Chest X-ray in intensive care unit patients: what there is to know about thoracic devices

Critically ill patients admitted to the intensive care unit require continuous monitoring of vital functions as well as mechanical and pharmacological support, provided through different devices. Chest radiographs play a fundamental role in monitoring the conditions of these patients and assessing the intensive-care devices after their insertion; therefore, the radiologist needs to know their normal appearance and their correct position and should be aware of the possible complications that may occur after their placement. This pictorial review illustrates the radiographic appearance of non-cardiological devices commonly used in clinical practice (central venous catheters, tunneled catheters, Swan-Ganz catheters, chest tubes, endotracheal tubes, and nasogastric tubes), their correct position and the most common complications that may occur after their placement.

Critically ill patients in the intensive care unit require continuous monitoring of vital functions and mechanical and pharmacological support, provided through different devices. Inserting intensive-care devices is a common medical practice but complications may occur and a chest X-ray radiography (CXR) should be performed immediately after placement (1). The widespread availability along with low radiation exposure and low costs, give CXR a decisive role in these settings to assess the position of the device, the response to therapy and the occurrence of any complications (2) (Fig. 1). Radiologists should be aware of the normal appearance of these devices and promptly recognize any abnormal findings.Open in a separate windowFigure 1A technically correct bedside chest X-ray performed in the intensive care unit. The exam allows to evaluate the position of inserted chest devices (chest tubes, black asterisks; endotracheal tube, white asterisk; pulmonary artery catheter, black arrowhead; nasogastric tube – proximal portion, white arrowhead) and to detect the presence of bilateral pleural effusions (white arrows) and the occurrence of soft tissue emphysema (black arrow). The patient underwent heart surgery and prosthetic valves, median sternotomy wires and external cardiac monitor wires are also present.This pictorial review illustrates the radiographic appearance of commonly used non-cardiological devices (

Resistive intrarenal index: myth or reality?

In renal diagnosis, the B-mode ultrasound is used to provide an accurate study of the renal morphology, whereas the colour and power Doppler are of strategic importance in providing qualitative and quantitative information about the renal vasculature, which can also be obtained through the assessment of the resistive index (RI). To date, this is one of the most sensitive parameters in the study of kidney diseases and allows us to quantify the changes in renal plasma flow. If a proper Doppler ultrasound examination is carried out and a critical analysis of the values obtained is performed, the RI measurement at the interlobar artery level has been suggested in the differential diagnosis between nephropathies. The aim of this review is to highlight the pathological conditions in which the study of intrarenal RI provides useful information about the pathophysiology of renal diseases in both the native and the transplanted kidneys.Renal ultrasonography has acquired a strategic importance in the early detection of several renal diseases thanks to its non-invasivity, low cost, reliability and high sensitivity. The B-mode ultrasound is a widely used technique for the study of kidney morphology, including renal pelvis, to provide information on parenchymal echogenicity and to detect space-occupying lesions.The characteristic ultrasonographic pattern in chronic kidney disease (small kidneys, reduced parenchymal thickness and detection of cysts) allows a simple and accurate diagnosis of this pathological condition. On the other hand, the diagnostic validity of the B-mode ultrasound in the detection of acute renal disease is still under debate because of the lack of sensitivity and specificity of the commonly used parameters such as the increase of renal size and the reduction of the parenchymal echogenicity.The advantage of using Doppler ultrasound (DUS) lies in its ability in detecting not only renal morphological abnormalities but also functional ones; colour Doppler, power DUS and spectral analysis provide qualitative and quantitative haemodynamic information about the intrarenal and extrarenal vasculature highlighting changes in the renal blood flow.The measure of renal resistive index (RI) or Pourcelot index is one of the most sensitive parameters in the study of disease-derived alterations of renal plasma flow.The aim of this review is to evaluate the significance of the renal RI as a non-invasive marker of renal histological damage in several pathological conditions (Clinical settingRIProposed clinical valueAll nephropathies>0.75Indicator of tubulointerstitial nephropathy1AKI>0.75Useful in discriminating between ATN and pre-renal form²Chronic renal failure>0.80Indicator of irreversible damage>0.70Independent risk factor for worsening function^3–6Renal colic>0.70Signs of complete ureteral obstruction^7,8∆RI > 0.08–0.10Kidney transplantation>0.80In SKT graft, unfavourable prognostic factor⁹>0.80Association with recipient survival¹⁰  >0.75Long-term RF for NODAT¹¹DiabetesType 1—children 7–15 years old>0.64Risk factor for diabetic nephropathy¹²Type 2>0.70Indicator of advanced glomerular lesions and/or arteriosclerotic lesions¹³ >0.73Predictor of DN and its progression¹⁴Renal artery stenosis>0.80Poor renal improvement after PTA¹⁵Cirrhosis>0.78Risk factor for HRS¹²Open in a separate windowΔRI, difference in resistive index; AKI, acute kidney injury; ATN, acute tubular necrosis; DN, diabetic nephropathy; HRS, hepatorenal syndrome; NODAT, new-onset diabetes after transplantation; PTA, percutanous transluminal angioplasty; SKT, single kidney transplantation.     

