Ryan K. L. Lee

Knowledge of radiation exposure in common radiological investigations: a comparison between radiologists and non-radiologists

Background Radiological examinations are commonly requested for patients to aid clinical diagnosis. However, many doctors do not realise how much radiation dosage their patients are exposed to during radiological investigations. This study aims to assess and compare the knowledge of radiologists and non-radiologists about radiation doses of common radiological investigations. Methods A prospective questionnaire study of doctors about the dosage of commonly performed radiological investigations in a university teaching hospital in Hong Kong. Participants were asked to indicate the average dose of radiation (in mSv) for a standard chest x-ray exposure. Doctors were then asked to estimate the doses of radiation (measured in chest x-ray equivalents) for various radiological procedures. The results of radiologists and non-radiologists were compared. Results 158 doctors (25 radiologists and 133 non-radiologists) completed the questionnaire. The overall accuracy was 40% for radiologists and 16% for non-radiologists. One-third of non-radiologists could not distinguish radiological examinations with or without ionising radiation. No non-radiologists correctly stated the radiation dose (in mSv) of a conventional chest x-ray, and 77% underestimated the dose of radiological examinations. For radiologists, only 32% were correct for the radiation dose of a conventional chest x-ray while 7% underestimated the radiation doses. Conclusion Knowledge of radiation doses of investigation is generally inadequate among radiologists, and particularly poor in non-radiologists. Underestimation of radiation doses may expose patients to increasing radiological investigation and exposure to radiation hazards. Awareness of the radiation hazard of radiological examinations should be raised among medical professionals.

Diagnostic capability of low- versus high-field magnetic resonance imaging for lumbar degenerative disease.

Study Design. Cohort study. Objective. To investigate the diagnostic capability of low-field magnetic resonance imaging (MRI) compared with high-field MRI for degenerative disease of the lumbar spine. Summary of Background Data. Low-field MRI has several advantages over high-field magnetic resonance systems (easier installation, lower purchase, and maintenance cost). The diagnostic capability of low-field MRI for degenerative disease of the lumbar spine has not been compared with that of high-field MRI. Methods. Hundred patients (mean age: 56.3 yr, range: 32–80; F:M = 59:41) with neurogenic claudication or sciatica were studied. All patients underwent MRI of the lumbar spine on both low-field (0.25T) and high-field (1.5T or 3.0T) magnetic resonance systems. Intervertebral disc herniation, central canal, lateral recess, and exit foraminal stenosis as well as nerve root compression at L3–L4, L4–L5, and L5–S1 were evaluated by 2 radiologists for both low- and high-field systems using established reliable grading systems. Results. There was excellent agreement between low- and high- field MRI with regard to grading the presence and severity of disc herniation (r = 0.92–0.94; P < 0.05), central canal stenosis (r = 0.89–0.91; P < 0.05), lateral recess stenosis (r = 0.81–0.87; P < 0.05), and exit foramen stenosis (r = 0.81–0.89; P < 0.05). Descending or exiting nerve root compression occurred in 52% of patients at L3–L4, L4–L5, or L5–S1 levels, with good agreement between low-field and high-field MRI (r = 0.71–0.76; P < 0.05) for nerve root compression. Conclusion. Excellent reliability between low- and high- field MRI was found for most features of lumbar disc degeneration, with good agreement for nerve root compression. 0.25T MRI was more susceptible to motion artifact, probably due to longer scanning time. Level of Evidence: 3

CT-Guided Bone Biopsy With a Battery-Powered Drill System: Preliminary Results

OBJECTIVE Standard percutaneous bone biopsy involves manual needle insertion. Recently, a battery-powered needle drilling biopsy system (OnControl) has been introduced. We report our experience using this drill biopsy system for CT-guided percutaneous bone biopsy in 25 patients. CONCLUSION CT-guided percutaneous biopsy using the OnControl bone access system is a safe, quick, and effective method for sampling bone lesions visible on CT.

