Bending percutaneous drainage catheters to facilitate CT-guided insertion using curved trocar technique

PURPOSE

To assess the safety and efficacy of placing thoraco-abdominal drainage catheters under CT-guidance using a curved trocar technique.

METHODS

A retrospective study of 182 CT/CT-fluoroscopy-guided thoraco-abdominal catheter drainages was conducted; half were performed by residents or fellows under the supervision of one radiologist (Group 1) and the other half under the supervision of 10 other radiologists (Group 2). Group 1 procedures employed a curved catheter assembly placed using trocar technique (n = 44) or straight catheters placed with Seldinger technique (n = 47). Group 2 procedures employed a straight catheter placed using trocar technique (n = 16) or straight catheters placed with Seldinger technique (n = 75). Technical success, procedure time, radiation dose (CT Dose Index CTDI_vol), and adverse events (Common Terminology Criteria for Adverse Events, 4.0) were compared between techniques and groups using Student's t test, Fisher's exact test or Chi-square analysis.

RESULTS

All procedures in groups 1 and 2 were technically successful. Mean procedure time for Group 1 curved trocar technique (28 ± 8 min) was shorter than groups 1 and 2 Seldinger technique (37 ± 11 min, p = .00002). Mean CTDI_vol for Group 1 curved trocar technique (107.8 ± 54.2 mGy) was lower than groups 1 and 2 Seldinger technique (136.1 ± 99.7 mGy, p = 0.032). Adverse event rates for curved trocar, straight trocar, and Seldinger techniques were 2.3% (1/44), 0% (0/16), and 3.3% (4/122), respectively (p = 1); all were grade 1 or 2, and no catheter malfunctions occurred.

CONCLUSIONS

The curved catheter trocar technique is a safe and effective modification of the standard trocar technique that may facilitate CT-guided procedures impeded by CT gantry size limitations.

Incidence and clinical sequelae of portal and hepatic venous thrombosis following percutaneous cryoablation of liver tumors

PURPOSE

To assess the incidence and sequelae of portal and hepatic venous thrombosis after percutaneous cryoablation of hepatic tumors.

METHODS

From November 1998 through December 2010, 223 hepatic tumors were cryoablated during 170 ablation procedures in 135 patients. 24-h post-procedure MR images were reviewed retrospectively by two abdominal radiologists in consensus to identify tumor ablations that developed one or more new portal or hepatic venous thromboses in or outside the ablation zone. On follow-up MRI and CT examinations the outcomes of thromboses were classified as resolved, partially recanalized, persistent, or propagated.

RESULTS

Venous thrombosis developed in association with 54 (24%) of 223 tumor ablations treated during 53 (31%) ablation procedures in 39 (28.8%) patients (15 women, 24 men; age range 40-82 years, mean 59 years). Of these 54 thromboses, 49 (91%) were located in portal vein branches, four (7%) in both portal and hepatic vein branches, and one (2%) in a hepatic vein branch. Thrombosed veins were outside but abutted the ablation zone in 36 (66.7%), and within it in 18 (33.3%). On follow-up imaging (n = 49), thrombi resolved in 29 (59%), partially recanalized in two (4%), persisted in 18 (37%) and propagated from sub-segmental or segmental branches to the left or right portal branches in five (10%). No thrombus propagated to the main portal vein or inferior vena cava.

CONCLUSION

Portal and hepatic vein branch thromboses are common in small branches following percutaneous cryoablation of hepatic tumors and most resolve spontaneously without sequelae.

