Virtual Bronchoscopy: An Experimental Study on Parameters Affecting Apparent Sizes of Simulated EndobronchialLesions

PURPOSE: To evaluate the scanning parameters affecting the apparent sizes of endoluminal lesions of thetracheobronchial tree, as seen on virtual bronchoscopy(VB), and to determine the optimal CT parameters fordemonstrating the real sizes of endobronchial lesions. MATERIALS AND METHODS: Spherical beads of 8 mm - 10 mmdiameter were randomly placed in the airways of fixed pig lung. CT scans were obtained with collimation and pitchof 3 mm/1, 3 mm/1.5, and 5mm/1, respec-tively. Volumetric data were reconstructed with 1mm-, 1.5 mm-, and2mm-collimation for each parameter. VBs were reconstructed with shaded-surface technique and soft tissuealgorithm. A 10mm-sized bead in the trachea and two 8 mm-sized beads in the left main bronchus were selected andtheir longest diameters were measured on VB at varying thresholds from -800 to -2 00HU. RESULTS: When themeasured diameters of beads on VB were recorded as the percentage of real sizes, they were 1) 78.9 %, 77.5%, and73.7% at collimations and pitches of 3 mm/1, 3mm/1.5, and 5 mm/1, respectively; 2) 77.9 %, 76.9 %, and 75.1 % at 1mm, 1.5 mm and 2 mm reconstructions, respectively; 3) 86.2 % / 83.4% / 80.4% / 77.0% / 74.8% / 70.2% / 64.5% atisosurface thresholds of -8 0 0 /-7 0 0 /-6 0 0 /-5 0 0 /-4 0 0 /-3 0 0 /-200HU, re-spectively; 4) 85.6 %, 75.0 %,69.3% at 23 mm, 17 mm and 11mm luminal diameters of lesion location, respectively. CONCLUSION: Overall, thediameters of endobronchial lesions are underestimated on VB. As the isosurface threshold values, collimations,pitches and reconstruction interuals decrease in size, the measured diameters approach to real diameter of thebeads. Beads in peripheral airways appear smaller than those in proximal airways.

3 DFT Magnetic Resonance Dacryocystography in the Evaluation of Epiphora

PURPOSE: To evaluate the feasibility of 3-dimensional Fourier transformation magnetic resonancedacryocystography (3DFT MR DCG: MR DCG) and its diagnostic efficacy in patients with epiphora. MATERIALS AND METHODS: Three normal volunteers and ten patients complaining of epiphora were studied by MR DCG using 3DFT CISSand 3DFT FLASH techniques. In normal volunteers, MR DCG was obtained by instillation of diluted Gd-DTPA solutionsof different concentrations (Gd-DTPA : saline=1:100, 1:50, 1:25) using various instillation methods. In patientswith epiphora, MR DCG was compared with conventional D C G . RESULTS: In normal volunteers, the best image wasobtained with the continuous instillation method during MR scanning. In all normal volunteers, MR DCG demonstratedthe entire course of the nasolacrimal duct (NLD). In patients with epiphora, however, there were five cases inwhich MR DCG failed to visualize the NLD, as well as five cases of occlusion and two of stenosis at the level ofthe proximal NLD. These findings corresponded with conventional DCG findings as four cases of occlusion at thelevel of the common canaliculi, one case of lacrimal sac, five cases of occlusion and two cases of stenosis at thelevel of the proximal NLD. There was no significant difference between MR DCG findings using 3DFT CISS and 3DFTFLASH MR techniques. CONCLUSION: MR DCG can detect the correct level of obstruction and differentiate betweenocclusion and stenosis of the NLD in patients with obstruction of the lacrimal drainage system. It may be a usefuldiagnostic method for investigating complicated cases in which conventional DCG is not possible due topost-surgical or traumatic obstruction.

Radiologic Findings of Pulmonary Sarcoidosis: Comparison Between Radiograph and HRCT

PURPOSE: To analyse the radiographic and HRCT findings of pulmonary sarcoidosis and to evaluate thediagnostic usefulness of HRCT MATERIALS AND METHODS: Initial chest radiographs (n=14) and HRCT scans (n=14), anda followup HRCT scan (n=1) from 14 patients (5 men and 9 women;median age, 38 Years) with biopsy proven pulmonarysarcoidosis were analyzed. RESULT: On initial chest radiographs, they showed pulmonary lesions were seenpredominantly in the middle, upper and lower lung zones in four, two and one patient, respectively. Patterns oflesions were reticulonodular opacities (n=4), air-space (n=2), honeycombing(n=1), macronodule(n=1), and cavitarynodule (n=1). In all patients, HRCT scans demonstrated both pulmonary lesions and intrathoracic lymphadenopathy.Pulmonary lesions were seen predominantly in the middle, lower and upper lung zones in nine, three and twopatients, and in the posterior and anterior lung zones in eight and four patients repectively. Lesions werepredominantly micronodules, with perilymphatic distribution (n=12), macronodules with air-bronchogram (n=1),cavitary macronodules (n=1), ground-glass opacity (n=5), consolidation (n=2), and irregular lines (n=8). CONCLUSION: Reticulonodular lesions in the middle lung zone were seen on radiograph, while the most common HRCTfinding was micronodular lesions with perilymhpatic distribution. HRCT is much more sensitive than chestradiograph for the detection of both pulmonary lesions and lymphadenopathy; this modality revealed micronoduleswhich were invisible on chest radiographs.