Magnetic resonance imaging-guided renal biopsy shows high safety and diagnostic yield: a tertiary cancer center experience.

OBJECTIVES: To evaluate the technical success and outcomes of renal biopsies performed under magnetic resonance imaging (MRI) using a closed-bore, 1.5-Tesla MRI unit. MATERIALS AND METHODS: We retrospectively reviewed our institutional biopsy database and included 150 consecutive MRI-guided biopsies for renal masses between November 2007 and March 2020. We recorded age, sex, BMI, tumor characteristics, RENAL nephrometry score, MRI scan sequence, biopsy technique, complications, diagnostic yield, pathologic outcome, and follow-up imaging. Univariate logistic regression was used to assess the association between different parameters and the development of complications. McNemar's test was used to assess the association between paired diagnostic yield measurements for fine-needle aspiration and core samples. RESULTS: A total of 150 biopsies for 150 lesions were performed in 150 patients. The median tumor size was 2.7 cm. The median BMI was 28.3. The lesions were solid, partially necrotic/cystic, and predominantly cystic in 137, eight, and five patients, respectively. Image guidance using fat saturation steady-state free precession sequence was recorded in 95% of the biopsy procedures. Samples were obtained using both fine-needle aspiration (FNA) and cores in 99 patients (66%), cores only in 40 (26%), and FNA only in three (2%). Tissue sampling was diagnostic in 144 (96%) lesions. No major complication developed following any of the biopsy procedures. The median follow-up imaging duration was 8 years and none of the patients developed biopsy-related long-term complication or tumor seeding. CONCLUSIONS: MRI-guided renal biopsy is safe and effective, with high diagnostic yield and no major complications. CLINICAL RELEVANCE STATEMENT: Image-guided renal biopsy is safe and effective, and should be included in the management algorithm of patients with renal masses. Core biopsy is recommended. KEY POINTS: • MRI-guided biopsy is a safe and effective technique for sampling of renal lesions. • MRI-guided biopsy has high diagnostic yield with no major complications. • Percutaneous image-guided biopsy plays a key role in the management of patients with renal masses.

Ablative margin quantification using deformable versus rigid image registration in colorectal liver metastasis thermal ablation: a retrospective single-center study.

PURPOSE: To investigate the correlation of minimal ablative margin (MAM) quantification using biomechanical deformable (DIR) versus intensity-based rigid image registration (RIR) with local outcomes following colorectal liver metastasis (CLM) thermal ablation. METHODS: This retrospective single-institution study included consecutive patients undergoing thermal ablation between May 2016 and October 2021. Patients who did not have intraprocedural pre- and post-ablation contrast-enhanced CT images for MAM quantification or follow-up period less than 1 year without residual tumor or local tumor progression (LTP) were excluded. DIR and RIR methods were used to quantify the MAM. The registration accuracy was compared using Dice similarity coefficient (DSC). Area under the receiver operating characteristic curve (AUC) was used to test MAM in predicting local tumor outcomes. RESULTS: A total of 72 patients (mean age 57; 44 men) with 139 tumors (mean diameter 1.5 cm ± 0.8 (SD)) were included. During a median follow-up of 29.4 months, there was one residual unablated tumor and the LTP rate was 17% (24/138). The ranges of DSC were 0.96-0.98 and 0.67-0.98 for DIR and RIR, respectively (p < 0.001). When using DIR, 27 (19%) tumors were partially or totally registered outside the liver, compared to 46 (33%) with RIR. Using DIR versus RIR, the corresponding median MAM was 4.7 mm versus 4.0 mm, respectively (p = 0.5). The AUC in predicting residual tumor and 1-year LTP for DIR versus RIR was 0.89 versus 0.72, respectively (p < 0.001). CONCLUSION: Ablative margin quantified on intra-procedural CT imaging using DIR method outperformed RIR for predicting local outcomes of CLM thermal ablation. CLINICAL RELEVANCE STATEMENT: The study supports the role of biomechanical deformable image registration as the preferred image registration method over rigid image registration for quantifying minimal ablative margins using intraprocedural contrast-enhanced CT images. KEY POINTS: • Accurate and reproducible image registration is a prerequisite for clinical application of image-based ablation confirmation methods. • When compared to intensity-based rigid image registration, biomechanical deformable image registration for minimal ablative margin quantification was more accurate for liver registration using intraprocedural contrast-enhanced CT images. • Biomechanical deformable image registration outperformed intensity-based rigid image registration for predicting local tumor outcomes following colorectal liver metastasis thermal ablation.

