Computer-aided diagnosis for (123I)FP-CIT imaging: impact on clinical reporting.

BACKGROUND: For (123I)FP-CIT imaging, a number of algorithms have shown high performance in distinguishing normal patient images from those with disease, but none have yet been tested as part of reporting workflows. This study aims to evaluate the impact on reporters' performance of a computer-aided diagnosis (CADx) tool developed from established machine learning technology. Three experienced (123I)FP-CIT reporters (two radiologists and one clinical scientist) were asked to visually score 155 reconstructed clinical and research images on a 5-point diagnostic confidence scale (read 1). Once completed, the process was then repeated (read 2). Immediately after submitting each image score for a second time, the CADx system output was displayed to reporters alongside the image data. With this information available, the reporters submitted a score for the third time (read 3). Comparisons between reads 1 and 2 provided evidence of intra-operator reliability, and differences between reads 2 and 3 showed the impact of the CADx. RESULTS: The performance of all reporters demonstrated a degree of variability when analysing images through visual analysis alone. However, inclusion of CADx improved consistency between reporters, for both clinical and research data. The introduction of CADx increased the accuracy of the radiologists when reporting (unfamiliar) research images but had less impact on the clinical scientist and caused no significant change in accuracy for the clinical data. CONCLUSIONS: The outcomes for this study indicate the value of CADx as a diagnostic aid in the clinic and encourage future development for more refined incorporation into clinical practice.

Half-body single photon emission computed tomography with resolution recovery for the evaluation of metastatic bone disease: implementation into routine clinical service.

OBJECTIVES: Typically, scintigraphic evaluation of metastatic bone disease uses planar imaging. Although single photon emission computed tomography (SPECT) offers increased clinical utility, the acquisition time necessary to cover the required scan range (at our centre, skull vertex to mid-femur) has made its use in place of planar imaging impracticable. Recently, reconstruction with resolution recovery (RR) has allowed SPECT acquisition times to be shortened while maintaining acceptable image quality. This study was carried out to establish whether half-body SPECT with RR could replace planar scintigraphy in routine practice. METHODS: A series of reduced acquisition time SPECT scans were reconstructed retrospectively and reviewed to establish optimal reconstruction parameters. Twenty patients referred for evaluation of bone metastases underwent planar imaging, followed by half-body SPECT, reconstructed using the optimized parameters. SPECT and planar images were reported by an experienced radiologist, who reviewed image quality and recorded the number of lesions observed, their location, clinical significance and reporter confidence. RESULTS: SPECT images of acceptable quality and covering the range from skull vertex to mid-femur were acquired in 33 min. Audit indicated that SPECT identified clinically significant lesions not reported from planar views and improved lesion localization and reporter confidence. CONCLUSION: Reduced acquisition times together with RR allowed half-body SPECT for the evaluation of bone metastases to be accommodated within our department's schedule. Audit indicated that SPECT delivered the expected clinical advantages. Half-body SPECT has replaced planar imaging for the routine evaluation of metastatic bone disease at our centre, with ∼2500 studies carried out to date.

Thyroid incidentalomas on PET imaging--evaluation of management and clinical outcomes.

OBJECTIVES: 1. To determine the incidence of 'thyroid incidentaloma' in patients undergoing PET/CT in Sheffield. 2. To assess the distribution of cancer type, stage and short term outcomes of incidentally detected thyroid cancer in this cohort. METHODOLOGY: Patients with an unexpected thyroid radio-isotope uptake on reports of whole body nuclear imaging performed in Sheffield Teaching Hospitals NHS Foundation Trust for 'non-thyroid' indications from April 2008 to March 2011 were identified. Patients who have undergone PET imaging were then selected. The management, clinical and pathology details and short term 'thyroid-related' outcomes of patients with thyroid incidentaloma on PET scans were analysed. RESULTS: 1730 PET nuclear imaging studies were performed in this period. Thyroid incidentalomas were detected in 65 (3.8%)of these scans. Two thyroid cancers were detected in this cohort, both demonstrated focal uptake on the PET scan. Histology showed papillary thyroid cancer (TNM classification; pT1N1Mx and pT1bNxMx). CONCLUSION: The risk of cancer in PET detected thyroid incidentaloma in this series (3%) is low compared to published literature (5-50%). Potential reasons are discussed. The low rate of thyroid cancer in our incidentaloma cohort will influence decision making regarding management of these lesions. Only two thyroid cancers were detected in our cohort, limiting the narrative on type, stage of PET detected thyroid cancer and outcomes. Further observational research is required to study the natural history of these lesions in settings where there is a clear protocol for imaging, biopsy and treatment.

