Mohamed E. Abdelsalam

Irreversible Electroporation of the Lumbar Vertebrae in a Porcine Model: Is There Clinical-Pathologic Evidence of Neural Toxicity?

PURPOSE To evaluate the effects of irreversible electroporation (IRE) in the porcine spine. MATERIALS AND METHODS This study was approved by the institutional animal care and use committee. Twenty computed tomographically guided IRE ablations in either a transpedicular location or directly over the posterior cortex were performed in the lumbar vertebrae of 10 pigs by a single operator. T1- and T2-weighted magnetic resonance (MR) imaging was performed with and without contrast material 2 or 7 days after ablation. Mathematical modeling was performed to estimate the extent of ablation. Clinical, radiologic, pathologic, and simulation findings were analyzed. The Miller low-bias back transformation was used to construct 95% confidence intervals for the mean absolute percentage difference between the maximum length and width of the ablation zone on MR images and pathologic measurements by using square-root-transformed data. RESULTS Bipolar IRE electrode placement and ablation were successful in all cases. The mean distances from the IRE electrode to the posterior wall of the vertebral body or the exiting nerve root were 2.93 mm ± 0.77 (standard deviation) and 7.87 mm ± 1.99, respectively. None of the animals had neurologic deficits. Well-delineated areas of necrosis of bone, bone marrow, and skeletal muscle adjacent to the vertebral body were present. Histopathologic changes showed outcomes that matched with simulation-estimated ablation zones. The percentage absolute differences in the ablation measurements between MR imaging and histopathologic examination showed the following average errors: 24.2% for length and 28.8% for width measurements on T2-weighted images, and 26.1% for length and 33.3% for width measurements on T1-weighted contrast material-enhanced images. CONCLUSION IRE ablation in the porcine spine is feasible and safe and produces localized necrosis with minimal neural toxicity. Signal intensity changes on images acquired with standard MR imaging sequences demonstrate the ablation zone to be larger than that at histopathologic examination.

Pilot in vivo study of an absorbable polydioxanone vena cava filter

OBJECTIVE The objectives of this study were to evaluate tensile strength retention of polydioxanone as a function of time in a swine venous system and to assess the feasibility of an absorbable inferior vena cava (IVC) filter made from polydioxanone in a pilot swine study. METHODS Twenty strands (60 cm each) of size 1 polydioxanone absorbable suture (Ethicon, Somerville, NJ) were placed in the central venous system of domestic swine. Strands were harvested at weekly intervals during 10 weeks for tensile strength testing. Results were compared with control samples obtained from an in vitro engineered circulation system containing sodium phosphate buffer solution. Three IVC filters braided from polydioxanone suture were also catheter deployed in three swine to assess absorbable IVC filter feasibility. RESULTS Polydioxanone retained 82% tensile strength in vitro vs 79% in vivo at 35 days (P > .22), the desired prophylactic duration. For IVC filters made from polydioxanone, technical success of placement was achieved in all three filters deployed (100%). Autologous thrombus deployed inferior to the filter remained trapped in the filter until thrombus resorption, with no evidence of pulmonary emboli on follow-up computed tomography. There were no instances of caval penetration, filter-induced IVC thrombosis, filter migration, or tilt >15 degrees with imaging and clinical follow-up carried out to 32 weeks. CONCLUSIONS Strength retention of polydioxanone suture placed in the venous system of swine is similar to earlier in vitro studies out to 10 weeks (P > .06 for all weeks) and is more than sufficient (8.20 ± 0.37 kg mean load at break for size 1) to trap thrombus. Pilot animal study suggests that an absorbable polydioxanone IVC filter can be catheter deployed to capture and to hold iatrogenically administered autologous thrombus through resorption.