Occult pneumothoraces in Chinese patients with significant blunt chest trauma: Radiological classification and proposed clinical significance

BACKGROUND An occult pneumothorax (OP) is a pneumothorax not seen on a supine chest X-ray (CXR) but detected on abdominal or thoracic computed tomography (CT) scanning. With the increasing use of CT in the management of significantly injured trauma patients, more OPs are being detected. The aim of this study was to classify OPs diagnosed on thoracic CT (TCT) and correlate them with their clinical significance. METHODS Retrospective analysis of prospectively collected trauma registry data. Total 36 (N=36) consecutive significantly injured trauma patients admitted through the emergency department (ED) who sustained blunt chest trauma and underwent TCT between 1 January 2007 and 31 December 2008 were included. OP was defined as the identification (by a consultant radiologist) of a pneumothorax on TCT that had not been detected on supine CXR. OPs were classified by laterality (unilateral/bilateral) and location (apical, basal, non apical/basal). The size of pneumothoraces, severity of injury [including number of associated thoracic injuries and injury severity score (ISS)], length of hospital stay and mortality were compared between groups. The need for tube thoracostomy and clinical outcome were also analysed. RESULTS Patients with bilateral OPs (N=8) had significantly more associated thoracic injuries (median: 2 vs. 1, p=0.01), higher ISS (median: 35 vs. 23, p=0.02) and longer hospital stay (median: 20 days vs. 11 days, p=0.01) than those with a unilateral OP (N=28). Basal OPs (N=7) were significantly larger than apical (N=10) and non-apical/basal Ops (N=11). Basal OPs were associated with significantly more associated thoracic injuries (median: 2 vs. 1, p=0.01), higher ISS (median: 35 vs. 25, p=0.04) and longer hospital stays (median: 23 days vs. 17 days, p=0.02) than apical Ops, which had higher ISS (median: 35 vs. 25, p=0.04) and longer hospital stays (median: 23 days vs. 15 days, p=0.02) than non-apical/basal OPs. Non-apical/basal OPs were associated with more related injuries (median: 2 vs. 1, p=0.02) than apical OPs. All apical and non-apical/basal OPs were successfully managed expectantly without associated mortality. CONCLUSION This TCT classification of OP is proposed to help clinicians to decide on subsequent management of the OP. Basal OPs are significantly larger in size, and both basal and bilateral OPs are associated with higher severity of injury and longer hospital stay. These groups of patient may benefit from prophylactic tube thoracostomy instead of conservative treatment. On the other hand, apical and non-apical/basal groups is smaller in size, less severely injured and thus can be successfully managed expectantly.

Wrist Traction During MR Arthrography Improves Detection of Triangular Fibrocartilage Complex and Intrinsic Ligament Tears and Visibility of Articular Cartilage.

OBJECTIVE The purpose of this study was to assess the effects of traction during MR arthrography of the wrist on joint space widening, cartilage visibility, and detection of tears of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments. SUBJECTS AND METHODS A prospective study included 40 wrists in 39 patients (25 men, 14 women; mean age, 35 years). MR arthrography was performed with a 3-T MRI system with and without axial traction. Two radiologists independently measured wrist and carpal joint space widths and semiquantitatively graded articular cartilage visibility. Using conventional arthrography as the reference standard and working in consensus, they assessed for the presence of tears of the TFCC, lunotriquetral ligament (LTL), and scapholunate ligament (SLL). Visibility of a tear before traction was compared with visibility after traction. RESULTS With traction, all joint spaces in the wrist and carpus were significantly widened (change, 0.15-1.01 mm; all p < 0.006). Subjective cartilage visibility of all joint spaces improved after traction (all p ≤ 0.048) except for that of the radioscaphoid space, which was well visualized even before traction. Conventional arthrography depicted 24 TFCC tears, seven LTL tears, and three SLL tears. The accuracy of tear detection improved after traction for the TFCC (98% after traction vs 83% before traction), the LTL (100% vs 88%), and the SLL (100% vs 95%). Tear visibility improved after traction for 54% of TFCC tears, 71% of LTL tears, and 66% of SLL tears. CONCLUSION Wrist MR arthrography with axial traction significantly improved the visibility of articular cartilage and the detection and visibility of tears of the TFCC and intrinsic ligaments. The results favor more widespread use of traction during MR arthrography of the wrist.

Pathological fracture as the presenting feature in pediatric osteosarcoma

Pathological fracture is an uncommon presentation in patients with long bone osteosarcoma.

Anterior cruciate ligament bundle measurement by MRI.