3D contrast-enhanced lung perfusion MRI is an effective screening tool for chronic thromboembolic pulmonary hypertension: results from the ASPIRE Registry.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a complication of pulmonary embolism potentially curable by surgery. Perfusion scintigraphy is currently advocated as the imaging modality of choice to exclude CTEPH due to its high sensitivity. We have evaluated the diagnostic utility of lung perfusion MRI. METHODS: Consecutive patients attending a pulmonary hypertension referral centre undergoing lung perfusion MRI, perfusion scintigraphy, CT pulmonary angiography (CTPA) and right heart catheterisation within 14 days were identified. RESULTS: Of 132 patients, 78 were diagnosed as having CTEPH. Lung perfusion MRI correctly identified 76 patients as having CTEPH with an overall sensitivity of 97%, specificity 92%, positive predictive value 95% and negative predictive value 96% compared with perfusion scintigraphy (sensitivity 96%, specificity 90%) and CTPA (sensitivity 94%, specificity 98%). No cases of surgically accessible CTEPH were missed with either modality. CONCLUSIONS: Lung perfusion MRI has high sensitivity equivalent to perfusion scintigraphy in diagnosing CTEPH but does not require ionising radiation, making it an attractive initial imaging modality to assess patients with suspected CTEPH.

99mTc white-cell imaging in inflammatory bowel disease: a comparison of planar versus SPECT.

OBJECTIVE: 99mTc-labelled white-cell scintigraphy is sensitive and specific for detecting inflammatory bowel disease (IBD). A retrospective analysis was carried out on 99 consecutive studies to compare results from planar imaging and single photon emission computed tomography (SPECT). MATERIALS AND METHODS: Two observers blindly and independently reported all planar images followed by the SPECTs. Both sets of scans were reported in random order. All possible abnormalities were assigned a confidence rating and specific, preagreed bowel location and their extent measured. RESULTS: The observers disagreed on whether studies were normal in 17 of 99 planar scans (κ=0.56) but only eight of 99 SPECTs (κ=0.83). Consensus reporting, where there was disagreement between observers, yielded the following results: planar and SPECT normal in 56 of 99 cases; planar and SPECT positive in 29 of 99 cases; planar normal but SPECT positive in 13 of 99 cases; planar positive but SPECT normal in one of 99 cases. In the 14 of 99 cases where there was discordance between planar and SPECT, confirmation of active IBD was sought from other investigations (e.g. histology). Relevant other investigations were available in eight of these discordant cases and showed agreement with the SPECT result in seven of eight patients. Where the same abnormalities were identified in both planar and SPECT, there was a significant increase (P<0.001 mean: 57 mm) in the extent of abnormalities as measured from SPECT compared with planar. CONCLUSION: Reporting from SPECT improves inter-operator variability and appears to improve sensitivity for detecting IBD. Planar imaging also appears to underestimate the extent of active disease.

Gastric sarcoidosis mimicking irritable bowel syndrome--cause not association?

Sarcoidosis is a systemic disease of unknown aetiology that may affect any organ in the body. The gastrointestinal tract however is only rarely affected outside the liver. Symptoms may be non-specific. Irritable bowel syndrome (IBS) is a common diagnosis. The recognition of IBS is aided by the use of the Rome II criteria - in the absence of organic disease. We describe the first case of a patient with gastric sarcoidosis who presented with IBS symptoms but subsequently responded to immunosuppressive therapy.