Percutaneous Intraportal Application of Adipose Tissue–derived Mesenchymal Stem Cells Using a Balloon Occlusion Catheter in a Porcine Model of Liver Fibrosis

PURPOSE To investigate the safety and effectiveness of a novel endovascular approach for therapeutic cell delivery using a balloon occlusion catheter in a large animal model of liver fibrosis. MATERIALS AND METHODS Transcatheter arterial embolization with ethiodized oil (Ethiodol) and ethanol was used to induce liver damage in 11 pigs. Mesenchymal stem cells (MSCs) were harvested from adipose tissue and engineered to express green fluorescent protein (GFP). A balloon occlusion catheter was positioned in the bilateral first-order portal vein branches 2 weeks after embolization to allow intraportal application of MSCs in six experimental animals. MSCs were allowed to dwell for 10 minutes using prolonged balloon inflation. Five control animals received a sham injection of normal saline in a similar fashion. Hepatic venous pressure gradient (HVPG) was measured immediately before necropsy. Specimens from all accessible lobes were obtained with ultrasound-guided percutaneous 18-gauge biopsy 2 hours after cell application. All animals were euthanized within 4 weeks. Fluorescent microscopy was used to assess the presence and distribution of cells. RESULTS Liver injury and fibrosis were successfully induced in all animals. MSCs (6-10 × 10(7)) were successfully delivered into the portal vein in the six experimental animals. Cell application was not associated with vascular complications. HVPG showed no instances of portal hypertension. GFP-expressing MSCs were visualized in biopsy specimens and were distributed primarily within the sinusoidal spaces; however, 4 weeks after implantation, MSCs could not be identified in histologic specimens. CONCLUSIONS A percutaneous endovascular approach for cell delivery using a balloon occlusion catheter proved safe for intraportal MSC application in a large animal model of liver fibrosis.

JOURNAL CLUB: Standardizing CT-Guided Biopsy Procedures: Patient Dose and Image Noise

OBJECTIVE The objective of this study was to standardize our image acquisition protocol for CT-guided biopsy procedures. MATERIALS AND METHODS The records of consecutive patients who underwent CT-guided biopsy 3 months before (n = 598 biopsies) and 3 months after (n = 540 biopsies) standardization of our image acquisition protocol were retrospectively reviewed. CT technical parameters were individualized on the basis of the sum of the anteroposterior and transverse dimensions of the patient. Information on patient demographic characteristics, biopsy site, complications associated with the procedure, and diagnostic yield was collected. The radiation dose metrics that were evaluated included the volume CT dose index, dose-length product, and size-specific dose estimate. Image noise was quantified using the SD of the CT number measured in subcutaneous fat. Fisher exact test and one-way ANOVA were used to evaluate statistical significance. RESULTS The mean dose-length product decreased by 72.3% (from 699.7 to 193.9 mGy × cm; p < 0.0001), and statistically significant decreases in dose-length product were observed when data were stratified according to biopsy site (i.e., lung, solid organ, lymph node, or bone; for all sites, p < 0.0001). The mean size-specific dose estimate decreased by 58.9% (from 125 to 51.4 mGy), which was statistically significant (p < 0.001). Image noise increased during the study period, but this increase was not statistically significantly different among the four biopsy sites (p = 0.46). CONCLUSION Standardization of the image acquisition protocol used in CT-guided biopsy procedures significantly reduced patient radiation dose and decreased variability in image noise.

Standardizing CT-guided biopsy procedures: Patient dose and image noise

OBJECTIVE The objective of this study was to standardize our image acquisition protocol for CT-guided biopsy procedures. MATERIALS AND METHODS The records of consecutive patients who underwent CT-guided biopsy 3 months before (n = 598 biopsies) and 3 months after (n = 540 biopsies) standardization of our image acquisition protocol were retrospectively reviewed. CT technical parameters were individualized on the basis of the sum of the anteroposterior and transverse dimensions of the patient. Information on patient demographic characteristics, biopsy site, complications associated with the procedure, and diagnostic yield was collected. The radiation dose metrics that were evaluated included the volume CT dose index, dose-length product, and size-specific dose estimate. Image noise was quantified using the SD of the CT number measured in subcutaneous fat. Fisher exact test and one-way ANOVA were used to evaluate statistical significance. RESULTS The mean dose-length product decreased by 72.3% (from 699.7 to 193.9 mGy × cm; p < 0.0001), and statistically significant decreases in dose-length product were observed when data were stratified according to biopsy site (i.e., lung, solid organ, lymph node, or bone; for all sites, p < 0.0001). The mean size-specific dose estimate decreased by 58.9% (from 125 to 51.4 mGy), which was statistically significant (p < 0.001). Image noise increased during the study period, but this increase was not statistically significantly different among the four biopsy sites (p = 0.46). CONCLUSION Standardization of the image acquisition protocol used in CT-guided biopsy procedures significantly reduced patient radiation dose and decreased variability in image noise.