Post-cholecystectomy syndrome: spectrum of biliary findings at magnetic resonance cholangiopancreatography

Post-cholecystectomy syndrome (PCS) is defined as a complex of heterogeneous symptoms, consisting of upper abdominal pain and dyspepsia, which recur and/or persist after cholecystectomy. Nevertheless, this term is inaccurate, as it encompasses biliary and non-biliary disorders, possibly unrelated to cholecystectomy. Biliary manifestations of PCS may occur early in the post-operative period, usually because of incomplete surgery (retained calculi in the cystic duct remnant or in the common bile duct) or operative complications, such as bile duct injury and/or bile leakage. A later onset is commonly caused by inflammatory scarring strictures involving the sphincter of Oddi or the common bile duct, recurrent calculi or biliary dyskinesia. The traditional imaging approach for PCS has involved ultrasound and/or CT followed by direct cholangiography, whereas manometry of the sphincter of Oddi and biliary scintigraphy have been reserved for cases of biliary dyskinesia. Because of its capability to provide non-invasive high-quality visualisation of the biliary tract, magnetic resonance cholangiopancreatography (MRCP) has been advocated as a reliable imaging tool for assessing patients with suspected PCS and for guiding management decisions. This paper illustrates the rationale for using MRCP, together with the main MRCP biliary findings and diagnostic pitfalls.Post-cholecystectomy syndrome (PCS) consists of a group of abdominal symptoms that recur and/or persist after cholecystectomy [1, 2]. It is defined as early if occurring in the post-operative period and late if it manifests after months or years.Although this term is used widely, it is not completely accurate, as it includes a large number of disorders, both biliary (1, 2]. It has been reported that ∼50% of these patients suffer from organic pancreaticobiliary and/or gastrointestinal disorders, whereas the remaining patients are affected by psychosomatic or extra-intestinal diseases. Moreover, in 5% of patients who undergo laparoscopic cholecystectomy, the reason for chronic abdominal pain remains unknown [1]. Probably because of the uncertainty in nosographic definition, the reported prevalence of PCS ranges from very low [2] to 47% [1]. Symptoms include biliary or non-biliary-like abdominal pain, dyspepsia, vomiting, gastrointestinal disorders and jaundice, with or without fever and cholangitis [1, 2]. Severe symptoms are more likely to represent a complication of cholecystectomy if they occur early or to express a definite treatable cause when compared with non-specific, dyspeptic or mild symptoms. A non-biliary aetiology of PCS should be suspected if no calculi or gallbladder abnormalities are found at cholecystectomy and symptoms are similar to those suffered pre-operatively [1]. Treatment for PCS is tailored to the specific cause and includes medication, sphincterotomy, biliary stenting, percutaneous drainage of bilomas and surgical revision for severe strictures [1–4].

Table 1

Main biliary causes of post-cholecystectomy syndrome (PCS) related to cholecystectomy. (Biliary malignancies are the most frequent causes of PCS unrelated to cholecystectomy [1])

Spatial variation in T1 of healthy human articular cartilage of the knee joint

The longitudiual relaxation time T₁ of native cartilage is frequently assumed to be constant. To redress this, the spatial variation of T₁ in unenhanced healthy human knee cartilage in different compartments and cartilage layers was investigated. Knees of 25 volunteers were examined on a 1.5 T MRI system. A three-dimensional gradient-echo sequence with a variable flip angle, in combination with parallel imaging, was used for rapid T₁ mapping of the whole knee. Regions of interest (ROIs) were defined in five different cartilage segments (medial and lateral femoral cartilage, medial and lateral tibial cartilage and patellar cartilage). Pooled histograms and averaged profiles across the cartilage thickness were generated. The mean values were compared for global variance using the Kruskal–Wallis test and pairwise using the Mann–Whitney U-test. Mean T₁ decreased from 900–1100 ms in superficial cartilage to 400–500 ms in deep cartilage. The averaged T₁ value of the medial femoral cartilage was 702±68 ms, of the lateral femoral cartilage 630±75 ms, of the medial tibial cartilage 700±87 ms, of the lateral tibial cartilage 594±74 ms and of the patellar cartilage 666±78 ms. There were significant differences between the medial and lateral compartment (p<0.01). In each cartilage segment, T₁ decreased considerably from superficial to deep cartilage. Only small variations of T₁ between different cartilage segments were found but with a significant difference between the medial and lateral compartments.MRI relaxation parameters are used to evaluate cartilage degradation. T₂ has been investigated extensively and has been demonstrated to vary with water and collagen content and with collagen orientation in the different cartilage layers [1–8].The quantification of the longitudiual relaxation time T₁ of native cartilage has received less attention. In experimental studies, native T₁ has been demonstrated to correlate with mechanical properties [9] and to depend upon the macromolecular structure of cartilage [10]. However, it is frequently assumed to be constant across cartilage [11–13]. A few studies have investigated the mean values of a single compartment (10, 14–19] but have not investigated the depth-dependent variation. To our knowledge, no study has systematically compared T₁ of unenhanced human knee cartilage in different cartilage layers and in different cartilage compartments in healthy volunteers.

Table 1

T₁ of healthy human articular cartilage in the knee joint

In vitro and in vivo repeatability of abdominal diffusion-weighted MRI

Objective

To study the in vitro and in vivo (abdomen) variability of apparent diffusion coefficient (ADC) measurements at 1.5 T using a free-breathing multislice diffusion-weighted (DW) MRI sequence.

Methods

DW MRI images were obtained using a multislice spin-echo echo-planar imaging sequence with b-values=0, 100, 200, 500, 750 and 1000 s mm⁻². A flood-field phantom was imaged at regular intervals over 100 days, and 10 times on the same day on 2 occasions. 10 healthy volunteers were imaged on two separate occasions. Mono-exponential ADC maps were fitted excluding b=0. Paired analysis was carried out on the liver, spleen, kidney and gallbladder using multiple regions of interest (ROIs) and volumes of interest (VOIs).

Results

The in vitro coefficient of variation was 1.3% over 100 days, and 0.5% and 1.0% for both the daily experiments. In vivo, there was no statistical difference in the group mean ADC value between visits for any organ. Using ROIs, the coefficient of reproducibility was 20.0% for the kidney, 21.0% for the gallbladder, 24.7% for the liver and 28.0% for the spleen. For VOIs, values fall to 7.7%, 6.4%, 8.6% and 9.6%, respectively.

