Early assessment of chronic kidney dysfunction using contrast-enhanced ultrasound: a pilot study

Objective:

We performed a prospective study to evaluate the value of contrast-enhanced (CE) ultrasound in quantitative evaluation of renal cortex perfusion in patients with chronic kidney dysfunction (CKD Stage I–II).

Methods:

The present study was approved by the institutional ethics committee. The study focused on 41 consecutive patients (males, 32; females, 9; mean age, 55.0 ± 5.0 years) with clinical suspicion of CKD (Stages I–II). For both kidneys, CE ultrasound was performed after intravenous bolus injection of 1.0 ml SonoVue® (Bracco Imaging S.p.A., Milan, Italy). Time–intensity curves (TICs) and quantitative indexes were created with Qlab software (Philips, Bothell, WA). 45 healthy volunteers were included as control group. All statistical analyses were performed with SPSS® v. 15.0 software package (SPSS, Chicago, IL). A difference was considered statistically significant with p < 0.05.

Results:

Patients with CKD (Stages I–II) had no obvious change in the shape of TICs. Among all quantitative indexes, the changes of area under the curve (AUC), derived peak intensity (DPI) and slope rate of elevation curve (A) were statistically significant (p < 0.05). DPI <12 dB, A >2 and AUC >1300 dB s had high utility in the evaluation of CKD, with 81%, 73% and 78% specificities and 76%, 73% and 77% sensitivities.

Conclusion:

CE ultrasound might be valuable in the early evaluation of CKD. AUC, A and DPI might be valuable quantitative indexes.

Advances in knowledge:

Quantitative CE ultrasound analysis can be used for the standardized and early evaluation of renal dysfunction.Throughout the world, chronic kidney dysfunction (CKD) is a growing health concern because of its increasing prevalence and incidence rate.¹ Since CKD primarily involves perfusion changes in the renal cortex, assessment of tissue perfusion is an important component for the evaluation of CKD.² Early and detailed visualizations of perfusion changes of the renal cortex yield information about organ viability and function, which would be crucial to make diagnosis and to initiate early drug therapy.³Different non-invasive imaging modalities, such as multidetector CT,⁴ positron emission tomography,⁵ MRI⁶ and single-photon emission CT with ^99mTc-diethylenetriamine pentaacetic acid⁷ are used in the quantifications of tissue perfusions. However, high costs, reduced availability, long examination periods, patients'' exposure to radiation or nuclear tracers limited clinical applications of these techniques.^4–7 Greyscale renal ultrasound combined with colour Doppler flow imaging (CDFI) had become the main non-invasive imaging methods for evaluating the renal anatomy and blood flow.⁸ However, CDFI parameters such as the resistance index (RI) and peak systolic velocity (PSV) provided only indirect macrovasculature parameters, which could not directly assess renal cortex perfusion and were of limited diagnostic use in the CKD.⁹ To date, there was no reliable, accurate and convenient method to determine renal blood perfusion in vivo, thereby leading to difficulty in early and accurate diagnosis of CKD.In recent years, low mechanical index (MI) real-time contrast-enhanced (CE) ultrasound has been proposed as an alternative imaging technique in this area.¹⁰ Because microbubbles are blood-pool agents, when injected intravenously, they remain entirely intravascular, mix uniformly with blood in the circulation and possess the same intravascular rheology as red blood cells.¹¹ The advantages of CE ultrasound include the absence of ionizing radiation or nephrotoxicity, and the widespread availability. When CE ultrasound is performed immediately after a non-conclusive ultrasound study, only a short time was needed to arrive at a final diagnosis.¹² CE ultrasound has been recently used as a new imaging technique for quantifying tissue perfusion changes in the liver,¹³ heart¹⁴ and kidney.¹⁵ The large blood supply of the kidney was a good base for contrast studies, as >90% of kidney blood flow supplied the renal cortex by the renal arterioles and capillaries.¹⁶ Since CE ultrasound microbubbles remain strictly inside the vessels, they can be viewed as blood-pool markers enabling functional imaging of the kidney.¹⁷ The increase in echo signal intensity after microbubble injection may be quantified by dedicated software packages to produce time–intensity curves (TICs). Enhancement-based representations had been used to assess unilateral kidney dysfunction such as in renal artery stenosis by a simple analysis of the tracer concentration curve.¹⁸ These features made low MI CE ultrasound a promising technique in evaluation of renal cortex perfusion.The purpose of this initial study was to evaluate the feasibility of CE ultrasound to assess renal cortex tissue perfusion in the early stages of CKD (Stages I–II) by means of TICs. The diagnostic efficacy gained by quantitative CE ultrasound was compared with that of renal arterial PSV and RI measured by CDFI.     