An Immersive Virtual Reality Environment for Diagnostic Imaging

Purpose: Advancements in and adoption of consumer virtual reality (VR) are currently being propelled by numerous upcoming devices such as the Oculus Rift. Although applications are currently growing around the entertainment field, wide-spread adoption of VR devices opens up the potential for other applications that may have been unfeasible with past implementations of VR. A VR environment may provide an equal or larger screen area than what is provided with the use of multiple conventional displays while remaining comparatively cheaper and more portable making it an attractive option for diagnostic radiology applications. Methods A VR application for the viewing of multiple image slices was designed using: the Oculus Rift head-mounted display (HMD), Unity, and 3D Slicer. Volumes loaded within 3D Slicer are sent to a Unity application that proceeds to render a scene for the Oculus Rift HMD. Users may interact with the images adjusting windowing and leveling using a handheld gamepad controller. Multiple images may be brought closer to the user for detailed inspection. Results Application usage was demonstrated with the simultaneous visualization of longitudinal slices of a serial CT scan of a patient with a lung nodule. Pilot studies for validating usage of the VR system for differential diagnosis and remote collaboration were performed. Initial results suggest that using the VR system increased both task load and time taken to complete tasks, however, the resulting accuracy in assessing nodule growth of nodules was not significantly different than that achieved using a DICOM viewer application on a traditional display.

CT-guided percutaneous cryoablation of central lung tumors

PURPOSE

Cryoablation has been successfully used to treat lung tumors. However, the safety and effectiveness of treating tumors adjacent to critical structures has not been fully established. We describe our experience with computed tomography (CT)-guided percutaneous cryoablation of central lung tumors and the role of ice ball monitoring.

MATERIALS AND METHODS

Eight patients with 11 malignant central lung tumors (nine metastatic, two primary; mean, 2.6 cm; range, 1.0-4.5 cm) located adjacent to mediastinal or hilar structures were treated using CT-guided cryoablation in 10 procedures. Technical success and effectiveness rates were calculated, complications were tabulated and intraprocedural imaging features of ice balls were described.

RESULTS

All procedures were technically successful; imaging after 24 hours demonstrated no residual tumor. Five tumors recurred, three of which were re-ablated successfully. A hypodense ice ball with well-defined margin was visible during the first (n=6, 55%) or second (n=11, 100%) freeze, encompassing the entire tumor in all patients, and abutting (n=7) or minimally involving (n=4) adjacent mediastinal and hilar structures. Pneumothorax developed following six procedures (60%); percutaneous treatment was applied in three of them. All patients developed pleural effusions, with one patient requiring percutaneous drainage. Transient hemoptysis occurred after six procedures (60%), but all cases improved within a week. No injury occurred to mediastinal or hilar structures.

CONCLUSION

CT-guided percutaneous cryoablation can be used to treat central lung tumors successfully. Although complications were common, they were self-limited, treatable, and not related to tumor location. Ice ball monitoring helped maximize the amount of tumor treated, while avoiding critical mediastinal and hilar structures.

A procedural sedation quality improvement audit form tool for interventional radiology

As the number of interventional radiology (IR) procedures performed in the United States increases, so does the need for procedural sedation (PS) performed outside the operating room. PS is not without risk, and without the use of proper guidelines and adequate training, adverse outcomes can occur. Improved oversight and evaluation of PS practice are necessary. This concept paper presents a method to incorporate a quality improvement tool in the IR suite that can be implemented at any healthcare center. This tool was created by radiologists, anesthesiologists, and nurses performing PS and evaluates preprocedural, intraprocedural, and postprocedural steps related to effectiveness of sedation, safety practices, and communication. It was implemented in the IR suite at a large tertiary care hospital. The goal of this study is to show that the tool is practical and easily implementable in any tertiary center and can be used as a quality measure to assess outcomes of PS.

Percutaneous cryoablation of hepatic tumors adjacent to the gallbladder: assessment of safety and effectiveness

PURPOSE

To assess safety and effectiveness of percutaneous image-guided cryoablation of hepatic tumors adjacent to the gallbladder.

MATERIALS AND METHODS

Twenty-one cryoablation procedures were performed to treat 19 hepatic tumors (mean size, 2.7 cm; range, 1.0-5.0 cm) adjacent to the gallbladder in 17 patients (11 male; mean age, 59.2 y; range, 40-82 y) under computed tomography (n = 15) or magnetic resonance imaging (n = 6) guidance in a retrospective study. All tumors (mean size, 2.67 cm; range, 1.0-5.0 cm) were within 1 cm (mean, 0.4 cm) of the gallbladder; seven (33%) were contiguous with the gallbladder. Primary outcomes included complication rate and severity and postprocedure gallbladder imaging findings. Secondary outcomes included technical success and technique effectiveness at 6 months.

