Comparison of FDG PET/MRI and FDG PET/CT in Pediatric Oncology in Terms of Anatomic Correlation of FDG-positive Lesions.

The aims of our study were to compare F-18 fluorodeoxyglucose (FDG) positron-emission tomography/magnetic resonance imaging (PET/MRI) and PET/computed tomography (CT) in pediatric oncology patients in terms of anatomic correlation of FDG-positive lesions, and also to compare diffusion-weighted imaging (DWI) with PET to assess the correlation between apparent diffusion coefficient (ADC) values and standardized uptake value (SUV). Sequential PET/CT and PET/MRI images and/or whole-body DWI and ADC mapping in 34 pediatric patients were retrospectively analyzed. FDG-positive lesions were visually scored for CT, T1-weighted, T2-weighted, and DWI images separately in terms of anatomic correlation of FDG-avid lesions. Correlation analysis was performed for SUV parameters and ADC values. Among 47 FDG-positive lesions identified concurrently on PET/CT and PET/MRI, 37 were positive on CT and 46 were positive on at least one MRI sequence (P=0.012). Among 32 FDG-positive lesions for which DWI were available, 31 could be clearly depicted on DWI, resulting in significant difference compared with CT alone in the detection of FDG-positive lesions. No correlation was found between ADC and SUV. FDG PET/MRI exhibits better performance than PET/CT in terms of anatomic correlation of FDG-avid lesions. Therefore, PET/MRI may be more advantageous than PET/CT, not only due to reduced ionizing radiation dose but also for a better depiction of FDG-avid lesions in pediatric PET imaging.

Could the simplified (14)C urea breath test be a new standard in noninvasive diagnosis of Helicobacter pylori infection?

OBJECTIVE: The carbon-14 ((14)C) urea breath test (UBT) is a reliable and noninvasive technique for the diagnosis of Helicobacter pylori (HP) infection. The diagnostic performance of a new practical and low dose (14)C UBT system (Heliprobe, Stockholm, Sweden) was compared with those of other diagnostic tests, namely, rapid urease test (RUT), histopathology, and DNA detection using polymerase chain reaction (PCR). METHODS: Eighty-nine patients (mean age = 45 +/- 13, 30 men) with dyspeptic complaints who underwent an endoscopic procedure were studied. Biopsy specimens acquired during the procedure were subjected to RUT, histopathological examination using hematoxylin and eosin (HP-HE) and PCR. All patients underwent UBT using the Heliprobe system on a different day. The gold standard for HP positivity was defined as any two of the three tests being positive, excluding UBT, and the sensitivity and specificity of any single test alone were determined using this gold standard. Whenever only one test was positive, it was considered to be a false-positive one. RESULTS: With the gold standard used in this study, 59 (66%) patients were diagnosed HP positive. The Heliprobe method detected HP infection with 96.6% sensitivity and 100% specificity and had the best diagnostic performance when compared with all the other methods. The sensitivity and specificity of the other methods for the detection of HP positivity were 89.8% and 100% for RUT, 93.2% and 63.3% for PCR, and 93.2% and 76.6% for HP-HE, respectively. Areas under the receiver-operating characteristic were 0.977 for UBT, 0.947 for RUT, 0.84 for HP-HE, and 0.775 for PCR. CONCLUSIONS: Using a combination of invasive diagnostic tests as the gold standard, Heliprobe UBT was found to be highly sensitive and specific for the diagnosis of HP infection in patients with dyspeptic complaints.