Relationship between a chronically painful trapezius muscle and its metabolic state analyzed with PET/CT.

OBJECTIVES: The aim of this study was to investigate the intramuscular metabolic state in chronically painful muscles using positron-emission tomography/computerized tomography (PET/CT). STUDY DESIGN: The study included 140 consecutive noncancer subjects who underwent PET/CT screening for a physical checkup (mean age 56.0 +/- 10.22 y). The demographic data and information on pain in the neck/shoulder region were obtained using a questionnaire. The subjects who had an awareness of pain in the neck/shoulder region for >6 months were regarded to be pain subjects (n = 39). The minimal and maximal standardized uptake values (SUV) of [(18)F]fluorodeoxyglucose ((18)F-FDG) of the trapezius muscle in each subject were automatically calculated. RESULTS: The unpaired t test revealed that both the minimal and the maximal SUVs were significantly lower in the pain subjects than in the asymptomatic subjects. A multiple linear regression analysis also demonstrated a significant association between pain in the neck/shoulder region and the SUVs in the trapezius muscle. CONCLUSIONS: Uptake of (18)F-FDG was lower in the chronically painful trapezius muscle.

Basic study of susceptibility-weighted imaging at 1.5T.

With the aim of sequence optimization in susceptibility-weighted imaging (SWI), 2 image acquisition parameters (slice thickness and matrix size) and 2 image processing conditions (number of slices per minimum intensity projection (MIP) and Sliding Window) were investigated using a 1.5-T magnetic resonance imaging (MRI) system. The subjects were 12 healthy volunteers and the target region for scanning was the whole brain. Informed consent was obtained from all subjects. First, susceptibility-weighted images were acquired with various slice thicknesses from 1mm to 5mm and various matrix sizes from 256 x 256 to 512 x 512, and the images were assessed in terms of the contrast-to-noise ratio (CNR) and were also visually evaluated by three radiologists. Then, the number of slices per MIP and the usefulness of the Sliding Window were investigated. In the study of the optimal slice thickness and matrix size, the results of visual evaluation suggested that a slice thickness of 3mm and a matrix size of 448 x 448 are optimal, while the results of evaluation based on CNR were not significant. As regards the image processing conditions, the results suggested that the number of slices per MIP should be set to a minimum value of 2 and that the use of Sliding Window is effective. The present study provides useful reference data for optimizing SWI sequences.

Differential diagnosis of adrenal masses by chemical shift and dynamic gadolinium enhanced MR imaging.

Chemical shift MRI is widely used for identifying adenomas, but it is not a perfect method. We determined whether combined dynamic MRI methods can lead to improved diagnostic accuracy. Fifty-seven adrenal masses were examined by chemical shift and dynamic MR imaging using 2 MR systems. The masses included 38 adenomas and 19 non-adenomas. In chemical shift MRI studies, the signal intensity index (SI) was calculated, and the lesions classified into 5 types in the dynamic MRI studies. Of the 38 adenomas studied, 37 had an SI greater than 0. In the dynamic MRI, 34 of 38 adenomas showed a benign pattern (type 1). If the SI for the adenomas in the chemical shift MRI was considered to be greater than 0, the positive predictive value was 0.9, and the negative predictive value was 0.94 and kappa = 0.79. If type 1 was considered to indicate adenomas in the dynamic MRI, the corresponding values were 0.94, 0.81 and kappa = 0.77 respectively. The results obtained when the 2 methods were combined were 1, 0.95 and kappa = 0.96 respectively. The chemical shift MRI was found to be useful for identifying adenomas in most cases. If the adrenal mass had a low SI (0 < SI < 5), dynamic MRI was also found to be helpful for making a differential diagnosis.

MR imaging of renal cell carcinoma: associations among signal intensity, tumor enhancement, and pathologic findings.

The purpose of this study was to compare the MR characteristics of renal cell carcinomas against histologic findings and to assess the correlations among signal intensity, tumor enhancement, and pathologic findings. Fifty-four patients (56 lesions) were examined by MR imaging and then underwent partial or radical nephrectomy. The pathologic diagnosis of all lesions was renal cell carcinoma. All MR examinations were performed as dynamic studies using the same 1.5-T scanner. MR characteristics were compared against pathologic findings after resection, and the correlations among signal intensity, tumor enhancement, and pathologic findings were then assessed. A significant correlation was observed between tumor grade and tumor enhancement, with G3 lesions tending to show little enhancement. Regardless of the histologic classification, G3 tumors were found to contain highly heterotypic cancer cells and very few vessels by histopathologic examination. No significant correlations were noted between the other MR characteristics and pathologic findings. Renal cell carcinomas showing little enhancement tend to be highly malignant lesions based on the pathologic findings. Special consideration is required for these tumors with regard to the selection of surgical intervention and follow-up observation.

Hepatectomy simulation discrepancy between radionuclide receptor imaging and CT volumetry: influence of decreased unilateral portal venous flow.

BACKGROUND: Regional dysfunction demonstrated by Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (GSA) scintigraphy due to regional decrease in the portal venous flow has previously been reported. In this study, we call attention to the significance of unilateral portal venous flow decrease for preoperative hepatectomy simulation, and evaluate the hepatectomy simulation discrepancy between Tc-99m-GSA single-photon emission computed tomography (SPECT) and CT volumetry. METHODS: Twenty-four hepatectomy candidates underwent preoperative hepatectomy simulation by both Tc-99m-GSA SPECT and CT volumetry. Both anatomical and functional resection ratios were calculated by means of CT volumetry and Tc-99m-GSA SPECT, respectively. The differences and ratios between anatomical and functional resection ratios were calculated in all patients, and compared in patients with and without unilateral portal venous flow decrease. RESULTS: Anatomical resection ratios were 28.0 +/- 11.7 (mean +/- standard deviation) in patients with unilateral portal venous flow decrease, and 42.1 +/- 15.7 in patients without unilateral portal venous flow decrease (p = 0.0127). Functional resection ratios were 14.7 +/- 12.8 in patients with unilateral portal venous flow decrease and 40.5 +/- 14.6 in patients without (p = 0.0004). The differences between anatomical and functional resection ratios were 13.0 +/- 7.9 in patients with unilateral portal venous flow decrease and 5.6 +/- 3.1 in patients without (p = 0.0099). The ratios between anatomical and functional resection ratios were 0.48 +/- 0.29 in patients with unilateral portal venous flow decrease and 0.86 +/- 0.10 in patients without (p = 0.0018). In 12 of the 13 patients with unilateral portal venous flow decrease, anatomical resection ratios were found to be larger than functional resection ratios, whereas this happened in only 6 of 11 patients without unilateral portal venous flow decrease (p = 0.0063). CONCLUSION: Unilateral portal venous flow decrease is suspected to be a major factor in the discrepancy between hepatectomy simulations with radionuclide receptor imaging and CT volumetry.