Congenital anorectal atresia: MR imaging of late post-operative appearances in adult patients with anal incontinence.

OBJECTIVES: To describe the MR imaging findings in adults presenting with anal incontinence following pull-through perineoplasty for anorectal atresia. METHODS: 15 adults (12 male, 3 female; age 22-52 years) with anal incontinence following a prior perineal pull-through procedure as an infant for anorectal atresia were identified retrospectively. MR imaging was performed using either an endoanal coil or body coil. MR images were reviewed by three observers who noted whether pelvic floor and sphincter muscles were present and, if so, whether they were thinned or not. Data were tabulated and raw frequencies determined. RESULTS: Images were unavailable for one patient, leaving 14 for analysis. Anal stenosis prevented endoanal coil placement in 5. The pull-through was anatomically correct in 12 (86 %) patients but was misdirected in 2. Thinned muscle was seen in 11 (79 %) patients. External sphincter thinning was commonest (present in 10 patients), with levator plate thinning least common (present in 4 patients). Only one patient had thinning of all muscle groups. CONCLUSION: MR imaging may be used to determine the extent and quality of residual pelvic floor and anal sphincter muscle in adults who have functional disability following pull-through perineoplasty for anorectal agenesis.

Synthetic osteochondral grafting of ankle osteochondral lesions.

BACKGROUND: The treatment of osteochondral lesions, especially those with a cystic component or those that have failed the standard arthroscopic procedures can be challenging. Synthetic grafts have several potential advantages over other second line treatments including the fact that only one operation is required and no other joint is violated. METHOD: We report the results of the first series of synthetic grafts used in the treatment of osteochondral lesions of the ankle with a minimum of one year follow up. RESULTS: There was significant improvement in the American Orthopaedic Foot & Ankle Society (AOFAS) Hindfoot and Ankle Osteoarthritis Scale (AOS) scores and all patients were satisfied with the results of surgery. Magnetic Resonance Imaging (MRI) scans at one year have demonstrated resolution of the bony cysts and surrounding bone marrow oedema but, worryingly, continued to show high signal on the T2 weighted images within the plugs themselves. Qualitative T2 mapping has suggested a fibrous rather than hyaline appearance of the cartilage portions of the plugs. CONCLUSIONS: The clinical results have been encouraging but more patients and longer follow up are required before firm conclusions can be drawn.

The role of the plain radiograph in the characterisation of soft tissue tumours.

A radiograph is often the first investigation to be requested when a patient presents with limb pain or a mass. Whilst we do not advocate that this is the only investigation to be employed in the evaluation of such patients, a working knowledge of the variety of abnormal findings that can present in the soft tissues on radiographs remains useful. We reviewed the radiographic findings of soft tissue masses from a prospectively compiled database of all such lesions presenting to a specialist orthopaedic oncology service over the past 8 years. Of the cohort of 1,058 individuals with a proven soft tissue tumour, 454 had had a radiograph taken of the affected area. Of these, 281 (62%) patients had a positive radiographic finding. The most common findings were a visible soft tissue mass (n = 141), the presence of calcification (n = 76), fat (n = 32) and evidence of bone involvement (n = 62). More than one finding was sometimes present in the same patient. These findings were present in both benign and malignant tumours. This review article describes the incidence and diagnostic relevance of these plain film findings for suspected soft tissue tumours.

Intramuscular schwannoma: clinical and magnetic resonance imaging features.