Effectiveness of Thermal Ablation for Renal Cell Carcinoma after Prior Partial Nephrectomy.

Background: Repeat partial nephrectomy (PN) for tumors recurring in the ipsilateral kidney is associated with surgical complexity and a higher rate of complications. Objective: To evaluate the local oncologic efficacy of thermal ablation (TA) for renal cell carcinoma (RCC) in the ipsilateral kidney following PN. Design setting participation: We included patients who underwent ablation for renal tumors in the ipsilateral kidney after PN between January 2005 and December 2019. Demographics, tumor size, procedural details, complications, pathology, local oncologic outcomes, and survival outcomes are described. Outcome measurements and statistical analysis: The procedural, pathologic, and oncologic outcomes are described. Survival rates were estimated using the Kaplan-Meier method. Results and limitations: A total of 66 patients (46 male and 20 female) with a median age of 62 yr (interquartile range [IQR] 52-69) met our inclusion criteria. In these patients, 74 TA procedures were performed for 86 lesions (median tumor size 1.9 cm, IQR 1.6-2.5). Radiofrequency ablation and cryoablation accounted for 60 (81%) and 14 (19%) procedures, respectively. Three patients (3.7%) had Clavien-Dindo grade III complications. Of 65 lesion biopsies, 62 (95.5%) were diagnostic. The most common subtype was clear cell RCC (n = 37). The median imaging follow-up duration was 60 mo (IQR 43-88). Recurrence in the ablation zone occurred for four lesions (4.6%) at a median of 6.9 mo (IQR 6.4-10.7). The rates of overall, recurrence-free, and disease-free survival were 93.1%, 94.4%, and 65.6% at 5 yr, and 71.6%, 94.4%, and 60.1% at 10 yr, respectively. Limitations include the retrospective design and the lack of a control group. Conclusions: TA is effective for the treatment of RCC in the ipsilateral kidney following PN. Patient summary: Heat treatment to remove tumor tissue is an effective option for small kidney masses recurring after partial kidney removal for cancer. Long-term follow-up data revealed that this treatment resulted in low recurrence and complication rates.

Outcomes of Radiofrequency Ablation for Solitary T1a Renal Cell Carcinoma: A 20-Year Tertiary Cancer Center Experience.

BACKGROUND: The aim is to determine the long-term oncologic and survival outcomes of the radiofrequency ablation (RFA) of solitary de novo T1a renal cell carcinoma (RCC). MATERIALS AND METHODS: We retrospectively reviewed our renal ablation registry and included only patients with new solitary, biopsy-proven T1a RCC (<4 cm) who underwent RFA from January 2001 through December 2020. We collected patient and tumor characteristics. Survival rates were estimated using the Kaplan-Meier method. RESULTS: Of the 243 patients who met our inclusion criteria (160 male and 83 female, median age 68 years), 128 (52.6%) had another primary malignancy other than renal malignancy. Two-hundred forty-three RFA procedures were performed for 243 renal tumors of a median tumor size of 2.5 cm. The median follow-up period was 3.7 years. Most tumors (68.6%) were clear cell RCC. Ten patients (4.1%) experienced Clavien-Dindo Grade III complications. Seven patients(3.1%) developed recurrence at the ablation zone, and 11 (4.5%) developed recurrence elsewhere in the kidney. The 15-year local-recurrence- and disease-free survival were 96.5% and 88.6%, respectively. The 15-year metastasis-free survival and cancer-specific survival were 100%. CONCLUSIONS: RFA is a highly effective modality for the management of T1a RCC, with low complication and recurrence rates. Long-term data revealed favorable oncologic and survival outcomes.

Temporary Reversal of Hepatoenteric Collaterals during 90Y Radioembolization Planning and Administration.

