Influence of blade width and magnetic field strength on the ADC on PROPELLER DWI in head and neck.

PURPOSE: The purpose of this study was to investigate the influence of blade width and magnetic field strength on apparent diffusion coefficient values of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging in the head and neck at 1.5 and 3.0 T magnetic resonance imaging. METHODS: Fifteen healthy volunteers (eight men and seven women; mean age 36.4 ± 10.1 years) underwent PROPELLER diffusion-weighted imaging using four blade widths at 3.0 T and three blade widths at 1.5 T. For the multigroup comparison of apparent diffusion coefficient values, we performed analysis of variance and Tukey-Kramer tests. The apparent diffusion coefficient values in each organ were compared among the different blade widths and magnetic field strengths by a t test. Inter and intra-observer agreements regarding apparent diffusion coefficient value measurements were evaluated using the intraclass correlation coefficient. RESULTS: No significant differences were observed in apparent diffusion coefficient values of the cerebellum in each blade width at both field strengths. The apparent diffusion coefficient values of the right parotid glands were significantly lower for blade width 32 than for blade width 16 at 3.0 T (1.16 × 10-3 mm2/s vs. 1.01 × 10-3 mm2/s; P < 0.05). The apparent diffusion coefficient values of bilateral parotid glands were significantly higher at 1.5 T than at 3.0 T. Intraclass correlation coefficients were almost perfect to substantial in the cerebellum, whereas they showed moderate agreement in the parotid glands. CONCLUSION: The largest blade width 32 at 3.0 T and high magnetic field strength lowered the apparent diffusion coefficient values of parotid glands of PROPELLER diffusion-weighted imaging. The apparent diffusion coefficient values in the parotid glands of PROPELLER diffusion-weighted imaging may be affected for blade width and magnetic field strength.

[Two cases of radiation myositis probably induced by recall phenomenon].

Two cases of radiation myositis following gemcitabine-based chemotherapy for advanced non-small cell lung cancer are presented. In the two cases, myositis appeared 3 and 5.5 months after the completion of radiation therapy and 2 and 2.5 months after the beginning of chemotherapy, respectively. The affected areas, the upper back and right thigh, appeared as areas of increased signal intensity on T2-weighted MR imaging and were enhanced by the administration of Gd-DTPA in the skeletal muscles. These coincided with the previously irradiated area. Although radiation myositis is a rare complication, it is important to be careful of radiation recall induced by chemotherapeutic agents.

HRCT findings of pulmonary complications in non-AIDS immunocompromised patients: are they useful in differential diagnosis?

PURPOSE: This study was designed to evaluate the diagnostic value of characteristic HRCT findings in the differential diagnosis of acute pulmonary complications (APCs) in immunocompromised patients and to investigate how to improve diagnostic accuracy. MATERIALS AND METHODS: We reviewed the chest CT images of 103 consecutive immunocompromised non-AIDS patients with APCs. The presence, extent, and anatomical distribution of the CT findings were assessed by two radiologists. The sensitivity and positive predictive value (PPV) of each criterion determined by the combination of CT findings that were characteristic in previous studies were calculated. RESULTS: The average sensitivity of each criterion was 0.50 in the total cases. There were many false positives, and the PPVs of some criteria were low. Among the significantly less frequent CT findings, the frequency of bronchovascular bundle thickening was 0% in cytomegaloviral pneumonia (CMV P). The absence of this finding improved the diagnostic accuracy of CMV P. CONCLUSION: Because the combination of only characteristic HRCT findings in each disease was of relatively limited value in making a diagnosis, infrequent findings should be also added to the CT criteria to improve accuracy.

Air trapping at CT: high prevalence in asymptomatic subjects with normal pulmonary function.

PURPOSE: To determine the degree and extent of air trapping at computed tomography (CT) in subjects with normal pulmonary function test results. MATERIALS AND METHODS: The study group consisted of 50 subjects with normal pulmonary function, including 26 nonsmokers and 24 smokers (14 current and 10 ex-smokers; 11 mild and 13 heavy smokers). All 50 subjects underwent thin-section CT at which images were obtained during deep inspiration and expiration at three lung levels. The mean expiratory increase in lung attenuation was measured at each level. Air trapping was visually classified into four degrees (none, lobular, mosaic, or extensive), and the extent of air trapping was also semiquantitatively calculated. The visual grade and semiquantitative ratio of air trapping were compared among nonsmokers, current smokers, and ex-smokers and among nonsmokers, mild smokers, and heavy smokers by using the Kruskal-Wallis rank test and the Fisher protected least significant difference test, respectively. RESULTS: The mean increase in lung attenuation in the three levels at expiration was 111.9 HU +/- 46.3 (SD). The overall frequency of air trapping was 64%. Lobular, mosaic, and extensive air trapping were seen in 10 (20%), 14 (28%) and eight (16%) patients, respectively. There was no significant difference in the visual grade of air trapping among the nonsmokers, current smokers, and ex-smokers (P =.387) or among the nonsmokers, mild smokers, and heavy smokers (P =.231). There was also no significant difference in the semiquantitative ratio of air trapping among nonsmokers, current smokers, and ex-smokers (P =.859) or among nonsmokers, mild smokers, and heavy smokers (P =.897). CONCLUSION: Various degrees of air trapping, including the mosaic or extensive types, can be observed in subjects with normal pulmonary function and have no correlation with the subject's current smoking status or cigarette consumption.

HRCT findings of chest complications in patients with leukemia.

High-resolution CT (HRCT) findings of several chest complications occurring in leukemic patients were reviewed. Although most entities show non-specific HRCT findings including ground-glass opacity and air-space consolidation, characteristic findings are observed in several pulmonary complications including Pneumocystis carinii pneumonia, fungal infections, miliary tuberculosis, leukemic infiltration, pulmonary edema, bronchiolitis obliterans, and bronchiolitis obliterans organizing pneumonia. A combination of these characteristic HRCT findings and the information obtained from the clinical setting may help in achieving a correct diagnosis of chest complications occurring in leukemic patients.

CT findings of leukemic pulmonary infiltration with pathologic correlation.

The aim of this study was to demonstrate the characteristic CT findings of leukemic pulmonary infiltration based on the pathologic findings. The CT findings of 11 leukemic patients with leukemic pulmonary infiltration were compared with those of 22 leukemic patients with other diseases as a control group. Evaluated pulmonary parenchymal CT findings included thickening of bronchovascular bundles and interlobular septa, prominence of peripheral pulmonary arteries, ground-glass opacities, air-space consolidation, and nodules. The CT-pathologic correlations for leukemic infiltration were evaluated in 7 patients. Frequent parenchymal CT findings were thickening of bronchovascular bundles (81.8%), prominence of peripheral pulmonary arteries (81.8%), and non-lobular and non-segmental ground-glass opacities (90.9%). The first two findings were significantly more frequently observed in leukemic infiltration than in the control group, had good interobserver agreement, and corresponded pathologically to leukemic cell infiltration around the pulmonary arteries, bronchi, or bronchioles. Non-lobular and non-segmental ground-glass opacity corresponded to leukemic cell infiltration within alveolar spaces and septa adjacent to the pulmonary arteries or bronchi and also corresponded to hemorrhage, edema, or diffuse alveolar damage. Thickening of bronchovascular bundles and prominence of peripheral pulmonary arteries are CT findings suggestive for leukemic infiltration and correspond to peribronchovascular tumor extension.