INTRODUCTION: Schwannomas that arise within the muscle plane are called intramuscular schwannomas. The low incidence of these tumours and the lack of specific clinical features make preoperative diagnosis difficult. Herein, we report our experience with intramuscular schwannomas. We present details of the clinical presentation, radiological diagnosis and management of these tumours. METHODS: Between January 2011 and December 2013, 29 patients were diagnosed and treated for histologically proven schwannoma at the National University Hospital, Singapore. Among these 29 patients, eight (five male, three female) had intramuscular schwannomas. RESULTS: The mean age of the eight patients was 40 (range 27-57) years. The most common presenting feature was a palpable mass. The mean interval between surgical treatment and the onset of clinical symptoms was 17.1 (range 4-72) months. Six of the eight tumours (75.0%) were located in the lower limb, while 2 (25.0%) were located in the upper limb. None of the patients had any preoperative neurological deficits. Tinel's sign was present in one patient. Magnetic resonance (MR) imaging showed that the findings of split-fat sign, low signal margin and fascicular sign were present in all patients. The entry and exit sign was observed in 4 (50.0%) patients, a hyperintense rim was observed in 7 (87.5%) patients and the target sign was observed in 5 (62.5%) patients. All patients underwent microsurgical excision of the tumour and none developed any postoperative neurological deficits. CONCLUSION: Intramuscular schwannomas demonstrate the findings of split-fat sign, low signal margin and fascicular sign on MR imaging. These findings are useful for the radiological diagnosis of intramuscular schwannoma.

Is the Apprehension Test Sufficient for the Diagnosis of Anterior Shoulder Instability in Young Patients without Magnetic Resonance Imaging (MRI)?

INTRODUCTION: The purpose of this study is to compare the sensitivities and positive predictive values (PPV) of the anterior apprehension test and magnetic resonance imaging (MRI) in the diagnosis of anterior labral tears in young patients with shoulder instability and to determine if surgery could be carried out without this investigation in selected patients. MATERIALS AND METHODS: We undertook a retrospective study of 168 patients aged between 15 and 30 years with a history of shoulder dislocation and compared the sensitivities and the PPV of the apprehension test with both MRI and magnetic resonance arthrograms (MRA) in the diagnosis of a Bankart lesion. The radiological investigations were interpreted by general practice radiologists and specialised musculoskeletal radiologists. All patients had their diagnosis confirmed by shoulder arthroscopy. RESULTS: Our results showed that the apprehension test was highly reliable when it was positive with a PPV of 96%. It was more sensitive than MRI in the diagnosis of a Bankart lesion. The clinical test was significantly better when a musculoskeletal radiologist interpreted the MRI. The MRA interpreted by a musculoskeletal radiologist had the highest rates of sensitivity in detecting Bankart lesions. The figure was similar to that for the apprehension test. There was no difference in the PPVs among the clinical test, the MRI and the MRA read by the 2 categories of radiologists. CONCLUSION: We conclude that a routine MRI may be unnecessary in evaluating a young patient with clinically evident anterior shoulder instability if the apprehension test is positive. A MRA that can be interpreted by a musculoskeletal radiologist will be the next best investigation if the clinical test is negative or equivocal.

Management of syndesmosis injuries in the elite athlete.

This article reviews the basics and evidence base thus far on syndesmosis injuries, focusing on its management in the elite sporting population. A syndesmosis injury or "high ankle sprain" is a significant injury, especially in the elite athlete. Among all ankle sprains, the syndesmotic injury is most predictive of persistent symptoms in the athletic population. Late diagnosis of unstable syndesmosis injuries leads to a poor outcome and delayed return to sports. A high index of suspicion and an understanding of the mechanism of injury is required to ensure an early diagnosis. Incomplete/inaccurate reduction leads to a poor outcome.

The meniscofibular ligament: an MRI study.

AIM: To describe the appearances and determine the prevalence of the meniscofibular ligament (ligamentum fibulare-MFibL) on MRI of the knee. SUBJECTS AND METHODS: Retrospective observational review of 160 knee MRI studies (152 patients) which was performed for a variety of clinical presentations over a period of 31 months. The images were assessed independently by two musculoskeletal radiology Fellows. RESULTS: The MFibL was optimally visualised on far lateral sagittal oblique fat suppressed PDW FSE images. The MFibL appeared as a curvilinear or straight, hypointense band of variable thickness extending between the inferior margin of the posterior third of the lateral meniscus and the fibular head. The ligament was demonstrated in 42.5% (n=68) of the total knee MRI studies, but this prevalence increased to 63% (56/88) in the presence of fluid in the posterolateral corner of the joint. CONCLUSION: The MFibL is commonly seen on far lateral fat suppressed oblique sagittal PD weighted MR images, particularly in the presence of fluid in the posterolateral corner, and should be recognised as a normal structure in the posterolateral corner of the knee.