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.     

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.     

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.     

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”.     

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.     

Medial temporal lobe atrophy in Alzheimer's disease/mild cognitive impairment with depression

Objective:

Depression is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Patients with depression have an earlier onset and rapid progression of cognitive decline. Medial temporal lobe atrophy (MTA) is common in AD and MCI, and some degree of atrophy is found in almost all patients. In the present study, an attempt was made to know if MTA is more common in patients with AD/MCI with depression than those without it.

Methods:

Patients reporting to the outpatient department of a neurology centre of a tertiary care hospital were recruited for the present study. After initial general physical and neurological examination, they were evaluated using National Institute of Neurological and Communicative Disorders and Stroke and Related Disorders Association criteria for diagnosis of AD. Clinical Dementia rating scale was used for the diagnosis of MCI. Cornell scale for depression in dementia (CSDD) was used.

Results:

We found 20 cases with depression as per CSDD out of a sample of 37 patients (male:female = 30:7). There were 26 patients with AD and 11 with MCI. The mean age of all patients was 72.33 ± 6.45 years. The mean mini mental status examination score was 19.00 ± 6.73. The mean time since diagnosis was 4.19 ± 3.26 years. The mean Scheltens visual rating scale score for right MTA was 2.08 ± 0.95 and was 2.05 ± 0.94 for the left. Both scores did not differ statistically when analyzed using paired t-test (p > 0.05). However, difference in those with depression (2.36 ± 0.95) from those without depression (1.60 ± 0.74) was significant (p < 0.05).

Conclusion:

MTA scores were higher in those with AD/MCI with depression than those without it.Depression¹ is common in patients with Alzheimer''s disease (AD) and mild cognitive impairment (MCI). Relationship between depression and cognitive decline is a complex one, and depression is both an aetiological risk factor² and comorbidity for dementia.³ Incidence and prevalence of depressive symptoms in MCI range from 15% in population-based studies to 44% in hospital-based studies.⁴ Likewise, up to two-thirds of patients with AD have been reported to have depression.⁵ Because in many studies, depression has been seen to be an early manifestation of AD, it has been suggested that it may represent a continuum⁴ from depression to MCI to AD (late-life depression → MCI → AD). Two recent meta-analyses have found that a history of depression approximately doubles an individual''s risk for subsequent dementia in general and AD in particular.⁶ Depression is known to be neurotoxic to medial temporal lobe structures and can contribute to their atrophy.^7–9 Atrophy is more so, when depression is severe or recurrent⁷ and medial temporal lobe atrophy (MTA) has a temporal association with depression.⁹ Continued treatment of depression has been shown to protect the hippocampus from the ill effects of depression.¹⁰ Although volumetric method could be a preferred mode of measuring the hippocampal volume in AD, qualitative rating of MTA is a good alternative.¹¹ Visual rating of the hippocampal volume^12–14 can be carried out using Scheltens et al¹⁵ rating scale that is based on the width of the choroid fissure, the width of the temporal horn and the height of hippocampal formation and is a quantitative scale.     

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.     

Stage T3a renal cell carcinoma: staging accuracy of CT for sinus fat,perinephric fat or renal vein invasion

Objective:

To study the accuracy of CT for staging T3a (TNM 2009) renal cell carcinoma (RCC).

Methods:

Unenhanced and nephrographic phase CT studies of 117 patients (male:female = 82:35; age range, 21–86 years) with T1–T3a RCC were independently reviewed by 2 readers. The presence of sinus or perinephric fat, or renal vein invasion and tumour characteristics were noted.

