Does Courvoisier's sign stand the test of time?

AIM: To investigate the validity of Courvoisier's sign, in the age of cross-sectional imaging and image analysis software by objectively measuring gallbladder volumes at magnetic resonance cholangiopancreatography (MRCP) in patients with and without biliary obstruction and to assess whether gallbladder volume is more significantly increased in patients with gallstone-related rather than non-gallstone-related biliary obstruction. MATERIALS AND METHODS: All MCRP investigations that were performed at a tertiary hepatobiliary centre over a 2-year period were analysed. The information recorded included the presence or absence of gallbladder stones as well as the presence and type of common bile duct (CBD) disease. Gallbladder volume was calculated from MRCP studies using image analysis software. RESULTS: Three hundred and ninety-four of 645 examined MRCPs (61.1%) were eligible for analysis. A statistically significant difference in mean gallbladder volume existed between the summated obstructive and non-obstructive groups (p < 0.001). In addition, a significant difference existed in mean gallbladder volume between those with CBD stones and non-gallstone CBD obstruction (p = 0.03). CONCLUSION: A significant difference was observed in gallbladder volumes in the group with biliary obstruction from choledocholithiasis compared with the group with biliary obstruction from other causes. Thus, objective measurement of gallbladder volume from modern cross-sectional imaging studies appears to validate Courvoisier's sign as a valuable clinical sign, which could be applied to modern imaging studies in distinguishing different causes of biliary obstruction in the jaundiced patient.

Reversible posterior leukoencephalopathy induced by carboplatin and etoposide.

Reversible posterior leukoencephalopathy syndrome (RPLS) is a rare neurologic condition characterised by specific clinical and radiologic findings. It usually manifests subacutely as insidious onset of headache, visual disturbance, altered consciousness and seizures in association with MRI findings of posterior white matter vasogenic oedema. RPLS has been reported in a wide variety of clinical settings. Hypertension, eclampsia, pre-eclampsia, renal impairment, autoimmune conditions and cytotoxic drugs are all cited as aetiologic variables. RPLS, albeit rare, is an important entity for physicians to be aware of as early recognition, and prompt intervention is critical to ensure resolution of the neurological deficit. We describe the case of a 69-year-old lady who collapsed with seizure activity after receiving carboplatin and etoposide chemotherapy for small cell lung cancer. In our opinion, the clinical and radiological courses are typical of RPLS. RPLS has rarely been reported secondary to this chemotherapy regimen, and the purpose of this report is to add to the literature and highlight the association between RPLS and cytotoxic chemotherapy.

Spontaneous intracranial hypotension.

INTRODUCTION: Spontaneous/primary intracranial hypotension is characterised by orthostatic headache and is associated with characteristic magnetic resonance imaging findings. CASE REPORT: We present a case report of a patient with typical symptoms and classical radiological images. DISCUSSION: Spontaneous intracranial hypotension is an under-recognised cause of headache and can be diagnosed by history of typical orthostatic headache and findings on MRI brain.

Sedation with oral chloral hydrate in children undergoing MRI scanning.

In the absence of a general anaesthetic facility for MRI scanning in children, we introduced a sedation protocol using chloral hydrate. Our aim was to evaluate the success and safety of our protocol. This was a retrospective study enrolling 36 children over a 7 month period. The overall success rate was 86% with no child experiencing respiratory complications. In those less than one year, the success rate was 100%, aged 1-5 years 91%, with 50% successful at 80 mg/kg and 50% at 100 mg/kg dose. For children greater than 5 years of age the success rate was 70%. 92% of developmentally normal children and 83% of developmentally delayed children were successfully sedated. Success rates were poorer in children older than 5 years and in those with developmental delay. Our findings suggest that this protocol could be safely used in units where general anaesthetic facilities are unavailable for MRI and for other radiological investigations.

Improved quantification of left ventricular mass based on endocardial and epicardial surface detection with real time three dimensional echocardiography.