Conclusion

Good in vitro repeatability of ADC measurements provided a sound basis for in vivo measurement. In vivo variability is higher and when considering single measurements in the abdomen as a whole, only changes in ADC value greater than 23.1% would be statistically significant using a two-dimensional ROI. This value is substantially lower (7.9%) if large three-dimensional VOIs are considered.Diffusion-weighted (DW) MRI is based on the Brownian motion of water in biological tissues [1,2]. The technique has played a preponderant role in neuro-imaging over the last two decades and it is known to detect small changes before they are apparent on anatomical imaging [3,4].In recent years DW MRI has been increasingly used in other parts of the body, demonstrating great diagnostic potential in cancer imaging. To date, DW MRI has been successfully used for tissue characterisation and tumour staging. However, the apparent diffusion coefficient (ADC) is a potential biomarker that could be used to monitor treatment response or evaluate post-therapeutic changes. Details of the clinical use of DW MRI can be found in the 2009 consensus paper [5] or in general and organ-specific review articles [6-8].While DW MRI is a potentially powerful tool in diagnostic oncology, the lack of uniform protocols for imaging and data analysis hinder its clinical implementation. Large differences in ADC values are reported in the literature depending on the acquisition parameters, in particular the choice of b-values (e.g. see [9] for ADC values in the kidney or 5] highlighted the importance of quality analysis, validation and reproducibility studies. Although there are some emerging reproducibility and repeatability data in the abdomen [15,19-22], a recent review by Taouli and Koh [7] highlights the need for further work in this area. Recently, coefficients of variability of around 14% were published for both solid tumours [22] and bone marrow [23]. Other studies seem to indicate that only ADC changes of over 27% [20] or 30% [21] are significant. Substantial variations in ADC values have also been found between different scanners and vendors [24-26], further highlighting the difficulty of setting up multicentre trials.

Table 1

Apparent diffusion coefficient values measured in normal liver at 1.5 T

Non-cutaneous melanoma: is there a role for 18F-FDG PET-CT?

Non-cutaneous melanomas (NCM) are diverse and relatively uncommon. They often differ from cutaneous melanomas in their epidemiology, genetic profile and biological behaviour. Despite the growing body of evidence regarding the utility of positron emission tomography (PET)/CT in cutaneous melanoma, the data on its use in NCM are scarce. In this review, we will summarize the existing literature and present cases from our experience with NCM to illustrate current knowledge on the potential role and limitations of fluorine-18 fludeoxyglucose PET/CT in NCM.Non-cutaneous melanomas (NCM) are classified according to origin: ocular, mucosal or unknown primary. Ocular melanomas may arise from the uvea or conjunctiva. Mucosal melanomas may originate from mucosal surfaces in the head and neck (oral cavity, nasal and paranasal sinuses) and gastrointestinal and genitourinary tracts. NCM are relatively rare, with ocular and mucosal melanomas accounting for only 5.5% and 1.3% of all melanomas in North America, respectively. The incidence of mucosal melanoma may vary according to the population studied (range, 0.2–10.0%) and is higher in Asian populations. By contrast, uveal melanomas are more common in Caucasians. 1,2 Staging and management of NCM varies by location and differs from cutaneous melanoma. In NCM, primary therapy consists of local resection, often with adjuvant radiotherapy. There may be a role for chemotherapy and immunotherapy; however, this approach has largely been extrapolated from experience with cutaneous tumours.

Table 1.

Comparison of cutaneous and non-cutaneous melanoma^1,2

Ability of 18-fludeoxyglucose positron emission tomography/CT to detect incidental cancer

Objective:

To determine the prevalence and clinical features of pathologically proven incidental cancer (IC) detected by whole-body fluorine-18 fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT, as well as the incidence of false-positive and false-negative results.

Methods:

We retrospectively reviewed reports derived from ¹⁸F-FDG PET/CT images of 3079 consecutive patients with known or suspected malignancies for 3 years. Discrete focal uptake indicating IC was identified from reports as well as pathological or clinical diagnoses, and the clinical courses were investigated. The false-positive result was defined as uptake indicating IC but not pathologically confirmed as malignant during follow-up. The false-negative result was defined as pathologically proven IC detected by another modality at initial clinical work-up or diagnosed during the follow-up period.

Results:

We found ¹⁸F-FDG uptake indicating IC in 6.7% of all patients, and IC was pathologically proven in 2.2% of all patients. The most common sites were the colon, lung and stomach. The median survival duration of patients with IC was 42 months. The results were false positive in 4.5% of all patients, and the results were false negative in 2.3% of all patients.

Conclusion:

¹⁸F-FDG PET/CT is a valuable tool for detecting IC. The rates of false-positive and false-negative results are within acceptable range.

Advances in knowledge:

This is the first report to describe the survival of patients with IC, and the detailed features of false-negative results at actual clinical settings.Integrated whole-body positron emission tomography (PET)/CT using the glucose analogue fluorine-18 fludeoxyglucose (¹⁸F-FDG) is an established modality for oncologic imaging. Combined metabolic and morphological images yielded by ¹⁸F-FDG PET/CT can provide accurate information on the staging, restaging and therapeutic monitoring of many common cancers.¹ Furthermore, ¹⁸F-FDG PET and PET/CT have the potential for cancer screening. Owing to the non-specific nature of ¹⁸F-FDG uptake, a wide range of malignant tumours can be visualized as incidental foci of hypermetabolism. For instance, new malignant tumours have been detected in asymptomatic individuals,² patients with head and neck cancer,³ oesophageal cancer⁴ and malignant lymphoma.⁵ Incidental focal ¹⁸F-FDG uptake within the gastrointestinal tract frequently represents malignant and pre-malignant tumours.^6,7 The detection of incidental cancer (IC) significantly impacts clinical oncological practice. Namely, the detection of a primary cancer can lead a patient to a new treatment, and the detection of a second primary cancer can lead a patient to a more suitable treatment.IC has been detected by ¹⁸F-FDG PET or PET/CT in the past decade.^8–15 8–13 The detection rate of IC ranges from 0.9% to 4.4%,^8–15 and a few reports have described a wider range (0.1–4.4%) of false-negative findings.^13–15 However, the survival of patients with IC has not been detailed. Differences in detection rates and other findings arise owing to many factors, including country, age, symptomatic or asymptomatic individuals, ¹⁸F-FDG PET or PET/CT, judgment criteria, method and period of follow-up.