PURPOSE: This paper aims to evaluate the safety and efficacy of the temporary redirection of blood flow of hepatoenteric collaterals using a balloon catheter in the common hepatic artery (CHA) to prevent the nontarget deposition of 90Y microspheres. MATERIALS AND METHODS: In this retrospective single-center study of patients who received 90Y radioembolization (RE) from September 2010 to September 2015, diagnostic (67 patients) or treatment (72 patients) angiograms with the attempted use of a balloon catheter in the CHA to temporarily direct blood flow away from the hepatoenteric arteries were analyzed. SPECT/CT nuclear scintigraphy was performed after both diagnosis and treatment. RESULTS: Overall, only 12 hepatoenteric arteries in 11 patients required embolization due to persistent hepatoenteric flow despite the use of the balloon occlusion technique in a total of 86 patients. Physicians performed the 90Y RE using balloon occlusion with glass (n = 22) or resin (n = 50) microspheres. Over 80% administration of the prescribed 90Y dose was accomplished in 34 (67%) resin and 20 (95%) glass microsphere patients. Post-treatment 90Y RE scintigraphy confirmed the absence of extrahepatic activity in all patients. One grade 2 gastrointestinal ulcer was present after 90 days of follow-up. CONCLUSION: Temporary CHA occlusion with a balloon catheter is a reliable and reproducible alternative to the conventional coil embolization of hepatoenteric arteries during diagnostic Tc-99m macroaggregated albumin and therapeutic 90Y RE delivery.

Hepatic Abscess following Yttrium-90 Radioembolization in Patients with Surgical Bilioenteric Anastomosis or Compromised Sphincter of Oddi: A Tertiary Cancer Center Experience.

Purpose: We describe our experience with the development of hepatobiliary infection in patients with prior surgical, percutaneous, or endoscopic biliary interventions who are receiving transarterial radioembolization (TARE) with yttrium-90 (90Y) for primary or metastatic hepatobiliary lesions. Methods: Records of 15 patients with a history of prior biliary intervention and liver malignancy subsequently treated with TARE at the participating medical center from November 2009 to September 2015 were reviewed. The primary endpoint was the development of a hepatic abscess or cholangitis in a patient after radioembolization. Results: A total of 15 patients comprising 9 men and 6 women, with a median age of 49 years (range 30-73), underwent 17 TARE with 90Y procedures. Of the 15 patients, 2 (13.3%) of them developed a hepatobiliary infection. A single patient (6.6%) developed a hepatobiliary abscess. Conclusion: Our study shows a low incidence rate of hepatic abscess following TARE in patients with prior biliary intervention.

Selective Internal Radiation Therapy with Yttrium-90 for Intrahepatic Cholangiocarcinoma: A Systematic Review on Post-Treatment Dosimetry and Concomitant Chemotherapy.

Selective internal radiation therapy (SIRT) with yttrium-90 (90Y)-loaded microspheres is increasingly used for the treatment of Intrahepatic Cholangiocarcinoma (ICC). Dosimetry verifications post-treatment are required for a valid assessment of any dose-response relationship. We performed a systematic review of the literature to determine how often clinics conducted post-treatment dosimetry verification to measure the actual radiation doses delivered to the tumor and to the normal liver in patients who underwent SIRT for ICC, and also to explore the corresponding dose-response relationship. We also investigated other factors that potentially affect treatment outcomes, including the type of microspheres used and concomitant chemotherapy. Out of the final 47 studies that entered our study, only four papers included post-treatment dosimetry studies after SIRT to quantitatively assess the radiation doses delivered. No study showed that one microsphere type provided a benefit over another, one study demonstrated better imaging-based response rates associated with the use of glass-based TheraSpheres, and two studies found similar toxicity profiles for different types of microspheres. Gemcitabine and cisplatin were the most common chemotherapeutic drugs for concomitant administration with SIRT. Future studies of SIRT for ICC should include dosimetry to optimize treatment planning and post-treatment radiation dosage measurements in order to reliably predict patient responses and liver toxicity.

Gastrointestinal bleeding: imaging and interventions in cancer patients.

Gastrointestinal bleeding (GIB) among cancer patients is a major source of morbidity and mortality. Although a wide variety of etiologies contribute to GIB, special considerations should be made for cancer-related factors such as the type of malignancy, location and extent of disease, hemostatic parameters, and treatment effects. Key imaging modalities used to evaluate GIB include computed tomography angiography (CTA), radionuclide imaging, and catheter-based angiography. Understanding the cancer and treatment history and recognizing the associated imaging manifestations are important for identifying the source and potential causes of GIB in cancer patients. This article will review the common clinical presentations, causes, imaging manifestations, and angiographic management of GIB in cancer patients.

The Impact of the Use of C-Arm Cone-Beam CT During Chemoembolization for Hepatocellular Carcinoma.

