Diagnostic accuracy of mammography readers and their memory performance have no correlation with each other.

INTRODUCTION: The study aims to determine if any association exists between visual memory performance and diagnostic accuracy performance in a group of radiologist mammogram readers. MATERIALS AND METHODS: One hundred proven mammograms (23 with cancers) were grouped into 5 sets of 20 cases, with sets being of equal difficulty. Pairs of sets were presented in 5 reads (40 cases per read, order random) to a panel of 8 radiologist readers (either present or past screening readers, with experience range from <1 year to >20 years). The readers were asked to either 'clear' or 'call back' cases depending on need for further workup, and at post-baseline reads to indicate whether each case was 'new' or 'old' (i.e. remembered from prior read). Two sets were presented only at baseline (40 cases per reader), and were used to calculate the reader's false recollection rate. Three sets were repeated post-baseline once or twice (100 cases per reader). Reading conditions were standardised. RESULTS: Memory performance differed markedly between readers. The number of correctly remembered cases (of 100 'old' cases) had a median of 10.5 and range of 0-58. The observed number of false recollections (of 40 'totally new' cases) had a median of 2 and range of 0-17. Diagnostic performance measures were mean (range): sensitivity 0.68 (0.54-0.81); specificity 0.82 (0.74-0.91); positive predictive value (PPV) 0.55 (0.50-0.65); negative predictive value (NPV) 0.89 (0.86-0.93) and accuracy 0.78 (0.76-0.83). Confidence intervals (CIs; 95%) for each reader overlapped for all the diagnostic parameters, indicating a lack of statistically significant difference between the readers at the 5% level. The most sensitive and the most specific reader showed a trend away from each other on sensitivity, specificity, NPV and PPV; their accuracies were 0.76 and 0.82, respectively, and their accuracy 95% CIs overlapped considerably. Correlation analysis by reader showed no association between observed memory performance and any of the diagnostic accuracy measures in our group of readers. In particular, there was no correlation between diagnostic accuracy and memory performance. CONCLUSION: There was no association between visual memory performance and diagnostic accuracy as a screening mammographer in our group of eight representative readers. Whether a radiologist has a good or a bad visual memory for cases, and in particular mammograms, should not impact on his or her performance as a radiologist and mammogram reader.

The four horsemen: clinicopathological correlation in 407 hospital autopsies.

BACKGROUND: Few previous papers comparing clinical diagnoses with autopsy findings present sensitivities and positive predictive values for individual conditions. The aim of this study is to determine the sensitivity and positive predictive value of current clinical diagnosis both overall and for individual conditions. METHODS: Retrospective review of hospital records of a consecutive series of patients undergoing hospital autopsy at two metropolitan teaching hospitals over a 7-year period (407 patients). Comparison was made with autopsy reports to allocate one of three outcome measures (true-positive, false-positive, false-negative) to each condition. RESULTS: The overall sensitivity and positive predictive value of clinical diagnosis were 0.74 and 0.93 respectively. Pneumonia, acute myocardial infarction, bowel ischaemia and pulmonary embolism were each present in greater than 10% of patients and had sensitivities below 0.70 and positive predictive values below 0.90. CONCLUSION: There exists a large burden of clinically undiagnosed and incorrectly diagnosed disease in hospital. Pneumonia, acute myocardial infarction, bowel ischaemia and pulmonary embolism represent important and difficult diagnostic challenges.

Circle of Willis artery diameters on MR angiography: an Australian reference database.

The aim was to establish a reference range of measurements for all major Circle of Willis (COW) arteries for an Australian population of patients presenting for brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) that is typical of a tertiary referral hospital; and to report the prevalence and disease associations of COW variants in our patient population. All technically diagnostic MRI and MRA studies performed at our magnetic resonance (MR) centre in the calendar year 2006 were re-read by one reader who classified the COW anatomical layout and measured diameters of all the major vessels at defined locations. A subset of 30 was independently re-read by another reader and the interobserver measurement variability analyzed. Graphical analysis, with 95% confidence intervals (95CI), summary statistics reporting, t-testing for unpaired and for paired means, Hauck-Anderson (H-A) clinical equivalence testing and logistic regression analysis for categorical variables was performed as relevant. One hundred and seventy-one studies (of 187 eligible) formed the analysis population. All of our patients had vessels of comparable calibre regardless of MRI disease status, gender or COW variant (P > 0.05). Basilar artery (BA) diameter showed significant association with age, but other vessel diameters did not. The reference range is widely applicable, methodology straightforward and appears tolerant of interobserver variability. A number of discontinuous COW variants become more prevalent with age, perhaps from atherosclerotic occlusive disease. There was no association between COW variants, gender, aneurysm location or MRI disease status.