OBJECTIVE: To develop a technique for volumetric analysis of real time three dimensional echocardiography (RT3DE) data aimed at quantifying left ventricular (LV) mass and to validate the technique against magnetic resonance (MR) assumed as the reference standard. DESIGN: RT3DE, which has recently become widely available, provides dynamic pyramidal data structures that encompass the entire heart and allows four dimensional assessment of cardiac anatomy and function. However, analysis techniques for the quantification of LV mass from RT3DE data are fundamentally two dimensional, rely on geometric modelling, and do not fully exploit the volumetric information contained in RT3DE datasets. Twenty one patients underwent two dimensional echocardiography (2DE), RT3DE, and cardiac MR. LV mass was measured from 2DE and MR images by conventional techniques. RT3DE data were analysed to semiautomatically detect endocardial and epicardial LV surfaces by the level set approach. From the detected surfaces, LV mass was computed directly in the three dimensional space as voxel counts. RESULTS: RT3DE measurement was feasible in 19 of 21 patients and resulted in higher correlation with MR (r = 0.96) than did 2DE (r = 0.79). RT3DE measurements also had a significantly smaller bias (-2.1 g) and tighter limits of agreement (2SD = +/-23 g) with MR than did the 2DE values (bias (2SD) -34.9 (50) g). Additionally, interobserver variability of RT3DE (12.5%) was significantly lower than that of 2DE (24.1%). CONCLUSIONS: Direct three dimensional model independent LV mass measurement from RT3DE images is feasible in the clinical setting and provides fast and accurate assessment of LV mass, superior to the two dimensional analysis techniques.

Minimal preparation computed tomography instead of barium enema/colonoscopy for suspected colon cancer in frail elderly patients: an outcome analysis study.

AIM: To evaluate the efficacy of minimal preparation computed tomography (MPCT) in diagnosing clinically significant colonic tumours in frail, elderly patients. MATERIALS AND METHODS: A prospective study was performed in a group of consecutively referred, frail, elderly patients with symptoms or signs of anaemia, pain, rectal bleeding or weight loss. The MPCT protocol consisted of 1.5 l Gastrografin 1% diluted with sterile water administered during the 48 h before the procedure with no bowel preparation or administration of intravenous contrast medium. Eight millimetre contiguous scans through the abdomen and pelvis were performed. The scans were double-reported by two gastrointestinal radiologists as showing definite (>90% certain), probable (50-90% certain), possible (<50% certain) neoplasm or normal. Where observers disagreed the more pessimistic of the two reports was accepted. The gold standard was clinical outcome at 1 year with positive end-points defined as (1) histological confirmation of CRC, (2) clinical presentation consistent with CRC without histological confirmation if the patient was too unwell for biopsy/surgery, and (3) death directly attributable to colorectal carcinoma (CRC) with/without post-mortem confirmation. Negative end-points were defined as patients with no clinical, radiological or post-mortem findings of CRC. Patients were followed for 1 year or until one of the above end-points were met. RESULTS: Seventy-two patients were included (mean age 81; range 62-93). One-year follow-up was completed in 94.4% (n=68). Mortality from all causes was 33% (n=24). Five histologically proven tumours were diagnosed with CT and there were two probable false-negatives. Results were analysed twice: assuming all CT lesions test positive and considering "possible" lesions test negative [brackets] (95% confidence intervals): sensitivity 0.88 (0.47-1.0) [0.75 (0.35-0.97)], specificity 0.47 (0.34-0.6) [0.87 (0.75-0.94)], positive predictive value 0.18 [0.43], negative predictive value 0.97 [0.96], positive likelihood ratio result 1.6 [5.63], negative likelihood ratio result 0.27 [0.29], kappa 0.31 [0.43]. Tumour prevalence was 12%. A graph of conditional probabilities was generated and analysed. A variety of unsuspected pathology was also found in this series of patients. CONCLUSIONS: MPCT should be double-reported, at least initially. "Possible" lesions should be ignored. Analysis of the graph of conditional probability applied to a group of frail, elderly patients with a high mortality from all causes (33% in our study) suggests: (1) if MPCT suggests definite or probable carcinoma, regardless of the pre-test probability, the post-test probability is high enough to warrant further action, (2) frail, elderly patients with a low pre-test probability for CRC and a negative MPCT should not have further investigation, (3) frail, elderly patients with a higher pre-test probability of CRC (such as those presenting with rectal bleeding) and a negative MPCT should have either double contrast barium enema (DCBE) or colonoscopy as further investigations or be followed clinically for 3-6 months. MPCT was acceptable to patients and clinicians and may reveal significant extra-colonic pathology.

Automated segmentation of colonic walls for computerized detection of polyps in CT colonography.