Table 1.

Previous studies evaluating detection rate of incidental cancer (IC)

Uterine sarcomas: clinical presentation and MRI features

Uterine sarcomas are a rare heterogeneous group of tumors of mesenchymal origin, accounting for approximately 8% of uterine malignancies. They comprise leiomyosarcoma, endometrial stromal sarcoma, undifferentiated endometrial sarcoma, and adenosarcoma. Compared with the more common endometrial carcinomas, uterine sarcomas behave more aggressively and are associated with a poorer prognosis. Due to their distinct clinical and biological behavior, the International Federation of Gynecology and Obstetrics introduced a new staging system for uterine sarcomas in 2009, categorizing uterine carcinosarcoma as a variant of endometrial carcinoma, rather than a pure sarcoma. Magnetic resonance imaging (MRI) has a developing role in the assessment of these malignancies. Features such as tumor localization, irregular or nodular margins, necrosis, rapid growth, intense contrast enhancement, and restriction at diffusion-weighted imaging can suggest the diagnosis and help differentiate from more common leiomyomas and endometrial carcinoma. MRI is therefore extremely useful in preoperative detection and staging and, consequently, in determination of appropriate management. This pictorial review aims to discuss the clinical features of uterine sarcomas, as well as their most common appearances and distinct characteristics in MRI.Uterine sarcomas are a rare heterogeneous group of tumors of mesenchymal origin, accounting for approximately 8% of uterine malignancies (1), although they were thought to represent only 2% to 3% of all uterine tumors in the past (2). This increased incidence may be the result of improved diagnosis, as well as a true increase in an ageing population (1).These malignancies may originate from the smooth muscle in myometrium (leiomyosarcoma), from the endometrial stroma (endometrial stromal sarcoma [ESS] and undifferentiated endometrial sarcoma [UES]) or both (adenosarcoma) (3). According to the Gynecologic Oncology Group, uterine sarcomas can be classified into two categories: nonepithelial and mixed epithelial-nonepithelial, depending on the type of cancerous cell and its presumed tissue of origin (4).The clinical presentation of uterine sarcomas is nonspecific and dependent of histologic subtype. Classically, they present as a rapidly growing pelvic mass, which may be accompanied by vaginal bleeding and abdominal or pelvic pain (1, 5).Leiomyosarcoma is the most common histological variant of uterine sarcomas and is considered an aggressive tumor associated with poor prognosis, with a five-year survival rate ranging from 18.8% to 68%. ESS is relatively indolent, associated with long-term survival, but characterized by late recurrences (14%–60% of women). In contrast, UES has a very aggressive behavior and poor prognosis, with a five-year survival rate of 25%–55%. Adenosarcomas are rare mixed tumors (glandular and mesenchymal origin) with relatively low malignant potential and slow-growth pattern, with a five-year survival rate above 80% (6).The recognition of their distinct clinical and biological behavior when compared to endometrial carcinoma, which tend to behave more aggressively and are associated with a poorer prognosis, led the International Federation of Gynecology and Obstetrics (FIGO) to develop a new staging system for uterine sarcomas in 2009 (​and2).2). One important feature of the new staging system is that carcinosarcoma (formerly referred to as “malignant mixed Müllerian tumor”) is no longer considered as part of uterine sarcomas, being classified as a dedifferentiated or metaplastic form of endometrial carcinoma (7).

Table 1.

Staging for uterine leiomyosarcoma (7)

The value of image-guided intensity-modulated radiotherapy in challenging clinical settings

Objective

To illustrate the wider potential scope of image-guided intensity-modulated radiotherapy (IG-IMRT), outside of the “standard” indications for IMRT.

Methods

Nine challenging clinical cases were selected. All were treated with radical intent, although it was accepted that in several of the cases the probability of cure was low. IMRT alone was not adequate owing to the close proximity of the target to organs at risk, the risk of geographical miss, or the need to tighten planning margins, making image-guided radiotherapy an essential integral part of the treatment. Discrepancies between the initial planning scan and the daily on-treatment megavoltage CT were recorded for each case. The three-dimensional displacement was compared with the margin used to create the planning target volume (PTV).

Results

All but one patient achieved local control. Three patients developed metastatic disease but benefited from good local palliation; two have since died. A further patient died of an unrelated condition. Four patients are alive and well. Toxicity was low in all cases. Without daily image guidance, the PTV margin would have been insufficient to ensure complete coverage in 49% of fractions. It was inadequate by >3 mm in 19% of fractions, and by >5 mm in 9%.

Conclusion

IG-IMRT ensures accurate dose delivery to treat the target and avoid critical structures, acting as daily quality assurance for the delivery of complex IMRT plans. These patients could not have been adequately treated without image guidance.