Diagnostic errors in patients dying in hospital: radiology's contribution.

We propose a comprehensive taxonomy of diagnostic errors in radiology that incorporates requests, image acquisition, radiological reports and evidence of communication to the treating team, and is retrospectively applicable to a given set of radiological episodes using pre-existing standard hospital databases. The taxonomy applies four binary tests to each diagnostic error using widely available hospital records, such as radiological requests, images in Picture Archiving and Communication System, radiological reports and hospital patient records. The taxonomy classifies errors into seven mutually exclusive patterns: no relevant imaging, consistent error (technical non-demonstration), consistent error (human error), ignored correct dissenting radiology result, de novo radiology error (technical non-demonstration), de novo radiology error (human error), and ignored correct confirmatory radiology result. The taxonomy was validated against a set of 250 diagnostic errors identified from an audit of clinical and radiological diagnoses with autopsy as the reference standard. All errors were successfully classified by the taxonomy, and the point of initiation of the error assigned. Of a total of 250 diagnostic errors, 138 (55%) had no relevant imaging performed. Ninety percent of all errors (226) were due to human error only, whether at the stage of clinical suspicion, the radiologist's diagnosis, or afterwards. Of the 112 imaged errors, only 12 (11%) were initiated at diagnostic imaging. The taxonomy of diagnostic error we present is comprehensive, allows retrospective audit of error with commonly available data, and provides clinically useful identification of the point of error initiation.

Resuscitation skills for radiologists: a short paper.

The radiologist is likely to be the first medical practitioner on the scene for contrast reactions, anaphylaxis and other common medical emergencies that occur in radiology departments and stand-alone practices. Until 2007, the Royal Australian and New Zealand College of Radiologists (RANZCR) did not provide resuscitation training as a CPD service for fellows, and the need for such a service has not been gauged. In 2007, the authors ran the first RANZCR large-group resuscitation refresher training workshop at the Melbourne 2007 annual scientific meeting. The workshop maximized audience participation and knowledge transfer in a constrained time, disseminated guidelines, and collected feedback on the need for further resuscitation training for radiologists. Of the 100 feedback forms, 82 were returned. All the 82 responses wanted the workshop repeated at future annual scientific meetings, and 71 wanted RANZCR to provide hands-on refresher training. Sixty-six responders indicated when they had their most recent resuscitation training: six in the past 12 months, 25 in the past 3 years and 35 longer than 3 years. Sixty-nine responded on availability of resuscitation training at their workplace: 33 indicated 'Yes' and 36 'No'. There is a definite need to provide resuscitation training for radiologists in Australia. At the end of this article, we reproduce the currently applicable guidelines as a service to our readers.

Editorial experience with 1 year of case reports: a case report and review of the literature.

UNLABELLED: We analysed the properties of radiology case reports to create a 'personality profile'. METHODS: In total, 99 case reports accepted for publication over 1 year were classified on a number of categorical parameters. RESULTS: The commonest reported underlying aetiology was tumour (n=40), and the commonest radiological presentation was with a mass (n=29). Classic presentations of rare conditions (33%) were as common as rare presentations of common conditions (35%). Most underlying pathologies were proven with histology. Ten reports were interventional. CONCLUSION: The typical case report is of a tumour presenting as a mass, and ultimately proven by histology.

Isolated limb infusion for local control of lower limb melanoma: radiologic aspects.

To describe the technical radiological aspects of isolated limb infusion (ILI) to assist those procedural radiologists who carry out ILI on an occasional only basis and to inform the Australian radiologist community about this deserving but relatively little known radiological procedure. Retrospective audit of radiological catheter placement for 23 lower limb ILI procedures carried out for 16 patients with locally recurrent melanoma over 2 years (January 2002 to December 2003). Arterial and venous catheter placement, although sometimes difficult, was successful in all but four occasions. Unfavourable vascular anatomy was the main reason for failure. If approached systematically and with the knowledge of the patient's vascular anatomy, the outcome will be satisfactory in the hands of the generalist. Knowing the common technical pitfalls will certainly assist. Isolated limb infusion deserves to be more widely known in the radiological and surgical communities.

Perceptual error and the culture of open disclosure in Australian radiology.

The work of diagnostic radiology consists of the complete detection of all abnormalities in an imaging examination and their accurate diagnosis. Errors in diagnostic radiology comprise perceptual errors, which are a failure of detection, and interpretation errors, which are errors of diagnosis. Perceptual errors are subject to rules of human perception and can be expected in a proportion of observations by any human observer including a trained professional under ideal conditions. Current legal standards of medical negligence make no allowance for perceptual errors, comparing human performance to an ideal standard. Diagnostic radiology in Australia has a culture of open disclosure, where full unbiased evidence from an examination is provided to the patient together with the report. This practice benefits the public by allowing genuine differences of opinion and also by allowing a second chance of correct diagnosis in cases of perceptual error. The culture of open disclosure, which is unique to diagnostic radiology, places radiologists at distinct medicolegal disadvantage compared with other specialties. (i) Perceptual error should be acknowledged as an integral inevitable part of diagnostic radiology; (ii) culture of open disclosure should be encouraged by the profession; and (iii) a pragmatic definition of medical negligence should reflect the imperfect performance of human observers.