PURPOSE: A new method for fully automated segmentation of the colonic walls in volumetric CT data was developed for limitation of the search space in computerized detection of polyps. METHOD: For reliable segmentation, an anatomy-oriented approach was used, in which several anatomical structures are segmented in addition to the colon for utilization of their properties. RESULTS: The segmentation method was validated by use of 14 data sets, consisting of cases positive for colonic polyps. We found that the segmented colonic walls included all of the polyps. A subjective rating of the results was performed based on several criteria for visualization of anatomic detail of the colonic wall and mucosal surface. Except for a few cases in which insufflation of the colon was insufficient, all of the results included >95% of the colonic walls. CONCLUSION: This method for colonic wall segmentation is reliable and the segmentation results are applicable in both visualization of the colon and computer-aided diagnosis in the detection of polyps in CT colonography.

Supernumerary intrathoracic ribs: imaging features of two cases.

Intrathoracic supernumerary ribs are a rare congenital abnormality. The chest radiography and computed tomographic findings (including 3D reconstruction) of two cases are presented with a brief review of the literature.

Tumor size on computed tomography scans: is one measurement enough?

BACKGROUND: Bidimensional tumor measurements are used routinely as surrogates for tumor volume. The purpose this study was to determine whether there is any added benefit in bidimensional or tridimensional measurements over a unidimensional measurement. METHODS: Sixty-nine colorectal hepatic metastases on 19 computed tomography scans (1-8 lesions per scan) from 9 patients were analyzed. Five patients contributed 2-4 scans each (mean, 3 scans). The standard volume of these lesions was determined by the "summation of areas" technique. The maximum axial dimension, the product of the greatest axial dimensions, and several volume estimates (based on the volumes of a sphere, an ellipsoid, and a cube) each were correlated with the standard volume. RESULTS: The maximum axial dimension and the product of the greatest axial dimensions correlated equally with tumor volume (correlation coefficient = 0.93). Surrogate measures based on the equations for a sphere and an ellipsoid underestimated tumor volume, whereas the equation for a cube overestimated volume. CONCLUSIONS: When reporting tumor size, there is no significant added benefit in reporting bidimensional or tridimensional measurements over the maximum axial dimension.

Applying 'technology assessment' and 'evidence based medicine' theory to interventional radiology. Part 1: Suggestions for the phased evaluation of new procedures.

AIM: To compare and contrast interventional radiology (IR) clinical and research practices with the technology assessment and evidence-based medicine (EBM) paradigms and make suggestions for the phased evaluation of new IR procedures. MATERIALS AND METHODS: Course literature of the Association of University Radiologists' 'Basic Technology Assessment for Radiologists' course and the McMaster University Health Information Research Unit's 'How to Teach Evidence-Based Medicine 1999' course were used to identify major publications in each discipline. A computer search was performed to seek other relevant literature. A model of traditional development of IR procedures was developed. Suggestions for the phased evaluation of IR procedures were derived. RESULTS: As in diagnostic radiology, several levels of progressively stronger IR study design can be described and related to EBM 'levels of evidence'. These range from case reports and case series through case-control and cohort studies to randomized controlled trials (RCTs). The major weakness in the existing IR literature is the predominance of small, uncontrolled, case series. Randomized controlled trials are likely to provide the best possible evidence of effectiveness. They are expensive and randomization is sometimes unethical or impractical. Case-control and cohort studies have been under-utilized. Evidence-based medicine indices of benefit and harm have not yet been applied in IR and may have clinical advantages over traditional statistical methods. A literature search (10 years) using MeSH terms 'radiology, interventional' and 'efficacy' yielded 30 papers. Combining 'radiology, interventional' and 'evidence-based medicine' yielded no papers. Comparative searches substituting the term 'diagnostic imaging' for 'radiology, interventional' yielded 4883 and 62 papers, respectively. CONCLUSION: Principles of technology assessment and EBM can be applied to the investigation of new IR procedures. A tool is needed to simplify the application of EBM analytic methods. Better education in research methods is needed to raise the levels of evidence provided by the bulk of IR research and allow new procedures to be introduced into practice appropriately. Malone, D. E. & MacEneaney, P. M. (2000). Clinical Radiology55, 929-937.

Applying 'evidence-based medicine' theory to interventional radiology. Part 2: a spreadsheet for swift assessment of procedural benefit and harm.

