancer is the most common cancer in females worldwide, with an estimated 1.67 million new cases in 2012.¹ In order to improve the treatment and prognosis of breast cancer, early detection is extremely important. However, the techniques most often used for cancer evaluation, such as mammography, ultrasonography and MRI, have limitations and are not always capable of differentiating benign from malignant lesions. Breast scintigraphy has some clinical indications and, in association with other imaging methods, can increase the accuracy of diagnoses and reduce unnecessary biopsies.²Advances in imaging modalities have contributed to the improvement of early breast cancer diagnosis.³ The use of positron emission tomography (PET) and its new radiopharmaceuticals is an important advance in cancer detection.⁴ Hybrid acquisition of PET with CT (PET/CT) allows evaluation of morphological parameters, increasing the sensitivity and specificity of PET findings.⁴ However, the uptake of fluorine-18-fludeoxyglucose (¹⁸F-FDG), the radiopharmaceutical most often used for PET, changes according to different variables, such as the histological type. In breast cancer, infiltrating ductal carcinoma shows higher uptake than infiltrating lobular carcinoma, while in ductal carcinoma, uptake is usually low.^{5–7 18}F-FDG uptake also depends on the grade of breast cancer.^6,8 Hybrid PET/CT has low sensitivity for tumours <1 cm, owing to limitations in spatial resolution and tumour variables,^7,8 and ¹⁸F-FDG uptake may occur in benign lesions such as inflammatory granulomatous mastitis.⁹ Although PET/CT is limited in the evaluation of tumour size and the presence of multifocal disease, this might change with the advent of positron emission mammography (PEM). Eo et al¹⁰ reported that PEM diagnosed more malignant breast lesions than PET/CT, particularly in tumours <2 cm.Unfortunately, PET scanners are not available in all nuclear medicine services, notably in developing countries. Conventional gamma cameras, on the other hand, are widely available and therefore single-photon emission CT (SPECT) radiopharmaceuticals have the potential to benefit a larger number of patients. Another promising tool is the use of dedicated apparatus for conventional nuclear medicine of the breast, called molecular breast imaging (MBI), which can detect malignant breast lesions <1 cm.^11,12Doxorubicin (Eurofarma, São Paulo, Brazil) is a potent antitumour agent that is widely used in chemotherapy for several types of cancer.¹³ It acts by intercalating nucleotide bases, binding to the lipid membrane, and also inhibits the biosynthesis of macromolecules.¹⁴ Among the main side effects of this drug is possible cardiotoxicity.¹⁵ Technetium-99m (^99mTc) is the radionuclide most often used in conventional nuclear medicine; our research group has used ^99mTc to radiolabel different types of cells and molecules.^16–23 We previously reported a technique for labelling the thymidine precursor thymine with ^99mTc, with good specificity and high predictive value.^16–18 We have also used ^99mTc-doxorubicin in dogs and cats in order to evaluate its uptake in different kinds of tumours, with promising results, which led to the approval of this pilot trial.²⁴     

Low kV settings CT angiography (CTA) with low dose contrast medium volume protocol in the assessment of thoracic and abdominal aorta disease: a feasibility study

Objective:

To assess the diagnostic quality of low dose (100 kV) CT angiography (CTA), by using ultra-low contrast medium volume (30 ml), for thoracic and abdominal aorta evaluation.

Methods:

67 patients with thoracic or abdominal vascular disease underwent multidetector CT study using a 256 slice scanner, with low dose radiation protocol (automated tube current modulation, 100 kV) and low contrast medium volume (30 ml; 4 ml s⁻¹). Density measurements were performed on ascending, arch, descending thoracic aorta, anonymous branch, abdominal aorta, and renal and common iliac arteries. Radiation dose exposure [dose–length product (DLP)] was calculated. A control group of 35 patients with thoracic or abdominal vascular disease were evaluated with standard CTA protocol (automated tube current modulation, 120 kV; contrast medium, 80 ml).

