Alexander G. Pitman

Reproducibility of “Intelligent” Contouring of Gross Tumor Volume in Non-Small Cell Lung Cancer on PET/CT Images Using a Standardized Visual Method

PURPOSEnPositron emission tomography/computed tomography (PET/CT) is increasingly used for delineating gross tumor volume (GTV) in non-small-cell lung cancer (NSCLC). The methodology for contouring tumor margins remains controversial. We developed a rigorous visual protocol for contouring GTV that uses all available clinical information and studied its reproducibility in patients from a prospective PET/CT planning trial.nnnMETHODS AND MATERIALSnPlanning PET/CT scans from 6 consecutive patients were selected. Six observers (two radiation oncologists, two nuclear medicine physicians, and two radiologists) contoured GTVs for each patient using a predefined protocol and subsequently recontoured 2 patients. For the estimated GTVs and axial distances, least-squares means for each observer and for each case were calculated and compared, using the F test and pairwise t-tests. In five cases, tumor margins were also autocontoured using standardized uptake value (SUV) cutoffs of 2.5 and 3.5 and 40% SUV(max).nnnRESULTSnThe magnitude of variation between observers was small relative to the mean (coefficient of variation [CV] = 3%), and the total variation (intraclass correlation coefficient [ICC] = 3%). For estimation of superior/inferior (SI), left/right (LR), and anterior/posterior (AP) borders of the GTV, differences between observers were also small (AP, CV = 2%, ICC = 0.4%; LR, CV = 6%, ICC = 2%; SI, CV 4%, ICC = 2%). GTVs autocontoured generated using SUV 2.5, 3.5, and 40% SUV(max) differed widely in each case. An SUV contour of 2.5 was most closely correlated with the mean GTV defined by the human observers.nnnCONCLUSIONSnObserver variation contributed little to total variation in the GTV and axial distances. A visual contouring protocol gave reproducible results for contouring GTV in NSCLC.

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

Abstract. 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 (A

Reference Range for Intrapatient Variability in Blood-Pool and Liver SUV for 18F-FDG PET

774) based on a PET cost of EUR 706 (A

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

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 (A

Benign hepatic cyst mimicking a functional thyroid carcinoma metastasis on whole-body I-131 imaging.

1,252–A

The Royal Australian and New Zealand College of Radiologists (RANZCR) relative value unit workload model, its limitations and the evolution to a safety, quality and performance framework

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.

Soft tissue metastasis of carcinoid tumour: a rare manifestation

18F-FDG PET qualitative tumor response assessment or tumor-to-background ratios compare targets against blood-pool or liver activity; standardized uptake value (SUV) semiquantitation has artifacts and is validated by a stable normal-tissue baseline. The aim of this study was to document the normal intrapatient range of scan-to-scan variation in blood-pool SUV and liver SUV and to identify factors that may adversely affect it (increase its spread). Methods: Between July 2009 and June 2010, 132 oncology patients had 2 PET/CT scans. Patient preparation, acquisition, and reconstruction protocols were held stable, uniform, and reproducible. Mean SUV (body weight) values were obtained from 2-dimensional regions of interest in the aortic arch blood pool and in the right lobe of the liver. Results: Of the 132 patients, 65 had lymphoma. Their mean age was 62.5 y. The group’s mean serum glucose level was 6.0 mmol/L at the first visit and 5.9 mmol/L at the second visit. The mean 18F-FDG dose was 4.1 MBq/kg at the first visit and 4.0 at the second. At the first visit, the group’s mean blood-pool SUV was 1.55 (SD, 0.38); at the second, 1.58 (SD, 0.37)—not statistically different. The group’s mean liver SUV was 2.17 (SD, 0.44) at the first visit and 2.29 (SD, 0.44) at the second (P = 0.005). Visit-to-visit intrapatient variation in blood-pool and liver SUVs had gaussian distributions. The variation in blood-pool SUV had a mean of 0.03 and SD of 0.42. The variation in liver SUV had a mean of 0.12 and SD of 0.50. Using 95th percentiles, the reference range in our patient population for intrapatient variation was −0.8 to 0.9 for blood pool SUV and −0.9 to 1.1 for liver SUV. Subanalysis by cancer type and chemotherapy suggested that the rise in liver SUV between the 2 visits was largely due to the commencement of chemotherapy, but no factors were identified as systematically affecting intrapatient variation, and no factors were identified as increasing its spread. Conclusion: In our patient cohort, the reference range for intrapatient variation in blood-pool and liver SUVs is −0.8 to 0.9 and −0.9 to 1.1, respectively.

Comparison of 3MP medical-grade to 1MP office-grade LCD monitors in mammographic diagnostic and perceptual performance

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 (Pu2003>u20030.05). 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.

Magnetic resonance colonography for colorectal cancer screening in patients with Lynch syndrome gene mutation

A 56-year-old woman received an ablative dose of I-131 after total thyroidectomy for a 15-mm follicular carcinoma. Gamma camera imaging performed 10 days later revealed a focus of liver uptake suggestive of a solitary, functional metastasis. Subsequent computed tomographic (CT) images showed a benign hepatic cyst at the site of uptake. Cysts in other organs such as breast and kidney have been reported as causes of false-positive I-131 scans, but this is the first reported case of uptake by a benign hepatic cyst.

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

The study reports on the evolution of the Australian radiologist relative value unit (RVU) model of measuring radiologist reporting workloads in teaching hospital departments, and aims to outline a way forward for the development of a broad national safety, quality and performance framework that enables value mapping, measurement and benchmarking. The Radiology International Benchmarking Project of Queensland Health provided a suitable high‐level national forum where the existing Pitman–Jones RVU model was applied to contemporaneous data, and its shortcomings and potential avenues for future development were analysed. Application of the Pitman–Jones model to Queensland data and also a Victorian benchmark showed that the original recommendation of 40u2003000 crude RVU per full‐time equivalent consultant radiologist (97–98 baseline level) has risen only moderately, to now lie around 45u2003000 crude RVU/full‐time equivalent. Notwithstanding this, the model has a number of weaknesses and is becoming outdated, as it cannot capture newer time‐consuming examinations particularly in CT. A significant re‐evaluation of the value of medical imaging is required, and is now occurring. We must rethink how we measure, benchmark, display and continually improve medical imaging safety, quality and performance, throughout the imaging care cycle and beyond. It will be necessary to ensure alignment with patient needs, as well as clinical and organisational objectives. Clear recommendations for the development of an updated national reporting workload RVU system are available, and an opportunity now exists for developing a much broader national model. A more sophisticated and balanced multidimensional safety, quality and performance framework that enables measurement and benchmarking of all important elements of health‐care service is needed.