Advances in knowledge

IG-IMRT can offer improved outcomes in less common clinical situations, where conventional techniques would provide suboptimal treatment.The recent advances in radiation delivery can improve tumour control probability and reduce treatment-related toxicity. The use of intensity-modulated radiotherapy (IMRT) allows for an improved radiation dose distribution compared with conventional techniques, ensuring safe dose escalation in selected cases. However, IMRT treatments are less forgiving of set-up inaccuracies owing to steep dose gradients. The integration of image-guided radiotherapy (IGRT) to the IMRT workflow (IG-IMRT) not only enables correction for set-up errors in real time but also permits tighter planning margins.Currently, there is limited evidence on the clinical benefits of IGRT. In addition, patients need to be clinically prioritised for IMRT, owing to limited capacity in the UK. This report illustrates the wider potential of IG-IMRT, where the integration of an IG-IMRT approach allows for radiation treatment which would be considered as non-feasible with conventional techniques.The success of radiotherapy in ablating a tumour depends principally on the total radiation dose, but this dose is limited by the tolerance of the surrounding normal tissues. Techniques such as three-dimensional conformal radiotherapy (3D-CRT) and, more recently, IMRT have allowed for a reduction in normal tissue dose, and therefore toxicity, for a given level of tumour dose. In turn, this may allow for dose escalation, with the expectation of a higher probability of tumour control. In some circumstances, IMRT enables treatment which might previously have been entirely impossible because of toxicity.There is now excellent evidence of the clinical value of IMRT in reducing toxicity by sparing the dose to the surrounding healthy tissue in various tumour sites [1-6]. These results are consistent with the fundamental proof of principle that better dose distributions lead to improved outcomes.One of the capabilities of IMRT is the ability to deliver very steep dose gradients where the target lies close to a critical normal structure. The dose may drop rapidly over just a few millimetres (e.g. 12 Gy over 3 mm), which may have important clinical value. However, it also makes IMRT less forgiving of set-up inaccuracies. In this situation, some form of image guidance to verify that the gradient is correctly located before treatment is desirable, for the dual goals of achieving an adequate target dose (avoiding geographical miss) and minimising the dose to normal tissues (avoiding excess toxicity). IGRT therefore acts as a quality assurance measure for the delivery of high-quality IMRT [7].The existence of discrepancies (positional errors) in patient set-up, resulting from a combination of systematic and random errors, is well understood [8,9]. For a mobile structure, such as the prostate, this also includes an important contribution from random day-to-day variation in the position of the prostate within the patient [10]. Image guidance has been revolutionised by the integration of online imaging capability on linear accelerators, with full software integration for image matching and positional correction. It allows for correction of positional discrepancies in real time, before treatment, so that each daily treatment can be accurately targeted, potentially allowing for tighter planning margins or greater security of target coverage. It also provides an opportunity for treatment adaptation based on changes in tumour volume or patient anatomy [11,12]. IGRT also has a role in quantifying positional discrepancies. It is likely that IGRT will at least contribute to more reliable target volume coverage, as well as a reduction in dose to the surrounding normal tissue [11,13]. In this way, IGRT is complementary to IMRT. However, caution is required, given that IGRT does not necessarily allow for planning target volume (PTV) margin reduction [14].Initial estimates for the expansion of the national IMRT programme suggested that 33% of radical fractions should be delivered with IMRT to maximise the clinical benefit from radiotherapy [15]. This figure of one-third was composed of 24% inverse-planned IMRT cases and 9% forward-planned IMRT cases. These figures have been helpful in developing the national service, but may need to be revised upwards. Significant progress is being made in the roll out of IMRT in the UK [16]. In general, the experience of centres treating with IMRT is that it has wider applicability, particularly when combined with IGRT [17-19]. Nevertheless, limitations in capacity are common, so it is necessary to prioritise those cases for which IG-IMRT is considered likely to give the greatest benefit. For tumours in the head and neck, the close proximity of the target to other structures makes IMRT an attractive option, and the evidence for reduction in long-term side effects with IMRT is most notable in this site. Image guidance is attractive for mobile internal targets such as the prostate [10,18]. Many other sites may also benefit from the combined techniques.The process of clinical prioritisation is a key component of IMRT service implementation [18,20-24]. This is simple for tumour sites where evidence of benefit exists. However, it may not be possible to generate such evidence for all tumour sites, nor should this be expected. In addition, there are situations in which it is impossible to achieve a worthwhile tumour dose without the use of IMRT. In our initial IG-IMRT series this amounted to 5% of cases [18].We report on a group of challenging clinical cases (CaseDiagnosisAge (years)Summary and reasoning for use of IG-IMRTF/U (months)Local recurrenceMetastatic diseaseOutcome1Pelvic Ewing''s sarcoma18Radical treatment, sparing normal tissue structures24NoNoAlive2Chest wall chondrosarcoma18Radical treatment for patient with normal anatomy, where radical treatment was not possible with CRT owing to OAR constraints24NoYesAlive3Prostate adenocarcinoma53Radical treatment for patient with challenging (abnormal) anatomy21NoNoAlive4Carcinoma of the larynx (post op)54Radical treatment for patient with challenging (abnormal) anatomy1NoNoDied5Prostate and rectal adenocarcinomas76Radical treatment of synchronous tumours simultaneously23NoYesDied6Carcinoma of the cervical oesophagus68Radical treatment following previous radiotherapy (occurrence of a different tumour)13NoNoAlive7Nasopharyngeal carcinoma60Radical retreatment (recurrence of the same tumour)15YesNoAlive8Carcinoma of the cervix38Radical retreatment (recurrence of the same tumour)15NoYesDied9Vertebral chordoma39Substitute for proton therapy in patients with metal reconstruction30NoNoAliveOpen in a separate windowCRT, conformal radiotherapy; F/U, follow-up; OAR, organ at risk; post op, post operation.There are different technical solutions for IG-IMRT and we used the TomoTherapy HiArt™ system (TomoTherapy Inc., Madison, WI) for IG-IMRT delivery. The concepts described here also apply to other platforms using rotational therapy.     