Results:

In all patients, we correctly visualized and evaluated main branches of the thoracic and abdominal aorta. No difference in density measurements was achieved between low tube voltage protocol (mean attenuation value of thoracic aorta, 304 HU; abdominal, 343 HU; renal arteries, 331 HU) and control group (mean attenuation value of thoracic aorta, 320 HU; abdominal, 339; renal arteries, 303 HU). Radiation dose exposure in low tube voltage protocol was significantly different between thoracic and abdominal low tube voltage studies (490 and 324 DLP, respectively) and the control group (thoracic DLP, 1032; abdomen, DLP 1078).

Conclusion:

Low-tube-voltage protocol may provide a diagnostic performance comparable with that of the standard protocol, decreasing radiation dose exposure and contrast material volume amount.

Advances in knowledge:

Low-tube-voltage-setting protocol combined with ultra-low contrast agent volume (30 ml), by using new multidetector-row CT scanners, represents a feasible diagnostic tool to significantly reduce the radiation dose delivered to patients and to preserve renal function, while also maintaining adequate diagnostic quality images in assessment of aorta.Since the introduction of multidetector CT (MDCT), CT angiography (CTA) has become a standard imaging tool for the evaluation of diseases affecting the aorta and its major branches.¹ CTA has been advocated for pre-operative evaluation of thoracic and abdominal aortic aneurysms and their relationship with the main branches. Moreover, it is crucial to detect other vascular morbidities, such as dissections and arterial occlusive diseases.² CTA allows the proper visualization of main vascular structures and has several advantages: minimal invasiveness, with a lower complication rate than that of angiography; generation of high spatial resolution images of both the arterial wall and the lumen; availability of multiplanar reconstructions (MPR) and three-dimensional (3D) reconstructions; and short examination times, allowing extended scan ranges.^1,3The extended use of MDCT in the clinical practice, however, may result in an increase of both the frequency of CTA studies and patient''s radiation exposure compared with single-slice CT.⁴ Therefore, CT protocols should be properly designed and carefully applied in order to obtain the highest amount of information by using the lowest radiation dose achievable,^5–10 since the theoretical risk of radiation-induced cancer from CT examinations has been reported as not negligible.¹ As the radiation exposure is linearly dependent on the tube current, a helpful technique for reducing radiation dose involves the modulation of tube current itself, according to real-time local attenuation (i.e. Siemens Medical Solution, Forchheim, Germany and Philips Medical Systems, Best, Netherlands)^5,11 or predictive calculation or sinusoidal interpolation between anteroposterior and lateral views, depending on the different manufacturers.Moreover, the reduction of the X-ray tube voltage, keeping a constant current, can theoretically reduce the radiation exposure exponentially. However, it has to be considered that a lower radiation dose is associated with higher image mottle, and may therefore degrade image quality.⁴The use of large amounts of contrast media (CM) is another concern for CTA, because patients with aortic aneurysms generally tend to be aged and suffer from other comorbidities, such as atherosclerotic renal vascular disease and diabetes. Some studies showed that contrast-induced impairment of renal function directly depends on the amount of CM.^2,12–15Lowering the tube voltage represents the most widely reported technique for reducing the radiation burden in body CTA.¹⁶ This approach allows a significant radiation dose reduction because the dose changes with the square of the tube voltage.¹⁷ Moreover, higher attenuation levels for iodine-based CM are achieved at lower X-ray tube voltages owing to greater photoelectric effect and decreased Compton scattering.¹⁸ The closer the tube voltage approaches the K-edge of iodine (33.2 keV), the greater the inherent attenuation of the iodinated CM is.¹⁹ Hence, a lower CM volume can be injected while obtaining the same vessel attenuation. If current values are not increased correspondingly, the low tube voltage scanning can lead to an increased image noise,¹⁸ but this does not necessarily result in reduced subjective image quality. The increased attenuation of the iodine-containing arterial vessels and the high attenuation differences between the arterial system and poorly enhanced surrounding tissues can partially offset the higher image noise.^16,19The aim of our study was to assess, by using a 256 MDCT scanner, the feasibility of reducing both the radiation dose exposure and the CM volume, in the assessment of thoracic or abdominal aorta and their major branches.     