CT colonography: optimisation, diagnostic performance and patient acceptability of reduced-laxative regimens using barium-based faecal tagging.

To establish the optimum barium-based reduced-laxative tagging regimen prior to CT colonography (CTC). Ninety-five subjects underwent reduced-laxative (13 g senna/18 g magnesium citrate) CTC prior to same-day colonoscopy and were randomised to one of four tagging regimens using 20 ml 40%w/v barium sulphate: regimen A: four doses, B: three doses, C: three doses plus 220 ml 2.1% barium sulphate, or D: three doses plus 15 ml diatriazoate megluamine. Patient experience was assessed immediately after CTC and 1 week later. Two radiologists graded residual stool (1: none/scattered to 4: >50% circumference) and tagging efficacy for stool (1: untagged to 5: 100% tagged) and fluid (1: untagged, 2: layered, 3: tagged), noting the HU of tagged fluid. Preparation was good (76-94% segments graded 1), although best for regimen D (P = 0.02). Across all regimens, stool tagging quality was high (mean 3.7-4.5) and not significantly different among regimens. The HU of layered tagged fluid was higher for regimens C/D than A/B (P = 0.002). Detection of cancer (n = 2), polyps > or =6 mm (n = 21), and < or =5 mm (n = 72) was 100, 81 and 32% respectively, with only four false positives > or =6 mm. Reduced preparation was tolerated better than full endoscopic preparation by 61%. Reduced-laxative CTC with three doses of 20 ml 40% barium sulphate is as effective as more complex regimens, retaining adequate diagnostic accuracy.

Colonic polyps: effect of attenuation of tagged fluid and viewing window on conspicuity and measurement--in vitro experiment with porcine colonic specimen.

PURPOSE: To investigate effect of attenuation of tagged fluid and viewing window on polyp conspicuity and measurement with porcine colonic specimen. MATERIALS AND METHODS: Eleven (3-10-mm-diameter) polyps were created in porcine colon and the specimen submerged in saline. Four-detector row CT was performed after gas distension and after filling with six barium sulfate suspensions (attenuation, 100-1000 HU). Two readers independently measured maximal two-dimensional polyp diameter on each data set with the following four viewing windows and window levels and window widths, respectively: colon (-150 HU, 1500 HU), lung (-500 HU, 1500 HU), bone (500 HU, 2500 HU), and abdomen (40 HU, 400 HU). In consensus, polyp conspicuity (compared with air data set) was assigned a grade of 1-4 for each viewing window (grade 1, not seen or barely visible; grade 4, optimally seen). For statistical analysis, conspicuity grades were collapsed to a two-point scale. Data were analyzed with Mann-Whitney, Kruskal-Wallis, and chi2 tests. RESULTS: Accuracy of polyp measurement was independent of viewing window for attenuation of tagged fluid of 100-300 HU but differed significantly for 500-1000 HU (P < .001); that for colonic and bone viewing windows was superior (median size difference, 1.0 mm; interquartile range, 0.5-1.5). Conspicuity differed significantly according to viewing window at all attenuation values (P < .001). For 100-300 HU with abdominal viewing window, 83% (24 of 29) of observations were assigned grade 3 or 4 (best). For 500-1000 HU with bone viewing window, 94% (30 of 32) of observations were assigned grade 3 or 4 (superior). Overall conspicuity was best with bone viewing windows at 700 HU. CONCLUSION: Polyp conspicuity and measurement in tagged data sets were optimized at 700 HU with bone viewing windows. At less than 300 HU, conspicuity improved with abdominal viewing windows.

Automated insufflation of carbon dioxide for MDCT colonography: distension and patient experience compared with manual insufflation.

