Using the MDCT thick slab MinIP method for the follow-up of pulmonary emphysema.

PURPOSE: The purpose of this study was to evaluate the usefulness of thick slab minimum intensity projection (MinIP) as a follow-up method in patients with pulmonary emphysema. This method was used to determine the presence or absence of changes over time in the lung field based on multi-detector-row CT (MDCT) data. METHODS: Among patients diagnosed with pulmonary emphysema who underwent 16-MDCT (slice thickness, 1 mm) twice at an interval of 6 months or more, 12 patients without changes in the lung field and 14 with clear changes in the lung field were selected as subjects. An image interpretation experiment was performed by five image interpreters. Pulmonary emphysema was followed up using two types of thick slab MinIP (thick slab MinIP 1 and 2) and multi-planar reformation (MPR), and the results of image interpretation were evaluated by receiver operating characteristic (ROC) analysis. In addition, the time required for image interpretation was compared among the three follow-up methods. RESULTS: The area under the ROC curve (Az) was 0.794 for thick slab MinIP 1, 0.778 for the thick slab MinIP 2, and 0.759 for MPR, showing no significant differences among the three methods. Individual differences in each item were significantly more marked for MPR than for thick slab MinIP. The time required for image interpretation was around 18 seconds for thick slab MinIP 1, 11 seconds for thick slab MinIP 2, and approximately 127 seconds for MPR, showing significant differences among the three methods. CONCLUSION: There were no significant differences in the results of image interpretation regarding the presence or absence of changes in the lung fields between thick slab MinIP and MPR. However, thick slab MinIP showed a shorter image interpretation time and smaller individual differences in the results among image interpreters than MPR, suggesting the usefulness of this method for determining the presence or absence of changes with time in the lung fields of patients with pulmonary emphysema.

Evaluation of pulmonary lobe variations using multidetector row computed tomography.

PURPOSE: To examine incomplete pulmonary lobes and their variations using multiplanar reformation (MPR) techniques of isotropic voxel data produced by multidetector row computed tomography (CT). MATERIALS AND METHODS: The subjects were 1000 patients who underwent thoracic CT. All examinations were performed using 16-row multidetector CT with a slice thickness of 1 mm. Interlobar fissures were observed by scrolling MPR techniques for various directions. RESULTS: Incomplete interlobar fissure was observed in 42.2% of subjects. Incomplete interlobar fissures between the right upper and middle lobes were observed in 20.4% of subjects, right major fissure was recorded in 17.4%, and left major fissure in 19.2%. Excessive fissure formation was observed in 8% of subjects (4 lobes on the right in 5.7%, 3 lobes on the left in 2.3%). Approximately half of the subjects with incomplete interlobar fissures had coexisting abnormalities in other lobes, whereas approximately one third of those with excessive fissures had coexisting abnormalities in other lobes. CONCLUSIONS: The incidence of incomplete lobulation observed by multidetector CT in this study is remarkably lower than that reported in previous CT studies but is comparable with that reported from autopsy results. It is important to perform multidirectional observation using MPR.