A planning target volume margin formula for hypofractionated intracranial stereotactic radiotherapy under cone beam CT image guidance with a six-degrees-of-freedom robotic couch and a mouthpiece-assisted mask system: a preliminary study

Objective:

A planning target volume (PTV) margin formula for hypofractionated intracranial stereotactic radiotherapy (SRT) has been proposed under cone beam CT (CBCT) image guidance with a six-degrees-of-freedom (6-DOF) robotic couch.

Methods:

CBCT-based registration using a 6-DOF couch reportedly led to negligibly small systematic positioning errors, suggesting that each in-treatment positioning error during the treatment courses for the patients employing this combination was predominantly caused by a random gaussian process. Under this assumption, an anisotropic PTV margin for each axis was formulated based on a gaussian distribution model. 19 patients with intracranial lesions who underwent additional post-treatment CBCT were consecutively selected, to whom stereotactic hypofractionated radiotherapy was delivered by a linear accelerator equipped with a CBCT imager, a 6-DOF couch and a mouthpiece-assisted mask system. Time-averaged patient-positioning errors during treatment were estimated by comparing the post-treatment CBCT with the reference planning CT images.

Results:

It was suggested that each histogram of the in-treatment positioning error in each axis would approach each single gaussian distribution with a mean of zero. The calculated PTV margins in the x, y and z directions were 0.97, 1.30 and 0.88 mm, respectively.

Conclusion:

The empirical isotropic PTV margin of 2 mm used in our facility for intracranial SRT was consistent with the margin calculated by the proposed gaussian model.

Advances in knowledge:

We have proposed a PTV margin formula for hypofractionated intracranial SRT under CBCT image guidance with a 6-DOF robotic couch.Frameless radiotherapy for treating intracranial lesions has been widely adopted under the guidance of on-board cone beam CT (CBCT) and a mask system with a six-degrees-of-freedom (6-DOF) robotic couch^1–3 or a semi-robotic couch including manual angle adjustments.⁴ Reported maximum registration errors along any Cartesian co-ordinate axis were 0.5 mm for a phantom;¹ and 1.0 or 3.2 mm (mask dependent),² 2.0 ³ and 1.2 mm⁴ for patients. The mean ± standard deviation (SD) along any Cartesian co-ordinate axis was 0.07 ± 0.17 mm for a phantom based on 12 plans and 5 repeated CBCT acquisitions,¹ 0.2 ± 0.4 mm for 10 patients with 6 fractions³ and 0.4 ± 0.3 mm for a phantom and 0.5 ± 0.3 mm for patients including manual couch angle adjustments.⁴ Meyer et al¹ stated that there was no systematic error because they observed a small mean error for their phantom study.Margins between clinical target volumes (CTVs) and planning target volumes (PTVs) are often calculated using a formula proposed by van Herk et al.^5,6 This formula employed two independent statistical models including a patient-to-patient variation model that gives a mean preparation error in all fractions for each patient, and a random error model during treatment delivery owing to random tumour movement. A patient population coverage probability of 90% in a facility was calculated by the patient-to-patient variation model, and the random error model was used to add further margins by increasing penumbra widths. Our intracranial stereotactic radiotherapy (SRT) utilizes an Elekta Synergy® (Elekta AB, Stockholm, Sweden) linear accelerator (linac) equipped with a CBCT imager, XVI and a 6-DOF robotic couch, HexaPOD™ (Elekta AB), which are identical to the system that Meyer et al¹ described. Consequently, our study can be based on the small mean preparation error reported by Meyer et al, and the above margin model may not be applicable. In addition, the previous margin model assumed that the tumour was spherical, and the margin was defined in the radial direction of the spherical co-ordinate system. For example, Guckenberger et al² calculated the PTV margin in the radial direction using registration results for 47 patients with various treatment sites and fixation means, leading to a PTV margin of 1.7 mm that achieved 90% population coverage. Meanwhile, a more accurate margin formula in the Cartesian co-ordinate system that complies with patient couch movements was proposed, in which the margins were anisotropically defined along the x, y and z directions.⁷The purpose of this study was to propose a PTV margin formula as per the Cartesian co-ordinate system for hypofractionated intracranial SRT under CBCT image guidance with a 6-DOF robotic couch.     

