Quantitative Pulmonary Perfusion Imaging with 3-dimensional, Contrast-enhanced MR: Regional Difference in the Perfusion Parameters of Healthy Volunteers

PURPOSE: We wanted to evaluate the regional differences in such perfusion parameters as pulmonary blood flow (PBF), mean transit time (MTT) and pulmonary blood volume (PBV) in the entire lung of healthy volunteers with using three-dimensional, contrast-enhanced MR imaging (3D CEMRI). MATERIALS AND METHODS: Six healthy volunteers underwent dynamic 3D CEMRI (TR/TE 2.7/0.6 msec; flip angle 40degree; matrix 128x96; reconstructed matrix 256x192; rectangular field of view 450x315 mm; coronal 100-150mm-thickx10 slabs; temporal resolution 1.0 sec; 35 dynamic phases) For all subjects, 2 mL of Gd-DTPA mixed with 3 ml of physiologic saline was administered as a bolus at a rate of 5 mL/sec, and this was followed by 20 mL of physiologic saline flush. From the signal intensity-time curves, the PBF, MTT and PBV maps were generated using indicator dilution theories and the central volume principle on a pixel-by-pixel basis. A total of 54 round, 1-cm sized ROIs were placed in the lung in each subject (6 ROIs per slabx9 slices except for the most posterior slab). The regional differences of the measured parameters were statistically evaluated in the gravitational direction and in the upper-mid-lower direction by one-way ANOVA tests. RESULTS: The calculated PBF, MTT and PBV in the entire lung were 141.8+/-53.4 mL/100 mL/min (mean+/-SD), 5.35+/-1.38 sec, and 13.4+/-6.48 mL/100mL, respectively. In the gravitational direction, there was a significant increase in the PBF and PBV as it goes to the posterior direction (p < 0.05). No statistical difference was found in PBF or PBV between the upper, mid and lower lung zone areas. CONCLUSION: Regional difference in the various perfusion parameters of the lung in healthy volunteers can be quantitatively assessed with performing 3D CEMRI.

Systemic Arterial Supply to the Normal Basal Segments of the Left Lower Lobe: Case Report

Systemic arterial supply to the normal basal segments of the left lower lobe is a rare congenital anomaly which has characteristic radiologic features. The lung supplied by the anomalous systemic artery has a normal bronchial tree. We recently encountered a case in which the diagnosis of systemic arterial supply to the normal basal segments of the left lower lobe was strongly suggested by the chest radiographic, CT, and MRI findings. The diagnosis was subsequently confirmed by left lower lobectomy.

An Experimental Study of Exo genous Lipoid Pneumonia: Sequential Changes in High-Resolution CT and MR Findings

PURPOSE: To evaluate sequential changes in high-resolution CT(HRCT) and MR findings of exogenous lipoidpneumonia in rabbits and to compare the radiologic and histopathologic findings. MATERIALS AND METHODS: A singleendobronchial administration of shark liver oil(0.5 or 1 ml/kg of body weight) was given to 25 rabbits. HRCT scanswere obtained immediately(n=17), at 1 day(n=14), 3 days(n=10), 1 week(n=15), 2 weeks(n=10), 4 weeks(n=9), 6weeks(n=5), 8 weeks(n=6), 10 weeks(n=4), 12 weeks(n=2), 14 weeks(n=3), and 16 weeks(n=2) after administration.Changes in distribution, extent, and attenuation were assessed on HRCT scans. MR scans were obtainedimmediately(n=12), at 1 day(n=9), 3 days(n=9), 1 week(n=15), 2 weeks(n=9), 4 weeks(n=11), 6 weeks(n=5), 8weeks(n=7), 10 weeks(n=3), 14 weeks(n=3), and at 16 weeks(n=2) after administration. Changes in distribution,extent, and signal intensity were assessed on MR scans. In 16 rabbits, CT and MR findings were compared withhistopatholo-gic findings obtained in the same plane. RESULTS: HRCT findings included consolidation withair-bronchogram, ground-glass attenuation and fat attenuation within the lesion at earlier stages(immediate-2weeks). The extent of lesions was greatest at 1 week, and was then seen to gradually decrease on follow-up CTscans. T1-weighted MR images(T1WI) showed high or intermediate signal intensity(SI) at earlier stages andintermediate SI at later stages, while T2-weighted MR images(T2WI) showed high SI at both earlier and laterstages. Histopathologic correlation showed that ground-glass attenuation and consolidation on HRCT reflectedintraalveolar lipid-laden macrophages, cuboidal metaplasia of alveolar epithelial cells, and alveolar septalwidening with inflammatory cell infiltration. Maximal infiltration of oil in the lung correlated closely with thepeak low-attenuation seen on CT scans and the high signal intensity seen on T1WI. CONCLUSION: Shark liveroil-induced exogenous lipoid pneumonia in rabbits is reliably diagnosed by HRCT and MR during earlier stages(1-2weeks). The absence of fat at later stages cannot exclude for certain a diagnosis of exogenous lipoid pneumonia.