Incidental renal tumors in cancer survivors: Minimally invasive management by image-guided thermal ablation.

258 Background: To investigate presentation, management and outcome of renal tumors in patients with prior or current history of cancer. METHODS A retrospective review of a database for patients undergoing ablation of renal tumors between January 2012 and June 2014 was performed. For each patient , the following was recorded: Prior or current history of cancer (other than renal cell carcinoma), histology of primary tumor, status of primary cancer (remission or under therapy), size of the renal tumor, thermal ablation technology , complications of ablation, development of metastases from renal tumor, deceased or alive , cause of death and the length of follow up. RESULTS Ninety five renal ablation procedures were performed in 91 patients between January 2012 and June 2014. Of this subset, 37 patients (27 male and 10 females) with average age 63 years (Age range 53-85 Years) had prior or current history of malignancy (6 patients had more than one primary cancer) other than renal tumor including Prostate(6), colorectal (4), Breast (4) lymphoma (3) and others (20). All renal tumors were discovered incidentally, none of the patients had symptoms related to renal tumors. Twenty four patients were in remission and 13 patients were undergoing therapy for their primary malignancy at the time of ablation. Ablation was performed using radiofrequency (n = 30) or cryoablation (n = 9) for 39 renal lesions with average size of 2.4cm (Range 1.1 to 4 cm). After average of 20 months (range 5-35 months) of observation 34 patients (92%) were still alive. Three patients died of their primary cancer. None of the patients developed complication from the procedure, 1 patient had recurrence after 6 month; for which renal ablation was performed. None of the patients developed metastatic disease from or died of renal cell carcinoma. CONCLUSIONS Staging workup and surveillance imaging studies in cancer patients can lead to incidental detection of primary renal tumors. Minimally invasive therapy with image guided radiofrequency ablation or cryotherapy is feasible, safe and effective. Image guided ablation has no discernable impact on the course of therapy for the primary tumor. Furthermore, it has minimal to no morbidity for patients in remission.

Standardizing CT-guided biopsy procedures

OBJECTIVE The objective of this study was to standardize our image acquisition protocol for CT-guided biopsy procedures. MATERIALS AND METHODS The records of consecutive patients who underwent CT-guided biopsy 3 months before (n = 598 biopsies) and 3 months after (n = 540 biopsies) standardization of our image acquisition protocol were retrospectively reviewed. CT technical parameters were individualized on the basis of the sum of the anteroposterior and transverse dimensions of the patient. Information on patient demographic characteristics, biopsy site, complications associated with the procedure, and diagnostic yield was collected. The radiation dose metrics that were evaluated included the volume CT dose index, dose-length product, and size-specific dose estimate. Image noise was quantified using the SD of the CT number measured in subcutaneous fat. Fisher exact test and one-way ANOVA were used to evaluate statistical significance. RESULTS The mean dose-length product decreased by 72.3% (from 699.7 to 193.9 mGy × cm; p < 0.0001), and statistically significant decreases in dose-length product were observed when data were stratified according to biopsy site (i.e., lung, solid organ, lymph node, or bone; for all sites, p < 0.0001). The mean size-specific dose estimate decreased by 58.9% (from 125 to 51.4 mGy), which was statistically significant (p < 0.001). Image noise increased during the study period, but this increase was not statistically significantly different among the four biopsy sites (p = 0.46). CONCLUSION Standardization of the image acquisition protocol used in CT-guided biopsy procedures significantly reduced patient radiation dose and decreased variability in image noise.