RESULTS

Complications occurred in six of 21 procedures (29%); one (5%) was severe. Ice balls extended into the gallbladder lumen in 20 of 21 procedures (95%); no gallbladder-related complications occurred. The most common gallbladder imaging finding was mild, asymptomatic focal wall thickening after nine of 21 procedures (42%), which resolved on follow-up. Technical success was achieved in 19 of 21 sessions (90%). Six-month follow-up was available for 16 tumors; of these, all but two (87%) had no imaging evidence of local tumor progression.

CONCLUSIONS

Percutaneous cryoablation of hepatic tumors adjacent to the gallbladder can be performed safely and successfully. Although postprocedural gallbladder changes are common, they are self-limited and clinically inconsequential, even when the ice ball extends into the gallbladder lumen.

Successful percutaneous radiologic management of renal cell carcinoma tumor seeding caused by percutaneous biopsy performed before ablation

A case is reported of the successful image-based detection, diagnosis, and percutaneous ablation of tumor seeding in a 61-year-old man that was caused by percutaneous biopsy of a renal cell carcinoma performed before cryoablation and was not detected until 4 years after the biopsy procedure. Although tumor seeding is a rare complication after percutaneous biopsy or ablation, this case emphasizes the importance of imaging surveillance of the needle tract used during both biopsy and ablation procedures, provides guidance on measures that can be used to minimize the occurrence of tumor seeding, and demonstrates that entirely radiologic management can be successful.

PET/CT-guided percutaneous liver mass biopsies and ablations: targeting accuracy of a single 20 s breath-hold PET acquisition

AIM

To determine whether a single 20 s breath-hold positron-emission tomography (PET) acquisition obtained during combined PET/computed tomography (CT)-guided percutaneous liver biopsy or ablation procedures has the potential to target 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG)-avid liver masses as accurately as up to 180 s breath-hold PET acquisitions.

MATERIALS AND METHODS

This retrospective study included 10 adult patients with 13 liver masses who underwent FDG PET/CT-guided percutaneous biopsies (n = 5) or ablations (n = 5). PET was acquired as nine sequential 20 s, monitored, same-level breath-hold frames and CT was acquired in one monitored breath-hold. Twenty, 40, 60, and 180 s PET datasets were reconstructed. Two blinded readers marked tumour centres on randomized PET and CT datasets. Three-dimensional spatial localization differences between PET datasets and either 180 s PET or CT were analysed using multiple regression analyses. Statistical tests were two-sided and p < 0.05 was considered significant.

RESULTS

Targeting differences between 20 s PET and 180 s PET ranged from 0.7-20.3 mm (mean 5.3 ± 4.4 mm; median 4.3) and were not statistically different from 40 or 60 s PET (p = 0.74 and 0.91, respectively). Targeting differences between 20 s PET and CT ranged from 1.4-36 mm (mean 9.6 ± 7.1 mm; median 8.2 mm) and were not statistically different from 40, 60, or 180 s PET (p = 0.84, 0.77, and 0.35, respectively).

CONCLUSION

Single 20 s breath-hold PET acquisitions from PET/CT-guided percutaneous liver procedures have the potential to target FDG-avid liver masses with equivalent accuracy to 180 s summed, breath-hold PET acquisitions and may facilitate strategies that improve image registration and shorten procedure times.

18F-FDG positron emission tomography: potential utility in the assessment of Crohn's disease

Computed Tomography Enterography (CTE) and Magnetic Resonance Enterography (MRE) are currently the dominant imaging tests used in the assessment of patients with Crohn's disease. More recently, the possibility of utilizing F-18 fluorodeoxyglucose (18F-FDG) Positron Emission Tomography (PET) or PET/CT has been explored in several preliminary studies. 18F-FDG PET appears to enable reliable detection of moderate to severe inflammation in bowel segments involved by Crohn's disease. Perhaps more importantly, 18F-FDG PET has the potential to provide a noninvasive, quantitative measure of inflammation that dynamically reflects changes in Crohn's disease activity. If 18F-FDG PET proves useful in monitoring responses to medical therapy within a few days of therapy initiation, an important new role for imaging in the management of patients with Crohn's disease could emerge.