Radiologist workloads in teaching hospital departments: measuring the workload.

This article proposes a practical method for measuring staff radiologist workloads (clinical productivity) in teaching hospital departments of radiology in Australia. It reviews the Australian background to this, including the Royal Australian and New Zealand College of Radiologists (RANZCR) Education Board accreditation guidelines and the development of the RANZCR practice costing model. It reviews overseas methods of radiologist workload measurement and trends in radiologist workloads both in Australia and overseas. It proposes a practical and simple workload measuring method based on relative value units derived from the RANZCR model. Using a previous national workload survey in teaching hospitals, it proposes initial workload benchmarks when using this method. Strengths and weaknesses of this method and alternatives are reviewed, and a number of proposals for Australian teaching radiology departments are put forward to advance the issue of radiologist workloads in a disciplined manner.

Reversible posterior leukoencephalopathy syndrome complicating cytotoxic chemotherapy for hematologic malignancies.

Reversible posterior leukoencephalopathy syndrome (RPLS) is an uncommon but distinctive clinicoradiological entity comprising of headache, seizures, visual disturbance, and altered mental function, in association with posterior cerebral white matter edema. With appropriate management, RPLS is reversible in the majority of cases. Previous reported associations of RPLS include hypertension, eclampsia, renal failure, and use of immunosuppressive drugs; reports in the adult hematology setting are rare. We report two cases of adults undergoing treatment for hematological malignancies who developed RPLS, and we emphasize the importance of early recognition and institution of appropriate management in reducing the risk of development of permanent neurological disability.

Fluoroscopically guided percutaneous radiological gastrostomy: technique, methodology and pitfalls.

Fluoroscopically guided percutaneous gastrostomy tube placement is an uncommon but well-established interventional procedure. We present our experience of this procedure in a series of 23 patients, concentrating on the methodology, technique and pitfalls.

Solitary pulmonary nodules: accuracy and cost-effectiveness of sodium iodide FDG-PET using Australian data.

This study uses Australian data to confirm the accuracy of dedicated sodium iodide (NaI) fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in evaluating indeterminate solitary pulmonary nodules (SPNs) and to determine the conditions under which PET could play a cost-effective role in this evaluation. Ninety-two patients from two Australian hospitals in different states underwent FDG-PET for evaluation of an SPN. Observed values for prior probability of malignancy and diagnostic accuracy of PET were applied to previously published decision tree models using published Australian health care costs. The accuracy of FDG-PET was 93% with a sensitivity of 92% and a specificity of 95%. The prior probability of malignancy (0.54), PET sensitivity and PET specificity indicated cost savings per patient of up to EUR 455 (Adollars 774) based on a PET cost of EUR 706 (Adollars 1,200). PET would remain cost-effective for levels of prior probability up to 0.8-0.9 and a PET cost of EUR 736-1,161 (Adollars 1,252-Adollars 1,974). It is concluded that NaI PET is accurate, cost saving and cost-effective for the characterisation of indeterminate pulmonary nodules in Australia. Comparison with previous reports from the United States confirms that FDG-PET can remain cost-effective despite population differences in medical costs, disease prevalence and PET diagnostic performance.

Performance of sodium iodide based (18)F-fluorodeoxyglucose positron emission tomography in the characterization of indeterminate pulmonary nodules or masses.

The purpose of this study was to document the accuracy of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) with sodium iodide detectors in characterizing indeterminate lung nodules or masses and in identifying additional extra-lesional findings. 50 consecutive patients without a confident diagnosis of malignancy on CT underwent (18)FDG PET with and without attenuation correction. The diagnosis of malignancy was made using visual diagnostic criteria, and tumour-to-blood pool ratios were calculated. The final diagnosis was established by surgery, biopsy or long-term follow-up. Any additional findings made at PET were recorded and similarly verified. Using blinded visual diagnostic criteria for the differentiation of malignant from benign nodules, sodium iodide PET achieved a sensitivity of 91% (30 of 33 cases), a specificity of 88% (15 of 17 cases), a positive predictive value for malignancy of 94% (30 of 32 cases) and a negative predictive value of 83% (15 of 18 cases). False positives occurred with active tuberculosis and sarcoidosis. False negatives were a 3 cm bronchoalveolar carcinoma, a 1.3 cm sarcoma metastasis and a 1 cm carcinoma. Use of tumour-to-blood pool ratios did not improve performance. PET suggested the presence of nodal or distant metastases in 13 of 33 patients with a malignant pulmonary lesion. These PET findings were confirmed in 11 patients. These results indicate that sodium iodide PET is an accurate tool for the characterization of indeterminate pulmonary masses or nodules and simultaneously provides non-invasive staging information that can alter patient management in up to one-third of such patients. Performance of sodium iodide PET is comparable with reported results for PET scanners using other detector materials.