Mepilex Lite dressings for the management of radiation-induced erythema: a systematic inpatient controlled clinical trial

Erythema occurs in 80–90% of women treated for breast cancer with radiation therapy. There is currently no standard treatment for radiation-induced skin reactions. This study investigates the clinical efficacy of Mepilex Lite dressings in reducing radiation-induced erythema in women with breast cancer. A total of 28 patients were recruited; of these, 24 participants presented with 34 erythematous areas of skin for analysis. When erythema was visible, each affected skin area was randomly divided into two similar halves: one half was treated using Mepilex Lite dressings, the other half with standard aqueous cream. Skin reactions were assessed by the Radiation-Induced Skin Reaction Assessment Scale. We also evaluated any potential dose build-up by the dressings using a white water phantom, the dose distribution over the breast via thermoluminescent dosimeters (TLDs) and the surface skin temperature with an infrared thermographic scanner. Mepilex Lite dressings significantly reduced the severity of radiation-induced erythema compared with standard aqueous cream (p <0.001), did not affect surface skin temperature and caused only a small (0.5 mm) dose build-up. TLD measurements showed that the inframammary fold was exposed to significantly higher doses of radiation than any other breast region (p <0.0001). Mepilex dressings reduce radiation-induced erythema.Breast cancer is the most common malignancy for women in New Zealand. Most of these women will receive radiation therapy treatment, and skin reactions will occur in 80–90% of patients by treatment completion [1]. To date, there is no standard treatment for radiation-induced skin reactions and practice tends to be based on historical and anecdotal evidence [1–3]. A promising new range of Swedish silicon-foam skin dressings, Mepilex Lite (MV Bamford and Company Ltd, Lower Hutt, New Zealand and Mölnlycke Health Care Gothenburg, Sweden) is currently used in New Zealand for the treatment of burns and slow-healing wounds. This absorbent, self-adhesive dressing consists of a thin, flexible sheet of absorbent hydrophilic polyurethane foam bonded to a water vapour-permeable polyurethane film backing layer. The contact surface of the dressing is coated with a soft silicone adhesive layer without any added chemicals. It adheres to healthy skin, thus retaining the dressing in position but without causing trauma on removal, and provides a moist wound-healing environment. The material does not add or react to chemicals in or on the skin, does not stick to wounds and can be left on the skin for several days [1, 4].Preliminary case studies conducted in our department showed that Mepilex Lite dressings reduced the extent of all radiation-induced skin reactions. These results are consistent with previous case studies carried out in Scotland and Stockholm [1, 5]. The current study is the first clinical study that compares the clinical efficacy of Mepilex Lite dressings on the severity of radiation-induced erythema with a standard aqueous cream using the Radiation-Induced Skin Reaction Assessment Scale (RISRAS) (5, 6]. Because anecdotal evidence suggests that the dressings may have a cooling effect, we also determined their effect on surface skin temperature as well as the extent of dose build-up caused by the dressings if they were left on the patient during treatment.

Table 1

Radiation-Induced Skin Reaction Assessment Scale (RISRAS)

Ultrasonography-guided ethanol ablation of predominantly solid thyroid nodules: a preliminary study for factors that predict the outcome

Objectives

The aim of this study was to evaluate the success rate in ultrasonography-guided ethanol ablation (EA) of benign, predominantly solid thyroid nodules and to assess the value of colour Doppler ultrasonography in prediction of its success.

Methods

From January 2008 to June 2009, 30 predominantly solid thyroid nodules in 27 patients were enrolled. Differences in the success rate of EA were assessed according to nodule vascularity, nodule size, ratio of cystic component, amount of injected ethanol, degree of intranodular echo-staining just after ethanol injection and the number of EA sessions.

Results

On follow-up ultrasonography after EA for treatment of thyroid nodules, 16 nodules showed an excellent response (90% or greater decrease in volume) and 2 nodules showed a good response (50–90% decrease in volume) on follow-up ultrasonography. However, 5 nodules showed an incomplete response (10–50% decrease in volume) and 7 nodules showed a poor response (10% or less decrease in volume). Statistical analysis revealed a significant association of nodule vascularity (p = 0.002) and degree of intranodular echo-staining just after ethanol injection (p = 0.003) with a successful outcome; however, no such association was observed with regard to nodule size, ratio of cystic component, amount of infused ethanol and the number of EA sessions. No serious complications were observed during or after EA.

Conclusion

The success rate of EA was 60%, and nodule vascularity and intranodular echo-staining on colour Doppler ultrasonography were useful in predicting the success rate of EA for benign, predominantly solid thyroid nodules.Livraghi et al [1] used ultrasonography-guided ethanol ablation (EA) for the treatment of hyperfunctioning thyroid nodules; EA has since been established as the first-line treatment for benign cystic thyroid nodules, and may be considered an appropriate alternative to clinical follow-up, radioiodine therapy or thyroid surgery for treatment of autonomous functioning thyroid nodules (AFTNs) or toxic nodules. Advantages of EA include low risk, low cost, practicability in the outpatient clinic and ease of performance [2-14]. However, radioiodine therapy and surgery remain the treatments of choice for large toxic thyroid nodules [5,8,9,15].Following the initial use of EA in the treatment of benign cystic thyroid nodules [16], many published studies have reported appreciable efficacy of EA in the treatment of benign cystic thyroid nodules and recurrent cystic nodules [17-26]. However, published data regarding the EA of solid thyroid nodules have shown varying results, depending on nodule size, the volume of ethanol instilled and the presence of nodule toxicity (2-14]. Thus, the use of EA in the treatment of solid thyroid nodules has been limited owning to controversy over its efficacy and clinical indications. Several studies have attempted to determine factors that might be predictive of the effectiveness of EA in AFTNs or toxic nodules. These studies found that an initial nodule volume [5,8-10] and the presence of a cystic component making up more than 30% of the total volume are important factors in predicting a positive response to EA [14]. Despite these results, EA is rarely selected for the treatment of a solid thyroid nodule compared with the options of clinical follow-up, radioiodine therapy or surgery. Identification of factors that might aid in the accurate prediction of the success of EA in the treatment of solid thyroid nodules could result in more frequent clinical use of EA. To the best of our knowledge, no study of the feasibility of colour Doppler ultrasonography for predicting the success in EA of predominantly solid thyroid nodules has been conducted to date.

