Partial-volume effect correction in positron emission tomography brain scan image using super-resolution image reconstruction.

OBJECTIVE: The partial-volume effect (PVE) is a consequence of limited (i.e. finite) spatial resolution. PVE can lead to quantitative underestimation of activity concentrations in reconstructed images, which may result in misinterpretation of positron emission tomography (PET) scan images, especially in the brain. The PVE becomes significant when the dimensions of a source region are less than two to three times the full width at half maximum spatial resolution of the imaging system. In the present study, the ability of super-resolution (SR) image reconstruction to compensate for PVE in PET was characterized. METHODS: The ability of SR image reconstruction technique to recover activity concentrations in small structures was evaluated by comparing images before and after image reconstruction in the NEMA/IEC phantom (Washington, DC), in the Hoffman brain phantom and in four human brain subjects (three normal subjects and one atrophic brain subject) in terms of apparent recovery coefficient (ARC) and percentage yield. RESULTS: Both the ARC and percentage yield are improved after SR implementation in NEMA/IEC phantom and Hoffman brain phantom. When tested in normal subjects, SR implementation can improve the intensity and justify SR efficiency to correct PVE. CONCLUSION: SR algorithm can be used to effectively correct PVE in PET images. ADVANCES IN KNOWLEDGE: The current research focused on brain PET scanning exclusively; future work will extend to whole-body imaging.

Value of Osteoporosis Self-assessment Tools for Asians (OSTA) with or without Brown's clinical risk factors in detection of postmenopausal osteoporosis.

OBJECTIVE: To evaluate the value of Osteoporosis Self-assessment Tools for Asians (OSTA) score, Brown's clinical risk assessment and their combination as screening tools for postmenopausal osteoporosis. METHODS: Two hundred postmenopausal women were enrolled between August 2010 and January 2011. The weight and age of all participants were collected for the OSTA score. Clinical risk factors were collected for Brown's criteria. Bone mineral density was measured using dual-energy X-ray absorptiometry. RESULTS: The mean age (± standard deviation (range)) of the studied population was 60.1 ± 7.8 (41-81) years. Twenty-one percent of the participants had either osteoporosis of the lumbar spine, or femoral neck or both, of which 8% had osteoporosis at the lumbar spine and 17% had osteoporosis at the femoral neck. The sensitivity and specificity for OSTA score cut-off values of ≤ -1 were 78.6% and 58.2% and for Brown's clinical risk factors were 57.1% and 71.5%, respectively. When the OSTA score of ≤ -1 and Brown's clinical risk factors were combined to screen participants with positive values for one or both test(s), the sensitivity increased from 78.6% to 81.0%, while the specificity decreased from 58.2% to 50.6%. The positive predictive values of the OSTA score, Brown's clinical criteria and the combined tools ranged between 30.4 and 70.6%. CONCLUSIONS: An OSTA score of ≤ -1 seems to have higher sensitivity compared to Brown's clinical risk factor assessment. The combination of both tools provides a slight improvement in sensitivity but with a decline in specificity.

Detection of acute cerebral ischaemia with Tc-99m apcitide scintigraphy.

The established indication for Tc99m apcitide scintigraphy is for detecting deep venous thrombosis. However, due to its mechanism of binding to GP IIb/IIIa receptors on activated platelets, it can be used to image acute cerebral thrombosis. I report a patient with an acute ischaemic stroke, with right leg swelling, referred for Tc99m apcitide scintigraphy to show of deep venous thrombosis. There was no abnormal uptake in the legs but there was in the left parieto-occipital region. This correlated with the clinical and CT data, indicating an acute ischaemic stroke in this area.

Detection of restenosis after percutaneous transluminal coronary angioplasty using the exercise treadmill test and technetium 99m-sestamibi scintigraphy.

BACKGROUND: The detection of myocardial ischemia after percutaneous transluminal coronary angioplasty (PTCA) is important because 30-50 per cent of the patients will develop restenosis within 6 months. Symptoms of chest pain and exercise stress test (EST) have shown to be less sensitive for detection of ischemia than exercise Technetium-99m Sestamibi (Tc-99m MIBI). The purpose of this study was to compare the sensitivity and specificity of chest pain, EST and Tc-99m MIBI with coronary angiography (CAG). METHOD: Tc-99m MIBI with SPECT imaging was performed at months 1, 3 and 6 and CAG was repeated 6 months after successful PTCA. Earlier Tc-99m MIBI and CAG were performed in patients with recurrent angina pectoris or suspected restenosis. RESULTS: Forty six patients (M 29, F 17) who had undergone successful angioplasty were prospectively enrolled. Their mean age was 61 +/- 19 yrs. Eighty eight lesions (LAD63%, LCX34%, RCA19%) were performed. Lesion characteristics were type A in 9 per cent, type in B 30 per cent and type C in 61 per cent. Fifty four per cent of PTCA were performed for single vessel disease and 46 per cent for multivessel disease. The mean duration of time between PTCA and follow-up CAG was 6.1 +/- 2.7 months. We detected restenosis from CAG in 58 per cent of the cases. The Tc-99m MIBI had higher sensitivity to detect restenosis than anginal pain (85.0% vs 39.4% p < 0.005) or EST (85.0% vs 63.6% p < 0.05) when compared with CAG. The overall accuracy of Tc-99m MIBI for the detection of restenosis was 80 per cent. CONCLUSION: Tc-99m MIBI with SPECT imaging constitutes a better means than symptoms or exercise test to detect restenosis after successful coronary angioplasty.

131I MIBG therapy in neuroblastoma: mechanisms, rationale, and current status.

131I MIBG has been used as palliative treatment of neuroblastoma patients with recurrent or persistent disease who failed other modalities of treatment. Since the results were promising, the concept arose of using it in conjunction with other modalities, either as an up-front treatment or as combination therapy. This article reviews the principle of 131I MIBG treatment, in conjunction with other modalities currently used for the treatment of neuroblastoma, in an attempt to improve the final outcome.