Estimated effective dose of CT-guided percutaneous cryoablation of liver tumors

PURPOSE

To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose.

MATERIALS AND METHODS

Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis. Using Spearman correlation coefficients, effective doses were correlated with procedural factors including number of scans, ratio of targeting distance to tumor size, anesthesia type, number of applicators, performance of ancillary procedures (hydrodissection and biopsy), and use of CT fluoroscopy.

RESULTS

Effective dose per procedure was 72±18mSv. The effective dose of targeting (37.5±12.5mSv) was the largest component compared to the effective dose of the planning phase (4.8±2.2mSv), the monitoring phase (25.5±6.8mSv), and the post-ablation survey (4.1±1.9mSv) phase (p<0.05). Effective dose correlated positively only with the number of scans (p<0.01).

CONCLUSIONS

The effective dose of CT-guided percutaneous cryoablation of liver tumors can be substantial. Reducing the number of scans during the procedure is likely to have the greatest effect on lowering dose.

Low-dose 18F-FDG PET/CT enterography: improving on CT enterography assessment of patients with Crohn disease

The purpose of this study was to evaluate the diagnostic efficacy of low-dose, combined (18)F-FDG PET/CT enterography (PET/CTE), compared with CT enterography (CTE) alone, in the assessment of patients with Crohn disease.

METHODS

Thirteen patients with Crohn disease were prospectively enrolled in this pilot study and underwent abdominal-pelvic (18)F-FDG PET/CTE using neutral oral and intravenous contrast medium. The effective dose from PET/CTE was 17.7 mSv for the first 4 patients and 8.31 mSv for the last 9 patients. Six patients underwent surgical resection of the bowel, and 7 patients underwent colonoscopy with biopsies within 27 d (mean, 12 d) of PET/CTE. PET/CTE and CTE images were each visually assessed for Crohn disease involvement in 54 bowel segments with pathology correlation. Extraintestinal findings were recorded. A CTE severity score, maximum standardized uptake value (SUVmax), SUVmax ratio, simplified endoscopic score, and clinical parameters were correlated with pathology inflammation grade, on a per-patient basis and on a per-bowel-segment basis, using Spearman correlation.

RESULTS

In 3 (23.1%) of 13 patients, (18)F-FDG uptake using PET/CTE revealed active inflammation in a bowel segment not evident using CTE (n = 2) or revealed an enterocolic fistula missed with CTE (n = 1). Visual interpretation of both PET/CTE and CTE images detected the presence of disease in all bowel segments with more than mild inflammation (sensitivity, 100%; specificity, 89.7%; positive predictive value, 78.9%; and negative predictive value, 100%). Correlation to inflammation grade per patient was the strongest for the SUVmax ratio (0.735, P = 0.004) and SUVmax (0.67, P = 0.013), as compared with the CTE score (0.62, P = 0.024). Correlation with inflammation per bowel segment was higher for the CTE score (0.79, P < 0.0001) than the SUVmax ratio (0.62, P < 0.0001) or SUVmax (0.48, P < 0.0001). SUVmax correlated strongly with serum C-reactive protein (0.82, P = 0.023), but CTE score did not.

CONCLUSION

Low-dose (18)F-FDG PET/CTE, compared with CTE, may improve the detection and grading of active inflammation in patients with Crohn disease. PET/CTE also may reveal clinically significant findings, such as enterocolic fistula, not evident on PET or CTE alone.

Multimodality non-rigid image registration for planning, targeting and monitoring during CT-guided percutaneous liver tumor cryoablation

RATIONALE AND OBJECTIVES

The aim of this study was to develop non-rigid image registration between preprocedure contrast-enhanced magnetic resonance (MR) images and intraprocedure unenhanced computed tomographic (CT) images, to enhance tumor visualization and localization during CT imaging-guided liver tumor cryoablation procedures.

MATERIALS AND METHODS

A non-rigid registration technique was evaluated with different preprocessing steps and algorithm parameters and compared to a standard rigid registration approach. The Dice similarity coefficient, target registration error, 95th-percentile Hausdorff distance, and total registration time (minutes) were compared using a two-sided Student's t test. The entire registration method was then applied during five CT imaging-guided liver cryoablation cases with the intraprocedural CT data transmitted directly from the CT scanner, with both accuracy and registration time evaluated.