Results:

Median (range) tumour size was 5.5 (0.9–19.0) cm; and 46 (39%), 16 (14%) and 55 (47%) tumours were pT1, pT2 and pT3a RCC, respectively. The sensitivity/specificity for sinus fat, perinephric fat and renal vein invasion were 71/79%, 83/76% and 59/93% (Reader 1) and 88/71%, 68/72% and 69/91% (Reader 2) with κ = 0.41, 0.43 and 0.61, respectively. Sinus fat invasion was seen in 47/55 (85%) cases with T3a RCC vs 16/55 (29%) and 33/55 (60%) for perinephric fat and renal vein invasion. Tumour necrosis, irregularity of tumour edge and direct tumour contact with perirenal fascia or sinus fat increased the odds of local invasion [odds ratio (OR), 2.5–3.7; p < 0.05; κ = 0.42–0.61]. Stage T3a tumours were centrally located (OR, 3.9; p = 0.0009).

Conclusion:

Stage T3a RCC was identified with a sensitivity of 59–88% and specificity of 71–93% (κ = 0.41–0.61). Sinus fat invasion was the most common invasive feature.

Advances in knowledge:

Centrally situated renal tumours with an irregular tumour edge, inseparable from sinus structures or the perirenal fascia and CT features of tumour necrosis should alert the reader to the possibility of Stage T3a RCC (OR, 2.5–3.9).Current guidelines¹ recommend nephron-sparing procedures (either partial nephrectomy or ablation) for Stage T1a (<4 cm) renal cell carcinomas (RCCs), but the indications for nephron-sparing procedures are widening.² Successful surgical series have been reported with Stage T1b (<4–7 cm) tumours and even Stage T2 RCCs.³ Central location is not necessarily a barrier to good clinical outcome after partial nephrectomy,³ but nephron-sparing procedures are contraindicated for stage ≥T3a renal cancers.¹ Thus, prior accurate recognition of T3a stage is important, especially with central renal masses, as any pre-operative suspicion of local invasion should contraindicate nephron-sparing surgery or ablation.In the most recent TNM iteration, Stage T1 and T2 tumours are defined by tumour diameter (T1a, ≤4 cm; T1b, 4–7 cm; T2a, 7–10 cm; and T2b, ≥10 cm) and the absence of any local invasion. Stage T3a RCC was redefined to include invasion of either renal sinus or perinephric fat.⁴ Renal vein invasion [main renal vein and/or segmental (muscle-containing) branch invasion], without caval involvement, was downgraded from Stage T3b to Stage T3a, whilst adrenal invasion was upgraded from Stage T3a to Stage T4. Size is not a governing factor with ≥T3a tumours, and some renal masses <7 cm in diameter will be locally advanced. Nearly half of all pT3a RCCs (n = 309/623) in one study were <7 cm in diameter.⁵ Other studies have confirmed the poor prognostic significance of sinus fat or venous invasion in masses <7 cm, with a 4–6 times increased risk of cancer-related death.^6,7 Centrally located masses are more likely to demonstrate local invasion with positive surgical resection margins after partial nephrectomy,^8,9 and unrecognized sinus invasion may explain the recurrence of cancer, and subsequent death from metastatic disease, in some cases of presumed T1 RCCs.⁸However, in previous studies, CT staging has been variably accurate^10–18 for RCCs, and staging inaccuracies, usually understaging, are said to be most common with Stage T3a disease.^12,17 For venous invasion, the specificity and sensitivity have ranged between 58–97% and 32–96%,^10,14–16 and for perinephric infiltration, the figures have been 32–96% and 85–93%,^14–16 respectively. The CT accuracy for sinus fat invasion has not been previously investigated. The primary aim of this study was to define the accuracy of contrast-enhanced CT for identifying any of the three defining features of Stage T3a RCC, that is, sinus or perinephric fat invasion, or renal vein invasion. Secondary study objectives were to identify any tumour characteristics that increase the odds of T3a disease and may be used as accessory CT signs to alert the reader to an increased likelihood of local invasion by RCC.     

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.     

Percutaneous radiofrequency ablation of spinal osteoid osteoma under CT guidance

Objective:

Osteoid osteoma (OO) accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. Spinal involvement appears in 10–25% of all cases. The purpose of this study was to evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation in the treatment of spinal OOs and report our experience.