ObjectiveAn accurate in vivo method of measuring dimensions of the anteromedial (AM) and posterolateral (PL) anterior cruciate ligament (ACL) bundles has not been established. The purpose of this study was to measure each individual bundle using double oblique axial MR imaging of the ACL, to compare this with cadaveric measurements, and to investigate the range of measurements seen in normal subjects.Materials and methodsIn five cadaveric knees, measurements obtained of the proximal, middle, and distal segments of each ACL bundle from double oblique axial MR images were compared with direct measurements following anatomical dissection. Thereafter, the size of both bundles from 24 normal knees was measured using an identical MR technique. Inter-observer variation was calculated using intraclass correlation.ResultsACL bundle measurement in the cadaveric knees had a strong correlation (r = 0.93) with measurements obtained following anatomical dissection. No significant difference existed between measurements obtained from cadaveric knees and living normal subjects (p > 0.05). Interobserver correlation for MR measurements was excellent (R = 0.92–0.93). Overall, the long and short axis of the AM bundle were significantly larger than those of the PL bundle (p < 0.05). Also, men showed significantly larger AM and PL bundles than women (p < 0.05). Bundle size was not related to age or knee dominance.ConclusionThe individual ACL bundles can be accurately measured on double oblique axial MR imaging. The AM bundle is larger in caliber than the PL bundle. Both bundles are larger in men than in women and there is no significant side-to side difference.

Encephalocraniocutaneous lipomatosis: a rare case with development of diffuse leptomeningeal lipomatosis during childhood

We describe the uncommon development of leptomeningeal lipomatosis in a girl with encephalocraniocutaneous lipomatosis (ECCL). Leptomeningeal involvement had not been present at 2 years of age, but was demonstrated on CT and MRI at 10 years of age. Our case demonstrates follow-up neuroimaging features of ECCL that may be helpful to radiologists in suggesting the correct diagnosis, as ocular and cutaneous lesions may be non-specific clinically. The developmental nature of leptomeningeal involvement in our case suggests that close clinical and radiological follow-up is important in children with suspected or established ECCL.

Atypical Intracranial Epidermoid Cysts: Rare Anomalies with Unique Radiological Features

Epidermoid cysts are benign slow growing extra-axial tumours that insinuate between brain structures, while their occurrences in intra-axial or intradiploic locations are exceptionally rare. We present the clinical, imaging, and pathological findings in two patients with atypical epidermoid cysts. CT and MRI findings for the first case revealed an intraparenchymal epidermoid cyst that demonstrated no restricted diffusion. The second case demonstrated an aggressive epidermoid cyst that invaded into the intradiploic spaces, transverse sinus, and the calvarium. The timing of ectodermal tissue sequestration during fetal development may account for the occurrence of atypical epidermoid cysts.

Morphologic Change in Computed Tomography of Aldosterone-Producing Adenoma After Radiofrequency Ablation

Objective To evaluate the morphologic changes of aldosterone-producing adenoma (APA) on computed tomography (CT) before and after radiofrequency ablation (RFA) and to assess the factors that are important in determining successful complete ablation of these tumours. Method Between August 2004 and August 2011, 24 consecutive patients with APA undergoing CT-guided percutaneous RFA were identified from our prospective database. The pre-RFA and post-RFA CT appearances of these APAs that showed positive biochemical response were reviewed retrospectively for their 3-dimensional size, tumour volume, and CT attenuation in terms of Hounsfield units (HU). A comparison of these parameters before and after RFA was performed. Results In this study, there were 23 APAs in these 24 patients that showed biochemical cure of primary aldosteronism after RFA. When comparing post-RFA to pre-RFA CTs, there was no significant change in tumour size (14.5 mm vs 14.6 mm: P = .83) and tumour volume (1.55 cm3 vs 1.59 cm3; P = .41) after RFA. In nonenhanced CT images, there was no significant reduction in HU from pre-RFA to post-RFA measurements (4.4 HU vs 7.9 HU; P = .52). In contrast-enhanced CTs, there was a significant drop in HU after RFA (from 48.3 HU to 14.7 HU; P = .03). None of the included cases showed a focal region of contrast enhancement to suggest residual tumour. Conclusion A change in tumour size, tumour volume, and HU in nonenhanced CT were unreliable in defining radiologic treatment success. Only changes in HU in contrast-enhanced CT was useful in confirming a positive treatment response after RFA for APA.