RESULTS

Selected optimal parameters for registration were a section thickness of 5 mm, cropping the field of view to 66% of its original size, manual segmentation of the liver, B-spline control grid of 5 × 5 × 5, and spatial sampling of 50,000 pixels. A mean 95th-percentile Hausdorff distance of 3.3 mm (a 2.5 times improvement compared to rigid registration, P < .05), a mean Dice similarity coefficient of 0.97 (a 13% increase), and a mean target registration error of 4.1 mm (a 2.7 times reduction) were measured. During the cryoablation procedure, registration between the preprocedure MR and the planning intraprocedure CT imaging took a mean time of 10.6 minutes, MR to targeting CT image took 4 minutes, and MR to monitoring CT imaging took 4.3 minutes. Mean registration accuracy was <3.4 mm.

CONCLUSIONS

Non-rigid registration allowed improved visualization of the tumor during interventional planning, targeting, and evaluation of tumor coverage by the ice ball. Future work is focused on reducing segmentation time to make the method more clinically acceptable.

Abdominal masses sampled at PET/CT-guided percutaneous biopsy: initial experience with registration of prior PET/CT images

PURPOSE

To establish the feasibility of performing combined positron emission tomography (PET)/computed tomography (CT)-guided biopsy of abdominal masses by using previously acquired PET/CT images registered with intraprocedural CT images.

MATERIALS AND METHODS

In this HIPAA-compliant institutional review board-approved study, 14 patients underwent clinically indicated percutaneous biopsy of abdominal masses (mean size, 3.3 cm; range, 1.2-5.0 cm) in the liver (n = 6), presacral soft tissue (n = 3), retroperitoneal lymph nodes (n = 2), spleen (n = 2), and pancreas (n = 1). PET/CT images obtained no more than 62 days (mean, 18.3 days) before the biopsy procedure were registered with intraprocedural CT images by using image registration software. The registered images were used to plan the procedure and help target the masses.

RESULTS

The image registrations were technically successful in all but one patient, who had severe scoliosis. The remaining 13 biopsy procedures yielded diagnostic results, which were positive for malignancy in 10 cases and negative in three cases.

CONCLUSION

PET/CT-guided abdominal biopsy with use of prior PET/CT images registered with intraprocedural CT scans is feasible and may be helpful when fluorine 18 fluorodeoxyglucose-avid masses that are not seen sufficiently with nonenhanced CT are sampled at biopsy.

Diagnostic medical radiation dose in patients after laparoscopic bariatric surgery

BACKGROUND

The purpose of this study was to estimate the cumulative radiation dose from computed tomography (CT) scans and upper gastrointestinal fluoroscopic exams in the post-bariatric-surgery population and correlate these values with current concepts of potential radiation-induced cancer risk.

METHODS

A retrospective study of 100 roux-en-y gastric bypass (RYGB) patients and 100 gastric band patients was performed. The cumulative estimated radiation doses from CT scans and fluoroscopic studies received by these patients over a 2.5-year postoperative interval were calculated. The rate of positive radiological studies was determined. Nonlinear regression analyses were used to identify potential independent predictors of higher radiation dose.

RESULTS

Mean cumulative dose was 20 +/- 20 mSv for RYGB patients and 11 +/- 11 mSv for gastric band patients. The RYGB procedure and a higher preoperative body mass index were each significant predictors of higher cumulative radiation doses. Dose in the RYGB group ranged from 4 to 156 mSv. Dose in the gastric banding group ranged from 4 to 46 mSv. In the RYGB cohort, positive findings were present in 35% and 16% of CT and fluoroscopic studies, respectively, and 24% and 22% in the gastric band group. None of the fluoroscopic exams performed after the routine 24-h postoperative studies were positive.

CONCLUSIONS

Allowing for uncertainties of cancer risk at doses less than 50 mSv, patients undergoing laparoscopic bariatric surgery may receive radiation doses from postoperative diagnostic imaging tests that increase their lifetime cancer risk.