OBJECTIVE: The purpose of our study was to compare the effects of automated and manual carbon dioxide insufflation before CT colonography on distention and patient acceptance. SUBJECTS AND METHODS: One hundred forty-one symptomatic subjects underwent CT colonography using either an automated device (n = 47) or a manual method (n = 94) for carbon dioxide insufflation. CT data sets were assessed retrospectively in consensus by two blinded observers who graded distention for six colonic segments using a 4-point scale. An additional assessment of the overall clinical adequacy of distention (yes/no) was also made, and any learning curve was sought. Each patient completed a validated 24-point patient questionnaire reflecting patient satisfaction and discomfort. Distention scores, clinical adequacy, and questionnaire responses were analyzed using ordered logistic regression, Fisher's exact test, and the Mann-Whitney test statistic, respectively. RESULTS: Automated insufflation significantly improved distention overall (p = 0.001). For individual segments, distention was significantly improved in the sigmoid (p = 0.007) and descending (p < 0.001) colons when the patient was supine; and in the sigmoid (p = 0.02), descending (p = 0.001), and transverse (p = 0.02) colons when supine and prone positions were combined. No significant difference was seen in the clinical adequacy of distention, nor was there evidence of any learning curve for either insufflation method. Subjects were more weary after automated insufflation (p = 0.03), but no significant difference was seen for the remaining 23 questionnaire items or for feelings of bloating or discomfort. CONCLUSION: Automated carbon dioxide insufflation significantly improves colonic distention compared with manual insufflation. Benefit is greatest in the left colon, particularly when the patient is supine. Patient acceptance is similar to that for manual insufflation.

Reader error during CT colonography: causes and implications for training.

This study investigated the variability in baseline computed tomography colonography (CTC) performance using untrained readers by documenting sources of error to guide future training requirements. Twenty CTC endoscopically validated data sets containing 32 polyps were consensus read by three unblinded radiologists experienced in CTC, creating a reference standard. Six readers without prior CTC training [four residents and two board-certified subspecialty gastrointestinal (GI) radiologists] read the 20 cases. Readers drew a region of interest (ROI) around every area they considered a potential colonic lesion, even if subsequently dismissed, before creating a final report. Using this final report, reader ROIs were classified as true positive detections, true negatives correctly dismissed, true detections incorrectly dismissed (i.e., classification error), or perceptual errors. Detection of polyps 1-5 mm, 6-9 mm, and > or =10 mm ranged from 7.1% to 28.6%, 16.7% to 41.7%, and 16.7% to 83.3%, respectively. There was no significant difference between polyp detection or false positives for the GI radiologists compared with residents (p=0.67, p=0.4 respectively). Most missed polyps were due to failure of detection rather than characterization (range 82-95%). Untrained reader performance is variable but generally poor. Most missed polyps are due perceptual error rather than characterization, suggesting basic training should focus heavily on lesion detection.

Quantitative colorectal cancer perfusion measurement using dynamic contrast-enhanced multidetector-row computed tomography: effect of acquisition time and implications for protocols.

OBJECTIVE: To determine the effect of acquisition time on quantitative colorectal cancer perfusion measurement. METHODS: Dynamic contrast-enhanced computed tomography (CT) was performed prospectively in 10 patients with histologically proven colorectal cancer using 4-detector row CT (Lightspeed Plus; GE Healthcare Technologies, Waukesha, WI). Tumor blood flow, blood volume, mean transit time, and permeability were assessed for 3 acquisition times (45, 65, and 130 seconds). Mean values for all 4 perfusion parameters for each acquisition time were compared using the paired t test. RESULTS: Significant differences in permeability values were noted between acquisitions of 45 seconds and 65 and 130 seconds, respectively (P=0.02, P=0.007). There was no significant difference for values of blood volume, blood flow, and mean transit time between any of the acquisition times. CONCLUSIONS: Scan acquisitions of 45 seconds are too short for reliable permeability measurement in the abdomen. Longer acquisition times are required.