AIM: To design a spreadsheet program to analyse interventional radiology (IR) data rapidly produced in local research or reported in the literature using 'evidence-based medicine' (EBM) parameters of treatment benefit and harm. MATERIALS AND METHODS: Microsoft Excel(TM)was used. The spreadsheet consists of three worksheets. The first shows the 'Levels of Evidence and Grades of Recommendations' that can be assigned to therapeutic studies as defined by the Oxford Centre for EBM. The second and third worksheets facilitate the EBM assessment of therapeutic benefit and harm. Validity criteria are described. These include the assessment of the adequacy of sample size in the detection of possible procedural complications. A contingency (2 x 2) table for raw data on comparative outcomes in treated patients and controls has been incorporated. Formulae for EBM calculations are related to these numerators and denominators in the spreadsheet. The parameters calculated are benefit - relative risk reduction, absolute risk reduction, number needed to treat (NNT). Harm - relative risk, relative odds, number needed to harm (NNH). Ninety-five per cent confidence intervals are calculated for all these indices. The results change automatically when the data in the therapeutic outcome cells are changed. A final section allows the user to correct the NNT or NNH in their application to individual patients. RESULTS: This spreadsheet can be used on desktop and palmtop computers. The MS Excel(TM)version can be downloaded via the Internet from the URL ftp://radiography.com/pub/TxHarm00.xls. CONCLUSION: A spreadsheet is useful for the rapid analysis of the clinical benefit and harm from IR procedures.

The role of hepatic arterial Doppler ultrasound after liver transplantation: an 'audit cycle' evaluation.

AIMS: To compare the diagnostic performance of hepatic arterial (HA) Doppler ultrasound post-liver transplantation for hepatic artery thrombosis and stenosis in our unit with the literature. To evaluate the role of the technique in clinical practice. MATERIALS AND METHODS: In a two-phase 'audit cycle' study, adult OLT patients had Doppler studies comprising detection of HA flow and measurements of peak systolic velocity, resistive index and systolic acceleration time. In phase I, patients had Doppler examinations 'routinely' and for any hepatic biochemical abnormality. In phase II, Doppler ultrasound was performed early post-OLT and later only if a senior transplant clinician suspected graft ischaemia. In addition to HA measurements the waveform was visually assessed. Clinical outcome was the 'gold standard'. RESULTS: Phase 1: 38 patients, 40 OLT operations, 125 Doppler studies; 14 arteriograms. Phase 2: 35 patients, 42 OLT operations, two HA angioplasties, one HA revision, one non-occlusive thrombus, 140 studies; 17 arteriograms. Results; Phase 1 [Phase 2]: sensitivity 80% [100%]; specificity 71% [81%]; PPV 28% [56%]; NPV 96% [100%]; incidence of HA abnormality 12.5% [19. 5%]; likelihood ratio of negative result 0.28 [0]; of positive result 2.8 [5.3]. CONCLUSION: Previously reported results are reproducible. Normal HA waveform should also be a criterion of normality. The technique is very sensitive but relatively non-specific. Predictive values improve with discriminate use. MacEneaney, P. M. (2000). Clinical Radiology55, 517-524.

Systemic to pulmonary venous shunt in superior vena cava occlusion.

This report describes systemic-to-pulmonary venous connections at the pleural level resulting from superior vena cava occlusion. The interval development of new venous collaterals within a 3-year period represents an advanced manifestation of SVC occlusion in this patient with a history of pleural disease. In this case, progressive venous thrombosis caused by underlying hypercoaguability led to the development of collaterals in unusual sites, including systemic-to-pulmonary venous shunting, and resulting in progressive cyanosis and death.

The meaning of diagnostic test results: a spreadsheet for swift data analysis.

AIMS: To design a spreadsheet program to: (a) analyse rapidly diagnostic test result data produced in local research or reported in the literature; (b) correct reported predictive values for disease prevalence in any population; (c) estimate the post-test probability of disease in individual patients. MATERIALS AND METHODS: Microsoft Excel(TM)was used. Section A: a contingency (2 x 2) table was incorporated into the spreadsheet. Formulae for standard calculations [sample size, disease prevalence, sensitivity and specificity with 95% confidence intervals, predictive values and likelihood ratios (LRs)] were linked to this table. The results change automatically when the data in the true or false negative and positive cells are changed. Section B: this estimates predictive values in any population, compensating for altered disease prevalence. Sections C-F: Bayes' theorem was incorporated to generate individual post-test probabilities. The spreadsheet generates 95% confidence intervals, LRs and a table and graph of conditional probabilities once the sensitivity and specificity of the test are entered. The latter shows the expected post-test probability of disease for any pre-test probability when a test of known sensitivity and specificity is positive or negative. RESULTS: This spreadsheet can be used on desktop and palmtop computers. The MS Excel(TM)version can be downloaded via the Internet from the URL ftp://radiography.com/pub/Rad-data99.xls CONCLUSION: A spreadsheet is useful for contingency table data analysis and assessment of the clinical meaning of diagnostic test results.