Mesenteric panniculitis: prevalence,clinicoradiological presentation and 5-year follow-up

Objective:

To determine prevalence, clinicoradiological characteristics and outcome of patients with mesenteric panniculitis (MP) in a large hospital-based population.

Methods:

Consecutive abdominal CT examinations of 3820 patients were evaluated for MP. Clinical characteristics, therapy and outcome of patients with MP were evaluated during a 5-year follow-up period. A matched pair analysis was performed to further investigate the relation between MP and malignancy.

Results:

94 (2.5%) patients with MP were identified (mean age, 66.6 ± 11.2 years, 70.2% male). MP coexisted with malignancy (especially prostatic carcinoma) in 48.9% of patients, and this was slightly but significantly higher than in age- and sex-matched control patients (n = 188, 46.3%). In 48 patients, MP was presumed to be idiopathic. The most frequent presenting symptom was pain (54.3%). Laboratory findings revealed increased acute-phase reactants in half of the patients with MP. CT findings included increased density of mesenterial fat (mean, −56.8 ± 10.8 HU), fat ring sign, tumoural pseudocapsule and small soft-tissue nodules. Patients with MP (14.6%) developed significantly more malignancies during a 5-year follow-up than did the control group (6.9%). One patient was treated with prednisone without satisfactory response.

Conclusion:

The prevalence of MP in this study was 2.5%. In most patients, radiologic features included increased mesenteric fat density, fat ring sign and small soft-tissue nodules. MP was associated with a significant higher prevalence of coexisting malignancies and a higher prevalence of future cancer development.

Advances in knowledge:

A more accurate prevalence of MP on CT is demonstrated. An underlying malignancy may play a role.Mesenteric panniculitis (MP) is a rare, idiopathic disorder characterized by chronic inflammation of the mesenteric fat. Numerous terms have been reported in literature depending on the pre-dominant presentation, including mesenteric lipodystrophy, sclerosing mesenteritis, mesenteric Weber–Christian disease and retractile mesenteritis or mesenteric fibrosis.^1–8 It is now considered that these different diagnostics entities represent a spectrum of a single disease characterized by non-specific inflammation of the mesentery fat that may ultimately lead to fibrosis and retraction.^1,9,10 The aetiology of MP remains unknown; it may occur independently or in association with other disorders. Various causes have been suggested, including autoimmune disorders, infection, trauma (including recent surgery) and ischaemia of the mesentery.^11,12 It has a poorly understood association with underlying malignancy with conflicting results in literature, which suggests that it may be a paraneoplastic condition at least in some patients.^13–16Owing to the increased use of abdominal diagnostic imaging and the identification of specific signs on CT, MP is being recognized with increasing frequency at CT imaging. To date, mainly case reports and a few larger studies on MP have been published with conflicting results. Reported prevalence rates range from 0.16% to 7.80%.^13–17 Most studies reported this condition in patients in middle and late adulthood with a slight male predominance. Patients may be entirely asymptomatic or present with non-specific mainly gastrointestinal manifestations, including abdominal pain, constipation or diarrhoea, an asymptomatic abdominal mass, weight loss, fever or chylous ascites.^18–21 Depending on the underlying disease, the natural course of MP is often benign and self-limiting, although few data are available on the clinical outcome and response to therapy of patients with MP.The aim of this study was to gain more insight into the prevalence and natural course of MP using strict criteria. We assessed prevalence, clinicoradiological characteristics and outcome of MP during a 5-year follow-up period in a large hospital-based population with specific focus on the relation between MP and malignancy.     

Evaluation of a commercial orthopaedic metal artefact reduction tool in radiation therapy of patients with head and neck cancer

Objective:

To assess the image quality and dosimetric effects of the Philips orthopaedic metal artefact reduction (OMAR) (Philips Healthcare System, Cleveland, OH) function for reducing metal artefacts on CT images of head and neck (H&N) patients.

