Single-shot half-Fourier RARE sequence with ultra-short inter-echo spacing for lung imaging.

PURPOSE: To improve the image quality of pulmonary magnetic resonance (MR) imaging using an ultra-short inter-echo spacing half-Fourier single shot rapid acquisition with relaxation enhancement (USHA-RARE) sequence. MATERIALS AND METHODS: Pulmonary MR images were acquired by USHA-RARE sequence with various inter-echo spacings. The sequence parameters were as follows: repetition time (TR)/effective TE: infinite/39-41 msec; section thickness: 10 mm; acquisition matrix: 128 x 128; field of view: 450 x 450 mm. Inter-echo spacing varied (2.5 msec, 3.0 msec, 3.5 msec, 4.0 msec, 4.5 msec, 5.0 msec), and the respective phase-encoding steps were 80, 77, 75, 74, 73, and 72. Signal-to-noise ratios (SNRs), the signal ratios between lung and fat (lung-to-fat ratio: LFRs), and the signal ratios between the lung and the serratus anterior muscle (lung-to-muscle ratio: LMRs) of each inter-echo spacing were calculated, and statistically evaluated. RESULTS: The SNRs at inter-echo spacings of < or = 3.0 msec were significantly higher than those > or = 4.0 msec (P < 0.05). The LFRs and LMRs at inter-echo spacing < or = 3.0 msec were significantly higher than those > or = 4.0 msec (P < 0.05). CONCLUSION: USHA-RARE sequence does improve signal intensity from the lung.

Voxelwise mapping of magnetic resonance ventilation-perfusion ratio in a porcine model by multimodality registration: technical note.

RATIONALE AND OBJECTIVES: The purpose of this study was to demonstrate the construction of voxelwise ventilation-perfusion (V/Q) ratio maps in a porcine model by nonrigidly aligning the respective ventilation and perfusion images using a multimodality registration algorithm. MATERIALS AND METHODS: The first-pass contrast agent technique for a blood flow map and 3He used for ventilation imaging were performed using a normal porcine model. The registered 3He-ventilation image was then aligned to the blood flow map using a multimodality registration algorithm. The voxelwise V/Q ratios were calculated by dividing the registered 3He-ventilation image by the blood flow map. The V/Q ratios were also semi-logarithmically scatter-plotted against the number of voxels. RESULTS: From perfusion magnetic resonance images, a voxel-by-voxel blood flow map was produced. Registered 3He ventilation image was successfully obtained as well as V/Q ratio map. Plots of the V/Q ratios obtained by this registration approach were similar to the logarithmic normal distribution. CONCLUSION: Registration of MR perfusion and ventilation images can potentially enable quantitative evaluation of regional pulmonary function and thus yield deeper insight into the physiology and pathophysiology of the lung.

Radiological findings in total colon aganglionosis and allied disorders.

OBJECTIVE: The aim of this study was to review the radiological findings of three cases of total colon aganglionosis (TCA), hypoganglionosis, and immature ganglionosis, and to compare the differences in diagnosis and follow-up of these three disease entities. MATERIALS AND METHODS: Three neonates with neonatal onset of abdominal distension with vomiting were investigated, and the cases were diagnosed as TCA, hypoganglionosis, and immature ganglionosis, respectively. Radiological examination of each neonate was performed during the neonatal period and at follow-up. RESULTS: A plain abdominal radiograph showed massive abdominal bowel gas and multiple air-fluid levels in all cases. Barium enema findings including no transition zone, normal rectosigmoid index, reflux of barium into a dilated ileum, and retention of barium on delayed film were observed in all three cases. In aganglionosis and hypoganglionosis, a normal-sized colon, irregular contraction, shortening of the colon, and lack of redundancy were observed. In immature ganglionosis, microcolon was present but there was no shortening of the colon or loss of redundancy. Barium studies following ileostomy during childhood revealed no efficient peristalsis after the neonatal period in patients with aganglionosis and hypoganglionosis. Conversely, the patient with immature ganglionosis showed maturity of colonic function on barium studies after infancy. CONCLUSION: The clinical and radiological findings of TCA and allied disorders are similar in neonates. Sequential contrast intestinal studies could reveal peristalsis of the colon wall, suggesting maturity of the ganglion cells.

Abdominal imaging at 4 T MR system: a preliminary result.

In this study, the potential for abdominal MR images at 4 T using a tailored coil was demonstrated using healthy volunteers. These images were compared with those obtained in the same subject at 1.5 T to discuss whether 4 T would be superior to 1.5 T in abdominal imaging. MR images at 4 T were characterized by high contrast and signal-to-noise ratios, more than 2.95 times higher than those at 1.5 T. In conclusion, abdominal MR imaging at 4 T was feasible. Furthermore, abdominal MR imaging at 4 T was superior to that at 1.5 T in qualitative and quantitative analyses.

Large coalescent parenchymal nodules in pulmonary sarcoidosis: "sarcoid galaxy" sign.

OBJECTIVE: The purpose of this study was to evaluate the large parenchymal nodules in pulmonary sarcoidosis and to describe a new CT sign termed the "sarcoid galaxy." CONCLUSION: The CT appearance of pulmonary sarcoidosis suggests that the large nodules arise from a coalescence of small nodules. The large nodules are surrounded by many tiny satellite nodules. These findings were considered to simulate the appearance of a galaxy. This observation was supported by radiologic-pathologic correlation. The sarcoid galaxy sign may be a useful adjunct in the diagnosis of pulmonary sarcoidosis.