Positron emission tomography in pulmonary masses where tissue diagnosis is unhelpful or not possible.

OBJECTIVE: To document the usefulness of positron emission tomography (PET) in diagnosing lung masses where tissue diagnosis is not possible or is unhelpful. DESIGN: Cohort study (partly retrospective). SETTING: Departments of positron emission tomography and diagnostic imaging of a tertiary referral dedicated cancer hospital in Melbourne. PATIENTS: 40 of 60 consecutive patients referred for evaluation of an indeterminate lung nodule or mass, comprising 15 in whom biopsy was not possible and 25 in whom biopsy had either failed or did not confirm malignancy or a specific benign diagnosis. MAIN OUTCOME MEASURES: Accuracy of blinded reading of PET scans in determining whether the lung lesion is benign or malignant (final diagnosis established either through surgical biopsy or from long term clinical and imaging follow-up). RESULTS: PET yielded 23 true positives, 13 true negatives, 3 false positives (2 tuberculosis, 1 sarcoidosis) and 1 false negative (an adenocarcinoma), giving a sensitivity of 96%, a specificity of 81%, a negative predictive value of 93%, and a positive predictive value of 88% (for malignancy). CONCLUSIONS: For lung nodules where tissue diagnosis was not possible or was unhelpful, the negative predictive power of PET was sufficiently high to avoid open biopsy, and to follow such patients with serial surveillance. On the other hand, most lesions that were positive on PET were either malignant or required specific active management determined from histological characterisation. PET therefore contributed to improved patient management and has reduced the need for open thoracotomy.

Cardiac blood-pool imaging in oncology more than an ejection fraction?

Cardiac function is commonly evaluated in patients with cancer in most nuclear medicine departments. At their dedicated cancer facility, the authors routinely perform a dynamic right anterior oblique first-pass study and a 4-minute left anterior oblique static planar study in addition to the routine equilibrium gated scanning in appropriate projections. Here they show the range of noncardiac disease encountered using this protocol. Useful unexpected information can be obtained from left ventricular ejection studies, and further data may be gained from these simple additions to this common test.

Intravenous extension of lung carcinoma to the left atrium: demonstration by positron emission tomography with CT correlation.

Intravenous extension of lung carcinoma is rare. A right upper lobe bronchogenic carcinoma with unusually elongated intravenous extension to the left atrium was first visualized with positron emission tomography (PET) and then confirmed with dynamic CT. The PET appearance of intravascular tumour spread is striking, and presents only a short differential diagnosis.

Stereoscopic presentation of computed tomography and magnetic resonance images.

This technical note describes a direct and simple method of stereoscopically presenting three-dimensional (3-D) CT and MRI volumetric models. This method has negligible cost both in monetary terms and in extra processing time, is extremely accessible, easy to learn and apply and can be effectively used in the absence of any sophisticated equipment. It has the potential to greatly boost the communications value of many complex studies where 3-D models are already normally generated.

Radiation dose in computed tomography of the pelvis: comparison of helical and axial scanning.

An anthropomorphic Rando phantom was used to compare radiation doses sustained during helical and conventional axial CT of the pelvis. The values obtained with the Rando phantom were validated against cadaveric phantoms, and show good agreement. For the authors' particular CT unit, helical scanning was found to deliver a lower radiation dose than conventional axial scanning. This was most prominent at 1.0-s tube rotation times (average dose ratio 1.24). For realistic scanning parameters and exposure factors, the ratio of radiation dose to pelvic organs can be expected to lie in the range of 40-100 mGy. The whole-body effective dose (ED) depends on selection of scanning parameters and patients anatomy. In a favourable case scenario, the ED for CT scanning of the pelvis in a male can be expected to be between 10 and 20 mSv if the scrotum is not included in the radiation field, while the ED in a female will be approximately 20 mSv. An examination of scatter radiation fall-off curves from a single slice shows that the spread of scatter radiation is only marginally affected by slice thickness. A total of 10-12 cm of human soft tissue acts as a good barrier against internal scattered radiation. The use of such scatter fall-off curves, together with manufacturers' dosimetry specifications, allows a fast estimate of absorbed dose.