Methods:

11 patients and a custom-built phantom with metal bead inserts (alumina, titanium, zirconia and chrome) were scanned. The image was reconstructed in two ways: with and without OMAR (OMAR and non-OMAR image). The mean and standard deviation values of CT Hounsfield unit (HU) for selected regions of interest of each case were investigated for both images. Volumetric modulated arc therapy plans were generated for all cases. Gamma analysis of each dose distribution pair in the patient (1%/1 mm criteria) and phantom (2%/2 mm and 3%/3 mm criteria) images was performed. The film measurements in phantom for two metal beads were conducted for evaluating the calculated dose on both OMAR and non-OMAR images.

Results:

In the OMAR images, noise values were generally reduced, and the mean HU became closer to the reference value (measured from patients without metal implants) in both patient and phantom cases. Although dosimetric difference was insignificant for the eight closed-mouth patients (γ = 99.4 ± 0.5%), there was a large discrepancy in dosimetric calculation between OMAR and non-OMAR images for the three opened-mouth patients (γ = 91.1%, 94.8% and 96.6%). Moreover, the calculated dose on the OMAR image is closer to the real delivered dose on a radiochromic film than was the dose from the non-OMAR image.

Conclusion:

The OMAR algorithm increases the accuracy of CT HU and reduces the noise such that the entire radiation treatment planning process can be improved, especially for contouring and segmentation.

Advances in knowledge:

OMAR reconstruction is appropriate for the radiotherapy planning process of H&N patients, particularly of patients who use a bite block.Over the duration of several surgeries and treatments, metallic objects such as orthopaedic implants, surgical staples and clips, radioisotope seeds or dental implants may be inserted into the patient''s body. Owing to the high Z of these materials, metal streak artefacts in the CT image can be induced through the combination of beam hardening, scatter, photon starvation, partial volume effects and aliasing.^1–5 These artefacts cause systematic discrepancies between the true attenuation coefficients of the objects and the CT Hounsfield units (HUs) in the reconstructed image.¹ The discrepancies not only degrade diagnostic image quality but also compromise parts of the radiation treatment planning process such as structure delineation, treatment geometry definition and the extraction of the electron density distribution used for dose calculation.^6–8Since the research with regards to the metal artefact reduction (MAR) algorithm was first introduced in 1981,⁹ several studies have proposed improved methods for MAR, such as the interpolation method,¹⁰ iterative method^11,12 and filtering method.^5,13–22 Recently, the orthopaedic metal artefact reduction function (OMAR; Philips Healthcare System, Cleveland, OH), a commercial MAR module, has become clinically available. The principal method of the Philips OMAR function is an iterative projection modification. The OMAR algorithm divides the original image into a metal-only image and a tissue-classified image, then projection and filtering procedures are performed iteratively so that a corrected image is acquired.²³ Although OMAR has begun to find implementation in radiation oncology clinics, few published studies have evaluated its performance for treatment planning. Li et al²⁴ reported that the use of OMAR can improve the image quality of CT imaging of patients with orthopaedic implants and also that the confidence of radiation oncologists in delineating the target volume could be boosted. Hilgers et al²⁵ reported that the CT numbers acquired by the OMAR reconstruction were more accurate than that of the non-OMAR reconstruction. However, for both studies, the dosimetric differences from CT number correction were not of clinical relevance. Huang et al²⁶ studied several commercial MAR modules including the OMAR function by evaluating several phantoms containing metal implants (hip prostheses, dental fillings and spinal fixation rods). However, this study was limited to the evaluation of the image quality.In the head and neck (H&N) region, metal streak artefacts due to dental implants are common in CT images. Often, during treatment of H&N cancer, a bite block is used to immobilize the oral cavity and make the tongue lie flat.^27,28 This bite block forces the mouth of the patient open, and the CT HU into the oral cavity should be near that of air. For dental implant patients, however, the metal streak artefacts fill the oral cavity with inappropriate HU values and make the mouth of the patient appear sealed in the CT image. For radiation therapy of H&N cancer, it is important to get accurate CT images for target delineation and dose calculation because of the concave-shaped target volumes, the complex anatomy and the relative abundance of sensitive normal tissues close to the target.^29,30 This study evaluated the effectiveness of the OMAR function in correcting for the metal artefacts induced by dental implants in closed- and opened-mouth H&N patients. Moreover, the dosimetric effect was investigated by type of dental implant using a in-house custom-built phantom.     