Table 1

The published data of ethanol ablation for solid thyroid nodules

Pulmonary arterial hypertension: an imaging review comparing MR pulmonary angiography and perfusion with multidetector CT angiography

Pulmonary hypertension (PH) is a progressive disease that leads to substantial morbidity and eventual death. Pulmonary multidetector CT angiography (MDCTA), pulmonary MR angiography (MRA) and MR-derived pulmonary perfusion (MRPP) imaging are non-invasive imaging techniques for the differential diagnosis of PH. MDCTA is considered the gold standard for the diagnosis of pulmonary embolism, one of the most common causes of PH. MRA and MRPP are promising techniques that do not require the use of ionising radiation or iodinated contrast material, and can be useful for patients for whom such material cannot be used. This review compares the imaging aspects of pulmonary MRA and 64-row MDCTA in patients with chronic thromboembolic or idiopathic PH.Pulmonary hypertension (PH) is an insidious and progressive disease that leads to substantial morbidity and eventual death. PH results from a number of diseases with different physiopathologies, treatments and prognoses [1]. One of the most frequent causes of PH is chronic thromboembolic pulmonary hypertension (CTEPH).The current classification of PH (2], resulted from a review of the previous classification developed at the 2003 3rd World Symposium in Venice, Italy. During the 4th World Symposium on PH, an international group of experts agreed to maintain the general philosophy and organisation of the Evian–Venice classifications. However, in response to a questionnaire regarding the previous classification, a majority (63%) of experts felt that modification of the Venice classification was required to accurately reflect information published in the past 5 years and to provide clarification in some areas [2].

Table 1

Classification of pulmonary hypertension according to the 4th World Symposium, Dana Point, CA, 2008 [2]

Can a revised paediatric radiation dose reduction CT protocol be applied and still maintain anatomical delineation,diagnostic confidence and overall imaging quality?

Objective:

To compare multidetector CT (MDCT) radiation doses between default settings and a revised dose reduction protocol and to determine whether the diagnostic confidence can be maintained with imaging quality made under the revised protocol in paediatric head, chest and abdominal CT studies.

Methods:

The study retrospectively reviewed head, chest, abdominal and thoracoabdominal MDCT studies, comparing 231 CT studies taken before (Phase 1) and 195 CT studies taken after (Phase 2) the implemented revised protocol. Image quality was assessed using a five-point grading scale based on anatomical criteria, diagnostic confidence and overall quality. Image noise and dose–length product (DLP) were collected and compared.

Results:

The relative dose reductions between Phase 1 and Phase 2 were statistically significant in 35%, 51% and 54% (p < 0.001) of head, chest and abdominal CT studies, respectively. There were no statistically significant differences in overall image quality score comparisons in the head (p = 0.3), chest (p = 0.7), abdominal (p = 0.7) and contiguous thoracic (p = 0.1) and abdominal (p = 0.2) CT studies, with the exception of anatomical quality in definition of bronchial walls and delineation of intrahepatic portal branches in thoracoabdominal CTs, and diagnostic confidence in mass lesion in head CTs, liver lesion (>1 cm), splanchnic venous thrombosis, pancreatitis in abdominal CTs, and emphysema and aortic dissection in thoracoabdominal CTs.

Conclusion:

Paediatric CT radiation doses can be significantly reduced from manufacturer''s default protocol while still maintaining anatomical delineation, diagnostic confidence and overall imaging quality.

Advances in knowledge:

Revised paediatric CT protocol can provide a half DLP reduction while preserving overall imaging quality.The use of CT has been rapidly increasing all over the world during the past two decades, driven by advanced technology and the invention of the multidetector CT (MDCT). Use of MDCT has risen 12-fold in the UK and 20-fold in the USA during this time, and the mean effective dose from all medical X-rays in the USA has increased 7-fold during this period.^1–3 6–11% of all CT examinations in developed countries are performed on children aged from 0 to 15 years.^2,4–6 The organ-absorbed doses reported in adult and paediatric patients undergoing single CT examination are considerably lower than the threshold for initiation of a deterministic effect and the estimated effective doses are still within the annual exposure dose from natural background radiation.⁷ The UK Radiation Protection Division of the Health Protection Agency, the US National Council on Radiological Protection and Measurement and the US National Academy of Sciences Biological Effects of Ionizing Radiation committees have proposed that, for doses <100 mSv, which is roughly equal to the dose range for multiple CT examinations, the radiation-induced cancers decrease linearly with decreasing dose with no threshold or a so called “linear no-threshold” model.^3,8,9 There was a linearly increasing risk for all solid cancers with increasing radiation dose and a higher radio sensitivity in children resulting in a larger attributable lifetime cancer risk in this patient group.^1,3Although the association of diagnostic medical radiation exposures in maternal pre-natal, children''s post natal and parental pre-conception periods with paediatric cancer risks are summarized in various studies, a CT scan-related cancer risk in children and adolescents has not been definitively proven.⁶ A retrospective cohort study by Pearce et al¹⁰ did, however, find a significant association between estimated cumulative radiation doses delivered by CT scan to the bone marrow and brain and subsequent increased risk of leukaemia and brain tumours in childhood.Diagnostic reference level (DRL) values are required for CT optimization, and these values are recommended by the International Commission on Radiological Protection; also each region or country is responsible for and authorized to enact details and implementation of their own DRLs.¹¹ Several age-based and weight-based DRLs for paediatric CT have been published.^12–17 General strategies for CT dose reduction in paediatric healthcare include such things as avoiding a CT scan if adequate clinical information can be obtained from ultrasound or MRI, avoiding multiphase examinations and designing CT protocols to minimize exposure time.¹⁸ Nowadays, many professional societies, regulators and manufacturers have been trying innovative new technologies for reducing radiation dose while maintaining optimal image quality.Two of the most commonly used image quality parameters in diagnostic imaging are high-contrast (spatial) resolution and low-contrast resolution. Spatial resolution is the ability to distinguish small objects close to one another on an image and is influenced by various factors such as focal spot size, detector width and ray, pixel size and properties of the reconstruction filter. Low-contrast resolution refers to the visibility of an object against the background. In the absence of artefacts, the low-contrast resolution scan is affected mostly by noise.^19,20 Although noise derivative is a quality index that is more relevant to assess image quality than image noise, it is difficult to translate in clinical practice.²¹ Image noise is measured by standard deviation (SD) of CT number, and it depends on milliamperes (mA), scan time, kilovoltage peak (kVp), patient size, pitch or table speed, slice thickness and reconstruction algorithm. If the milliampere–seconds value is reduced by 50%, the radiation dose will be reduced by the same amount, with an attendant noise increase of 41%, calculated by the equation (1/√2 = 1.41, a 41% increase). Tube voltage or beam energy has a direct influence on patient radiation dose. Reducing the peak kilovoltage results in a significant decrease in radiation dose owing to the square law relationship of these two values.^{19,20,22–25} Thus, the image noise and tissue contrast will be affected by adjusting kilovoltage; however, reduced peak tube potential is useful for chest, airway and skeletal studies owing to a high contrast-to-noise ratio requirement in imaging evaluation.¹⁸In our hospital (Songklanagarind Hospital, Hat Yai, Thailand), we began a revised CT dose reduction protocol in August 2010 that involved lowering kVp and mA, and using dose–length product (DLP) and DRLs based on the Nievelstein et al²³ protocol and national dose surveys from the UK and Canada^12,15 (CT scanned body partPhase 1

