Discrepancies between positron emission tomography/magnetic resonance imaging and positron emission tomography/computed tomography in a cohort of oncological patients.

INTRODUCTION: This study aims to evaluate discrepant findings between positron emission tomography/magnetic resonance imaging (PET/MRI) and positron emission tomography/computed tomography (PET/CT) in a cohort of oncological patients and to undertake a phantom study to assess the potential for extended PET acquisitions to lead to false-positive findings on PET/MRI. METHODS: Discrepant findings from a series of 106 patients undergoing same-day 18 F-fluorodeoxyglucose (FDG)-PET/CT and PET/MRI were reviewed. Phantom studies explored the potential for PET acquisition time to contribute to discrepancy. RESULTS: There were 14 discrepant cases, 5 (35.7%) of which related to PET/MRI acquisitions that had been extended to 10 min. Three of these five cases proved to be falsely positive. Phantom studies showed greater contrast recovery and signal to noise ratio for 10-min PET/MRI acquisitions compared to 2-min acquisitions using PET/CT. There were no discrepancies when PET/CT showed disseminated disease (P = 0.036). CONCLUSIONS: Extended PET/MRI acquisitions used to accommodate multiple MRI sequences may be associated with false-positive findings compared to PET/CT. PET/MRI is more likely to have incremental value when the prior probability for disseminated disease is low.

Concordance of 18F-FDG PET Uptake in Tumor and Normal Tissues on PET/MRI and PET/CT.

AIM: The aim of this study was to assess the concordance of PET measurements of F-FDG uptake in tumor and normal tissues obtained on Australia's first clinical PET/MRI scanner in comparison to PET/CT, with comparison against published data. METHODS: One hundred subjects were prospectively recruited from an unselected, heterogeneous group of cancer patients to undergo F-FDG PET/CT and PET/MRI on the same day. SUVs of physiological regions and tumor tissues obtained by PET/MRI and PET/CT were compared and benchmarked against existing published data. Physiological activity was measured in the thoracic aorta and right lobe of the liver. Tumor SUVs were analyzed by cancer type, body region, and a combined group of all lesions. RESULTS: There was an excellent correlation between SUV measurements in tumor lesions obtained by PET/MRI and PET/CT, across all body regions and in all tumor types studied. There was a less robust correlation for SUVs measured in areas of physiological activity, but the level of agreement still fell within 2 SDs of mean. Data from this study showed comparable or smaller systemic biases and narrower confidence limits than existing studies in the literature comparing SUVs from PET/MRI and PET/CT. CONCLUSIONS: F-FDG PET/MRI appears promising as an adjunct or alternative to PET/CT for quantitative evaluation in oncology, independent of body region and tumor type, across a wide range of SUVs.

Infrared thermography in the detection of brown adipose tissue in humans.

PET-CT using (18)F-FDG is employed for detecting brown adipose tissue (BAT) in humans. Alternative methods are needed because of the radiation and cost of PET-CT imaging. The aim was to evaluate the accuracy of infrared thermography (IRT) in detecting human BAT benchmarked to PET-CT imaging. Seventeen individuals underwent a total of 29 PET-CT scans, 12 of whom were studied twice, after 2 h of cold stimulation at 19°C, in parallel with measurement of skin temperatures overlying the supraclavicular (SCV) fossa and the lateral upper chest (control), before and after cold stimulation. Of the 29 scans, 20 were BAT positive after cold stimulation. The mean left SCV temperature tended to be higher in the BAT-positive group before and during cooling. It was significantly higher (P = 0.04) than the temperature of the control area, which fell significantly during cooling in the BAT-positive (-1.2 ± 0.3°C, P = 0.002) but not in the negative (-0.2 ± 0.4°C) group. The temperature difference (Δtemp) between left SCV and chest increased during cooling in the BAT-positive (1.2 ± 0.2 to 2.0 ± 0.3°C, P < 0.002) but not in the negative group (0.6 ± 0.1 to 0.7 ± 0.1°C). A Δtemp of 0.9°C conferred a positive predictive value of 85% for SCV BAT, superior to that of SCV temperature. The findings were similar on the right. In conclusion, the Δtemp is significantly and consistently greater in BAT-positive subjects. The Δtemp quantified by IRT after 2-h cooling shows promise as a noninvasive convenient technique for studying SCV BAT function.

Epithelial-myoepithelial carcinoma of the tongue base: a case for the case-report and review of the literature.

A 60 year old lady was referred to the Princess Alexandra Hospital (Brisbane, Queensland, Australia) tertiary Otolaryngology, Head and Neck Unit from a peripheral hospital for investigation and management of a tumour at the base of the tongue. Biopsy of the tumour revealed it to be an epithelial-myoepithelial carcinoma of the base of the tongue. This is an extremely rare tumour in this location with only 2 other case reports in the world literature: the patients were treated with chemo-radiotherapy and surgery respectively. Our patient was made aware of the world literature and was able to make a fully informed decision on her choice of treatment modality and was treated with radiotherapy. Increasingly journals are limiting publication of case reports to "world firsts" only. We present a case where such a policy would have denied patient choice and possibly led to detrimental treatment.We review the world literature of tongue base epithelial-myoepithelial carcinoma of the tongue.

MRI features of bone marrow necrosis.

OBJECTIVE: The purpose of this study was to illustrate and review the MRI appearance of histologically proven cases of bone marrow necrosis (BMN) and to review the literature on this clinicopathologic entity with emphasis on its distinction from avascular necrosis (AVN) of bone. CONCLUSION: BMN is a rare clinicopathologic entity separate from AVN and has a distinctive MRI appearance. As MRI comes to play an increasingly important role in the evaluation of bone marrow disease, BMN is likely to be more frequently encountered. Awareness of BMN and its MRI appearance and appreciation of the frequent association between BMN and underlying malignancy may assist in the early diagnosis of BMN and initiate an intensive search for occult malignancy.

Pyramidal tract imaging in multiple-system atrophy.

A new radiological finding of T2 FLAIR hyperintensities in the pyramidal tracts is described in a patient clinically thought to have idiopathic Parkinson's disease but histologically proven to have multiple-system atrophy.