Non-osseous incidental findings in low-dose whole-body CT in patients with multiple myeloma

Objective:

The purpose of this study was to identify the frequency and grading of non-osseous incidental findings (NOIF) in non-contrast whole-body low-dose CT (LDCT) in patients with multiple myeloma.

Methods:

In the time period from 2010 to 2013, 93 patients with multiple myeloma were staged by non-contrast whole-body LDCT at our radiological department. LDCT images were analysed retrospectively for NOIF, which also included unsuspected extramedullary manifestation of multiple myeloma. All NOIF were classified as major or clinically significant, moderate or possibly clinically significant and minor or not clinically significant. Medical records were analysed regarding further investigation and follow-up of the identified NOIF.

Results:

In the 93 patients, 295 NOIF were identified (on average, 3.2 NOIF per patient). Most of the NOIF (52.4%) were not clinically significant, 25.8% of the NOIF were possibly clinically significant and 21.8% of the NOIF were clinically significant. Clinically significant NOIF were investigated further by CT after intravenous administration of contrast medium and/or by ultrasound or MRI. In 34 of these cases, extramedullary relapse of myeloma, occult carcinoma or infectious/septic incidental findings were diagnosed (11.5% of all NOIF). In the remaining 10.3% of the NOIF classified as clinically significant, various benign lesions were diagnosed.

Conclusion:

LDCT detected various non-osseous lesions in patients with multiple myeloma. 36.6% of the patients had clinically significant NOIF. Therefore, LDCT examinations in patients with multiple myeloma should be evaluated carefully for the presence of NOIF.

Advances in knowledge:

LDCT identified several NOIF. A total of 36.6% of patients with multiple myeloma had clinically significant NOIF. Radiologists should analyse LDCT examinations in patients with multiple myeloma not only for bone lesions, but also for lesions in other organs.CT is used for screening or staging in several malignancies.^1–8 As reported previously, the staging CT examination also provides additional information regarding the general health status of the patient or so-called incidental findings (IF).^1,3,6,7 Several IF on CT examinations were described in the literature.^1–6 According to previous reports, IF can be classified into five different categories: Group “0”, limited examination, that is, evaluation of IF are severely limited; Group “1”, normal findings or anatomic variant; Group “2”, clinically unimportant findings, such as liver or kidney cysts; Group “3”, likely unimportant findings; and Group “4”, potentially important findings, such as solid renal masses or lymphadenopathy.⁵ In another publication, a three-part classification of IF according to their clinical importance was proposed, namely major, moderate and minor IF.¹Most of the IF are clinically non-significant, such as colonic diverticula or simple cysts.^1–7 However, serious IF, such as aortic aneurysm or dissection, thrombosis, pulmonary embolism and second primary tumours, can also occur,^1,3,6,7 and some of them may be not visible on low-dose CT (LDCT).Most reports regarding IF are based on contrast-enhanced CT.^1,7,9–11 There are only a few reports regarding IF in LDCT.¹² They described IF in screening programmes for lung cancer and based the findings on thoracic LDCT only.¹² In addition, non-contrast LDCT has been established for staging of bone lesions in multiple myeloma.^13–16 However, radiologists should analyse LDCT examinations not only for bone lesions but also for lesions in other organs, which may include extramedullary manifestation of multiple myeloma as well as unrelated IF.Although IF in multiple myeloma have also been described previously,¹⁴ to the best of our knowledge, there exists no analysis focused on frequency and distribution of non-osseous IF (NOIF) on whole-body LDCT. Therefore, the purpose of this study was to identify the frequency and grading of NOIF in non-contrast whole-body LDCT in patients with multiple myeloma.