Methods:

13 patients suffering from spinal OO and treated at the authors'' institution using CT-guided RF ablation were retrospectively evaluated. The RF probe was introduced through a 11-G Jamshidi® needle, and the lesion was heated at 90 ^°C for 6 min.

Results:

All procedures were considered technically successful as the correct positioning of the probe was proven by CT. 11 of the 13 patients reported pain relief after RF ablation. In two cases, RF ablation was repeated 1 month after the first procedure. Pain relief was achieved in both cases after the second procedure. No recurrence was reported throughout the follow-up. No complications like skin burn, soft-tissue haematoma, infection, vessel damage or neurological deficit were reported.

Conclusion:

This study demonstrates that CT-guided percutaneous RF ablation is a safe and effective method for the treatment of spinal OOs.

Advances in knowledge:

The data of this study support the efficacy and safety of the recently applied CT-guided percutaneous RF ablation technique for the treatment of spinal OOs.Osteoid osteoma (OO) represents a benign bone tumour first described by Jaffe¹ in 1935. The lesion accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. It is characterized by a nidus, consisting of osteoid, osteoblasts and fibrovascular stroma, surrounded by sclerotic bone usually measuring <1.5 cm in diameter. OOs are characteristically seen in children and young adults with a predilection for long bones, particularly in lower extremities.² Spinal involvement usually affecting the posterior elements appears in 10–25% of all cases.^3,4 The typical symptom is localized pain typically worsening at night, ameliorated by the administration of salicylates (acetylsalicylic acid) or non-steroidal anti-inflammatory drugs (NSAIDs). In spinal cases of OO, radiation of pain distally to the lesion site might simulate radiculopathy similar to disc herniation especially if the lesion is located close to a nerve root. Painful antalgic scoliosis is frequent in thoracolumbar lesions in children and adolescents.^5,6 Spinal lesions are usually difficult to diagnose, and the reported delay from presentation to final diagnosis and treatment can be as long as 24 months in some cases.^7–9 Neurologic deficit does not generally appear.In the past, conventional surgical excision and more recently minimally invasive surgery techniques were the treatment of choice in cases of spinal OOs when conservative treatment with anti-inflammatory and salicylates fails or is contraindicated.^10–15Rosenthal et al¹⁶ first introduced percutaneous radiofrequency (RF) ablation for the treatment of OOs. The effectiveness of RF ablation of OOs localized in the extremities and pelvis has been proven by many studies.^16–19Percutaneous RF ablation for the treatment of spinal OOs is not widely used, probably owing to the potential danger to the adjacent neural and vascular elements. In recent years, however, some clinical studies reported good results in the management of spinal OOs using CT-guided RF ablation.^8,20–23The purpose of this study was to evaluate the safety and efficacy of CT-guided RF ablation in the treatment of spinal OOs and report our experience.     

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.     

Application of contrast-enhanced ultrasonography in the diagnosis of skeletal muscle crush injury in rabbits

Objective:

To explore the diagnostic value of quantitative contrast-enhanced (CE) ultrasonography for crush injury in the hind limb muscles of rabbits.

Methods:

A total of 120 New Zealand white rabbits were randomized to receive compression on the left hind limb for either 2 h (n = 56) or 4 h (n = 56) to induce muscle crush injury. Another eight animals were not injured and served as normal controls. CE ultrasonography parameters such as peak intensity (PI), ascending slop, descending slop and area under curve (AUC) were measured at 0.5, 2, 6 and 24 h and 3, 7 and 14 days after decompression.

Results:

Compared with the uninjured muscles, reperfusion of the injured muscles showed early and high enhancement in CE ultrasonography images. The time-intensity curve showed a trend of rapid lift and gradual drop. The PI and AUC values differed significantly among the three groups and were positively correlated with serum and tissue biomarkers. Rabbits of the 4-h compression group showed significantly higher PI and AUC values, and serum and tissue parameters than the 2-h compression group at each time points.

Conclusion:

CE ultrasonography can effectively detect muscle crush injury and monitor dynamic changes of the injured muscles in rabbits. PI and AUC are promising diagnostic parameters for this disease.

