CT ventilation imaging derived from breath hold CT exhibits good regional accuracy with Galligas PET.

BACKGROUND AND PURPOSE: CT ventilation imaging (CTVI) derived from four dimensional CT (4DCT) has shown only moderate spatial accuracy in humans due to 4DCT image artefacts. Here we assess the accuracy of an improved CTVI using high quality exhale/inhale breath-hold CT (BHCT). MATERIALS AND METHODS: Eighteen lung cancer patients underwent exhale/inhale BHCT, 4DCT and Galligas PET ventilation scans in a single imaging session. For each BHCT and 4DCT scan, we performed deformable image registration (DIR) between the inhale and exhale phase images to quantify ventilation using three published metrics: (i) breathing induced lung density change, CTVIDIR-HU (ii) breathing induced volume change CTVIDIR-Jac and (iii) the regional air-tissue product, CTVIHU Spatial accuracy was reported as the voxel-wise Spearman correlation r between CTVI and Galligas PET. RESULTS: For BHCT-based CTVIs (N = 16), the CTVIDIR-HU, CTVIDIR-Jac and CTVIHU methods yielded mean (range) r values of 0.67 (0.52-0.87), 0.57 (0.18-0.77) and 0.49 (0.14-0.75) respectively. By comparison the 4DCT-based CTVIs (n = 14) had values of 0.32 (-0.04 to 0.51), 0.16 (-0.31 to 44) and 0.49 (0.20-0.77) respectively. CONCLUSIONS: High quality CT imaging is a key requirement for accurate CT ventilation imaging. The use of exhale/inhale BHCT can improve the accuracy of CTVI for human subjects.

Measurement of preoperative lobar lung function with computed tomography ventilation imaging: progress towards rapid stratification of lung cancer lobectomy patients with abnormal lung function.

OBJECTIVES: In lung cancer preoperative evaluation, functional lung imaging is commonly used to assess lobar function. Computed tomography ventilation (CT-V) imaging is an emerging lung function imaging modality. We compared CT-V imaging assessment of lobar function and its prediction of postoperative lung function to that achieved by (i) positron emission tomography ventilation (PET-V) imaging and (ii) the standard anatomical segment counting (ASC) method. We hypothesized (i) that CT-V and PET-V have similar relative lobar function and (ii) that functional imaging and anatomic assessment (ASC) yield different predicted postoperative (ppo) lung function and therefore could change clinical management. METHODS: In this proof-of-concept study, 11 patients were subjected to pulmonary function tests, CT-V and PET-V imaging. The Bland-Altman plot, Pearson's correlation and linear regression analysis were used to assess the agreement between the CT-V-, PET-V- and ASC-based quantification of lobar function and in the ppo lung function. RESULTS: CT-V and PET-V imaging demonstrated strong correlations in quantifying relative lobar function (r = 0.96; P < 0.001). A Wilcoxon-signed rank test showed no significant difference in the lobar function estimates between the two imaging modalities (P = 0.83). The Bland-Altman plot also showed no significant differences. The correlation between ASC-based lobar function estimates with ventilation imaging was low, r < 0.45; however, the predictions of postoperative lung function correlated strongly between all three methods. CONCLUSIONS: The assessment of lobar function from CT-V imaging correlated strongly with PET-V imaging, but had low correlations with ASC. CT-V imaging may be a useful alternative method in preoperative evaluation for lung cancer patients.

(67)Ga SPECT/CT accurately localized recurrent hepatic cyst infection in patients with autosomal dominant polycystic kidney disease.

Hepatic pyocyst is a rare but potentially life-threatening complication of autosomal dominant polycystic kidney disease. With extensive hepatic cystic disease, localization of a pyocyst and targeted aspiration or drainage is often a diagnostic challenge. Two patients with autosomal dominant polycystic kidney disease and recurrent gram-negative sepsis were imaged with Ga SPECT/CT for investigation of an infective source. In both patients, imaging accurately localized infected pyocysts and guided percutaneous drainage and further management.

SPECT/CT in V/Q scanning.

Combining the functional data provided by single-photon emission computed tomography (SPECT) with the anatomical information provided by CT has been shown to improve overall diagnostic accuracy in many areas of nuclear medicine. Although planar lung scans have often relied on correlation with a chest x-ray to help optimize scan interpretation, the advent of 3D lung imaging with SPECT provides the opportunity to combine lung perfusion data with CT images. This can be done by performing the study on a hybrid SPECT/CT scanner, with the CT acquisition typically performed with the use of low-dose parameters, rather than full diagnostic quality settings, or by software fusion with a fully diagnostic CT or a contrast-enhanced CT pulmonary angiogram. Such an approach has been shown to improve specificity and overall accuracy of ventilation/perfusion scintigraphy as well as facilitating more accurate clot localization. With the increased availability of hybrid SPECT/CT scanners, such an approach can be implemented in most imaging departments with little additional acquisition time or radiation dose. Misregistration caused by respiratory motion can impact combined studies, although this can be minimized with attention to patient breathing patterns during image acquisition. For patients with lung cancer, ventilation/perfusion SPECT/CT may have a role in allowing the optimal selection of radiotherapy fields and can improve the preoperative quantification of lung function before resection.

Risks of outpatient angiography and interventional procedures: a prospective study.

OBJECTIVE: The purpose of this study was to evaluate complications in diagnostic and interventional angiographic procedures performed on outpatients. MATERIALS AND METHODS: Data were collected prospectively for 2,683 procedures performed on an outpatient basis in 2,248 patients from the period March 1997 to March 2002. Patients were assessed by nursing or medical staff within 2-4 hr of the procedure and again via telephone 24-48 hr after the procedure. The collected data were summarized on the basis of procedure type into four main groupings: aortofemoral studies, cerebral studies, interventional procedures, and other studies. Complication frequency distribution was determined for each procedure type. An interim summary of complication rates was prepared for the period March 1997 to June 1999. Statistical analysis using a two-tailed z-test for the comparison of two proportions was performed to determine if a significant difference existed in the rates of complications from data collected before and after the June 1999 summary. RESULTS: Ninety-one percent of cases completed follow-up. In total, 561 complications were identified in 2,436 cases (23%). Most complications consisted of either local pain or puncture site hematoma and bruising. No deaths occurred. In the 1,128 diagnostic aortofemoral studies performed, 211 complications (19%) occurred. In the 359 cerebral studies, 87 complications (24%) occurred. The 441 interventional procedures resulted in 146 complications (33%). In the remaining 508 procedures, 117 complications (23%) occurred. Major complications in each group are presented. CONCLUSION: We observed a low incidence of complications requiring further treatment or resulting in a permanent deficit. The rates are comparable to published data from similar studies and practice standards guidelines. A statistically significant improvement was seen in the total complication rate between the periods March 1997-June 1999 and July 1999-March 2002 (p = 0.01).