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Phase 2

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Age/body massCTDIkVpmAs with automatic tube current modulation^bAge/body massCTDIkVpmAHead<18 months20120150<6 months14.01209018 months to <6 years251202006 months to <3 years22.01201356–10 years321202503 to <6 years28.0120175    6 to <12 years32.0120200    >12 years50.0120315Chest<10 kg3.2120504 to <10 kg1.6809510 to <30 kg5.21208010 to <20 kg2.08012030–50 kg6.512010020 to <30 kg2.480140    30 to <40 kg2.812070    40 to <50 kg3.512090    50–64 kg4.3120110Abdomen<10 kg5.2120804 to <10 kg2.18013010 to <30 kg7.112011010 to <20 kg3.08018030–50 kg7.812012020 to <30 kg3.812090    30 to <40 kg4.1120105    40 to <50 kg4.9120125    50–64 kg5.9120150Open in a separate windowCTDI, CT dose index; kVp, kilovoltage peak; mA, milliamperes.^aReproduced from Nievelstein et al²³ with permission from Springer-Verlag.^bAutomatic tube current modulation in chest and abdominal CT.     

Multimodality imaging of primary extrahepatic portal vein obstruction (EHPVO): what every radiologist should know

Portal vein thrombosis (PVT) is a frequent complication of liver cirrhosis, but it can also occur as a primary vascular disorder amid absent liver disease. Extrahepatic portal vein obstruction (EHPVO) refers to the obstruction of the extrahepatic portal vein with or without involvement of the intrahepatic portal vein branches, splenic and/or superior mesenteric vein. It is a distinct disorder that excludes PVT occurring in concurrence with liver cirrhosis or hepatocellular carcinoma. The term “EHPVO” implies chronicity and is principally reserved for a long-standing condition characterized by cavernous transformation of the portal vein. The most characteristic imaging manifestation is the formation of portoportal collaterals (via the venous plexi of Petren and Saint) that allow hepatopetal flow. However, this collateral circulation is insufficient resulting in clinically significant pre-hepatic portal hypertension, wherein the liver function and structure remain preserved until late. Although the long-term (more than 10 years) survival with controlled variceal bleeding is up to 100%, affected individuals have an impaired quality of life owing to portal cavernoma cholangiopathy, hypersplenism, neurocognitive dysfunction and growth retardation. Imaging diagnosis is not always straightforward as the collaterals can also present as a tumour-like solid mass that can be inadvertently biopsied. Moreover, EHPVO has its implications for the biliary tree, arterial circulation, liver/splenic volumes and stiffness, which merit proper understanding but have not been so well described in literature. In this review, we present the complete spectrum of the vascular, biliary and visceral changes with a particular emphasis on what our medical/surgical hepatology colleagues need to know from us in the pre-operative and post-operative settings.Extrahepatic portal vein obstruction (EHPVO) refers to the obstruction of the extrahepatic portal vein with or without involvement of the intrahepatic branches, splenic vein (SV) and/or superior mesenteric vein (SMV). The term EHPVO implies chronicity and is principally reserved for a long-standing condition characterized by cavernous transformation of the portal vein. It is a distinct (primary) vascular disorder that excludes acute or chronic portal vein thrombosis (PVT) occurring in concurrence with liver cirrhosis or hepatocellular carcinoma.^1,2 Along with obliterative portal venopathy (OPV), EHPVO constitutes an important cause of non-cirrhotic (pre-hepatic) portal hypertension (NCPH), wherein the liver function and structure remain preserved until late. It has been proposed that an infection or a prothrombotic event occurring early in life (in a genetically predisposed individual) precipitates thrombosis of the main portal vein leading to EHPVO. By contrast, repetitive microthrombotic events occurring late in life, which involve smaller intrahepatic portal venous branches, are responsible for OPV.¹EHPVO is primarily a disorder of children and young adults and is the most common cause of paediatric portal hypertension (PHT) in developing countries. Also, it is the most common cause of gastrointestinal bleed in children and adolescents (68–84%). Whereas non-cirrhotic non-tumoral PVT in the Western world constitutes the second most frequent cause of PHT in adults, it is responsible for only 11% of cases of paediatric PHT.¹ The aetiology of EHPVO differs in paediatric and adult populations (1,2

Table 1.

Aetiology of extrahepatic portal vein obstruction