Advances in knowledge:

CE ultrasonography might play an important role in the pre-hospital and bedside settings for the diagnosis of muscle crush injury.Muscle crush injury usually occurs during earthquakes, collapse of buildings and heavy whip beatings, and often induces crush syndrome if not treated promptly. Crush injury is estimated to account for 3–20% of all injuries during natural disasters, and the lower limbs are the most frequently affected.¹ Limb crush injury and its complications are life threatening and the most frequent cause of disability and death after earthquakes.²The mortality rate in patients with crush syndrome can be as high as 21%, which is the most dangerous complication of all injuries during disasters.³ Crush syndrome can cause acute kidney injury and acute osteofascial compartment syndrome (AOCS), which are the most life-threatening complications. AOCS has a 47% mortality, and unrecognized AOCS can leave a patient with non-viable limbs requiring amputation.⁴ Severe muscle crush injury can also result in multiple organ dysfunction syndrome, acute respiratory distress syndrome, disseminated intravascular coagulation and severe arrhythmia.⁵ Early diagnosis of muscle crush injury and correct assessment of its severity are critical for good prognosis of patients. However, bedside and pre-hospital diagnosis of crush injury still lacks effective methods.Typical muscle crush injury and related AOCS are usually diagnosed with clinical symptoms, but the sensitivity of this method is very low.^6,7 Impaired microcirculation is the initial pathological change of crushed muscles.⁴ A variety of imaging methods have been used to examine reperfusion of the extremities and therefore detect the presence of muscle crush injury, such as CT, MRI and ultrasonography.^8–11 However, the equipment of CT and MRI is large and inconvenient for bedside or pre-hospital settings or in situ care at the trauma scene. On the contrary, ultrasonography devices can be light, portable and convenient for bedside or traumatic scenes. Ultrasonography also has no radiation. Conventional ultrasonography has been used to determine limb muscle crush injury, rhabdomyolysis and AOCS during the 2008 Sichuan earthquake in China.¹² However, the sensitivity of conventional ultrasonography is low for the diagnosis of extremity crush injury, and its detecting ability of microvascular perfusion is also very poor.¹³Gas-filled microbubbles can significantly augment the back scattered signals and do not leak out of the blood vessel and therefore are used as a contrast agent for Doppler ultrasonography to trace the bloodstream. Contrast-enhanced (CE) ultrasonography has been successfully used to measure microcirculation of the skeletal muscles, such as measurement of muscle perfusion after exercise, and evaluation of muscle perfusion in inflammatory myopathy or peripheral arterial disease.^14–16 However, application of CE ultrasonography in the assessment of microcirculation perfusion in muscle crush injury has rarely been reported.¹⁷In this study, microcirculation of extremities that underwent crush injury were evaluated using CE ultrasonography to investigate the values of CE ultrasonography in diagnosing limb crush injury.     

Radiographers' professional knowledge regarding parameters and safety issues in plain radiography: a questionnaire survey

Objective:

To review the knowledge of radiographers and examine the possible sociodemographic and situational contributors to this knowledge.

Methods:

A questionnaire survey was devised and distributed to a cohort of 120 radiographers. Each questionnaire contained two sections. In the first section, background data, including sex, age, highest academic level, grade point average (GPA), length of time from graduation, work experience as a radiographer and the status of previous refresher course(s), were collected. The second section contained 17 multiple-choice questions concerning radiographic imaging parameters and safety issues.

Results:

The response rate was 63.8%. In univariate analytic model, higher academic degree (p < 0.001), higher GPA (r² = 0.11; p = 0.001), academic workplace (p = 0.04) and taking previous refresher course(s) (p = 0.01) were significantly associated with higher knowledge score. In multivariate analytic model, however, higher academic degree (B = 1.62; p = 0.01), higher GPA (B = 0.50; p = 0.01) and taking previous refresher course(s) (B = −1.26; p = 0.03) were independently associated with higher level of knowledge. Age, sex, length of time from graduation and work experience were not associated with the respondents'' knowledge score.

Conclusion:

Academic background is a robust indicator of a radiographer''s professional knowledge. Refresher courses and regular knowledge assessments are highly recommended.

Advances in knowledge:

This is the first study in the literature that examines professional knowledge of radiographers in terms of technical and safety issues in plain radiography. Academic degree, GPA and refresher courses are independent predictors of this knowledge. Regular radiographer professional knowledge checks may be recommended.The Joint Commission on Accreditation of Healthcare Organizations mandates “processes that are designed to ensure that the competency of all staff members is assessed, maintained, demonstrated and improved on an ongoing basis.” Tests with practical questions that reflect the knowledge required to perform daily examinations have been proposed as effective tools to attain this purpose. The results enable us to take on existing blemishes and improve the competency.¹Medical imaging, as a field with growing complexity and increasing impact on diagnosis, plans of management and patient health status,² is a good example of raised requirements for competency.^3–8Knowledge assessment may be useful for detecting possible weaknesses in an organization and spotlighting existing educational flaws and shortcomings.⁹ According to some reports, knowledge assessment takes priority over checking competency,^7,10 particularly in professions that are completely mediated by technology.¹¹In addition, although clinical education is the mainstay for developing skills, it has been shown that the combination of practical and theoretical education would lead to a significantly better outcome in the field of teaching. This integrated approach of using both knowledge and practice in education enables the trainee to work more competently and be prepared to take responsibility in his/her future career.¹²Although radiography using film for imaging the internal organs of the body has been introduced for over a century,¹³ it is still among the most widespread and useful imaging modalities all over the world. Radiographers are generally in charge of radiological equipment, imaging examination and frequently nursing care.^7,14,15Incompetent radiographers could render radiographic examinations suboptimal. A poor radiographic technique, in turn, may lead to unnecessary exposures to X-radiation, poor image quality, repeated views and examinations, patient discomfort or further injury because of poor positioning and the possibility of a missed diagnosis or misdiagnosis.¹⁶Furthermore, a rapid shift from conventional to fully digitized radiology departments, along with rapidly evolving changes in healthcare administration¹⁷ entails knowledgeable, up-to-date radiographers who utilize the technology.¹⁸Except for very limited number of studies that have described radiographers'' self-reported competency^7,16 and the level of awareness pertaining to the protection against radiation,^19,20 to the best of our knowledge, there is no study in the literature regarding radiographers'' level of knowledge with a dedicated focus on technical parameters and safety in plain radiography.This study sets out to examine knowledge amongst a cohort of radiographers and to investigate possible association of some sociodemographic and situational factors with the level of this knowledge.     

Model-based vs hybrid iterative reconstruction technique in ultralow-dose submillisievert CT colonography

Objective:

To compare image quality of different reconstruction techniques in submillisievert ultralow-dose CT colonography (CTC) and to correlate colonic findings with subsequent optical colonoscopy.

Methods:

58 patients underwent ultralow-dose CTC. The images were reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR) or model-based iterative reconstruction (MBIR) techniques. In each segment, endoluminal noise (expressed as standard deviation of endoluminal density) was measured and image quality was rated on a five-point Likert scale by two independent readers. Colonic lesions were evaluated in consensus and correlated with subsequent optical colonoscopy where possible.

Results:

The estimated radiation dose was 0.41 ± 0.05 mSv for the supine and 0.42 ± 0.04 mSv for the prone acquisitions. In the endoluminal view, the image quality was rated better in HIR, whereas better scores were obtained in MBIR in the cross-sectional view, where the endoluminal noise was the lowest (p < 0.0001). Five (26%) polyps were not identified using both computer-aided detection and endoluminal inspection in FBP images vs only one (5%) in MBIR and none in HIR images.

Conclusion:

This study showed that in submillisievert ultralow-dose CTC, the image quality for the endoluminal view is better when HIR is used, whereas MBIR yields superior images for the cross-sectional view. The inferior quality of images reconstructed with FBP may result in decreased detection of colonic lesions.

Advances in knowledge:

Radiation dose from CTC can be safely reduced <1 mSv for both positions when iterative reconstruction is used. MBIR provides better image quality in the cross-sectional view and HIR in the endoluminal view.CT colonography (CTC) has a comparable sensitivity and specificity to optical colonoscopy (OC) in diagnosing relevant colonic lesions.^1,2 Compared with OC, its major disadvantages are the radiation dose and the inability to biopsy or remove polyps.^3,4 Although the true risk of stochastic effects from a CTC examination in adults is very low, its routine large-scale use must be responsibly weighted against its benefits.⁵ Fortunately, high contrast among colonic wall, intraluminal air and tagged stool, as well as the widely accepted minimal size of a polyp to be reported (which relates to the required spatial resolution), allow reduction of the time–current product to 50–30 mAs in a 120-kV protocol without sacrificing diagnostic acceptability.⁶ For CTC, the estimated benefit–risk ratio of 24–35 : 1 per 7–8 mSv can be increased in direct proportion to the decrease of the radiation dose, provided that the image quality is maintained.⁴ Further reduction of the radiation dose while maintaining diagnostic acceptability requires special considerations regarding acquisition and image-processing techniques.^7–9 In particular, new developments in the field of iterative reconstruction offer further reduction of the radiation dose with preserved image quality.^7,10The objective of this study was to compare image quality of different reconstruction techniques in a submillisievert ultralow-dose CTC in order to assess image quality and recommend the most applicable technique. Furthermore, we evaluated colonic findings and, where possible, correlated the findings with subsequent OC.     

Quantitative pixelwise myocardial perfusion maps from first-pass perfusion MRI

Objective:

To calculate and evaluate absolute quantitative myocardial perfusion maps from rest first-pass perfusion MRI.

Methods:

10 patients after revascularization of myocardial infarction underwent cardiac rest first-pass perfusion MRI. Additionally, perfusion examinations were performed in 12 healthy volunteers. Quantitative myocardial perfusion maps were calculated by using a deconvolution technique, and results were compared were the findings of a sector-based quantification.

Results:

Maps were typically calculated within 3 min per slice. For the volunteers, myocardial blood flow values of the maps were 0.51 ± 0.16 ml g⁻¹ per minute, whereas sector-based evaluation delivered 0.52 ± 0.15 ml g⁻¹ per minute. A t-test revealed no statistical difference between the two sets of values. For the patients, all perfusion defects visually detected in the dynamic perfusion series could be correctly reproduced in the maps.

Conclusion:

Calculation of quantitative perfusion maps from myocardial perfusion MRI examinations is feasible. The absolute quantitative maps provide additional information on the transmurality of perfusion defects compared with the visual evaluation of the perfusion series and offer a convenient way to present perfusion MRI findings.

Advances in knowledge:

Voxelwise analysis of myocardial perfusion helps clinicians to assess the degree of tissue damage, and the resulting maps are a good tool to present findings to patients.MRI is widely used for the evaluation of myocardial perfusion. Advantages of perfusion MRI are a higher spatial resolution compared with positron emission tomography (PET)^1,2 and single photon emission CT³ and the lack of exposure to radiation. Great efforts have been made to use MRI for quantitative evaluation of myocardial perfusion in the past years.^4,5 In clinical routine, however, evaluation of MRI perfusion examinations is performed by the visual analysis of the acquired images depicting areas remaining hypo-intense during the passage of the contrast agent bolus. One main reason for not quantifying myocardial perfusion is the sometimes-excessive user interaction time required for manual segmentation of the acquired images in the quantification process.If myocardial perfusion is quantified, in most studies, the high spatial resolution of the acquired MR images is not maintained. Instead, a sector-based evaluation is performed.^6,7 First attempts have been made to calculate myocardial perfusion maps to evaluate regional myocardial perfusion.^3,8–10 However, until now, these studies were performed in animals^8–10 or perfusion was only evaluated semiquantitatively.³ Recently, our group has published an automatic post-processing tool for quantitative perfusion evaluation.¹¹ That study focused on the automation of post-processing but confined itself on sectors of the myocardium. The next and consequent step is to evolve this technique to work on a pixel-by-pixel basis. Therefore, it was the goal of this study to develop and test a method that calculates pixelwise quantitative perfusion maps from myocardial perfusion MRI examinations. These maps might help the clinician in making a diagnosis by decreasing the number of images to be examined, because a pixelwise quantitative perfusion map demonstrates the information of a whole series of images obtained in a first-pass perfusion examination clearly arranged.     

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.