OBJECTIVE: The objective of the study was to investigate the consequences of using CArm Cone-Beam computed Tomography (CBCT) on super-selective catheterization of Hepatic Artery (HA) branches during chemoembolization of hepatocellular carcinoma. METHODS: Two groups of patients were created according to the dates of their treatment sessions. Group A and Group B included patients who had their treatment sessions in 2004 - 2005 and 2008 - 2010, respectively. The sessions performed in 2006 and 2007 were excluded to allow for the adoption and incorporation of CBCT imaging into clinical practice. All chemoembolized HA branches were categorized according to selection order (0-1, 2, or ≥3). Other procedure variables were documented. RESULTS: A total of 58 and 183 sessions were included in Groups A and B, respectively, for 144 patients. C-arm CBCT was used in 2 (3%) sessions and 142 (78%) sessions in groups A and B, respectively. The average number of vessels treated was significantly higher in group B (1.8) compared to group A (1.3) (P < .0001). A shift to an increased selection order in group B (0-1, 44 [24%]; 2, 85 [46%]; ≥3, 54 [30%]) was more significant (P = .0004) than that in group A (0-1, 32 [55%]; 2, 18 [31%]; ≥3, 8 [14%]). The average duration of the procedure was significantly longer in group B (P = .0002). CONCLUSION: Using C-arm CBCT during chemoembolization has a positive impact on increasing the number and order of HA selected and chemoembolized. This comes at the expense of an increase in the duration of the procedure.

A Prospective Phase II Study of Safety and Efficacy of Sorafenib Followed by 90Y Glass Microspheres for Patients with Advanced or Metastatic Hepatocellular Carcinoma.

PURPOSE: The most common cause of death in advanced/metastatic hepatocellular carcinoma (HCC) is liver failure due to tumor progression. While retrospective studies and meta-analyses of systemic therapy combined with liver-directed therapy have been performed, prospective studies of safety/efficacy of antiangiogenesis followed by intra-arterial therapies are lacking. We tested our hypothesis that sorafenib followed by yttrium 90 glass microspheres (90Y GMs) is safe and that survival outcomes may improve by controlling hepatic tumors. METHODS: We enrolled 38 Child-Pugh A patients with advanced/metastatic HCC. In sum, 34 received sorafenib, followed after 4 weeks by 90Y GMs. Analysis of safety and survival outcomes was performed to assess adverse events, median progression-free survival, and overall survival. RESULTS: A total of 34 patients were evaluable: 14 (41.2%) with chronic hepatitis, nine (26.5%) with vascular invasion, and eleven (32.4%) with extrahepatic diseases. Safety analysis revealed that the combination therapy was well tolerated. Grade III-IV adverse events comprised fatigue (n=3), diarrhea (n=2), nausea (n=1), vomiting (n=2), hypertension (n=4), thrombocytopenia (n=1), hyperbilirubinemia (n=1), proteinuria (n=1), hyponatremia (n=1), and elevated alanine or aspartate aminotransferase (n=5). Median progression-free and overall survival were 10.4 months (95% CI 5.8-14.4) and 13.2 months (95% CI 7.9-18.9), respectively. Twelve patients (35.3%) achieved partial responses and 16 (47.0%) stable disease. Median duration of sorafenib was 20 (3-90) weeks, and average dose was 622 (466-800) mg daily. Dosimetry showed similar mean doses between planned and delivered calculations to normal liver and tumor:normal liver uptake ratio, with no significant correlation with adverse events at 3 and 6 months post-90Y treatment. CONCLUSION: This is the first prospective study to evaluate sorafenib followed by 90Y in patients with advanced HCC. The study validated our hypothesis of safety with encouraging efficacy signals of the sequencing treatment, and provides proof of concept for future combination modalities for patients with advanced or metastatic HCC. CLINICAL TRIAL REGISTRATION NUMBER: NCT01900002.

Outcomes of Percutaneous Thermal Ablation for Biopsy-Proven T1a Renal Cell Carcinoma in Patients With Other Primary Malignancies.

OBJECTIVE. The purpose of this article is to investigate the oncologic effectiveness and survival outcomes of percutaneous image-guided thermal ablation for clinical T1a renal cell carcinoma (RCC) in patients with other primary nonrenal malignancies. MATERIALS AND METHODS. We reviewed records of patients with histologically proven T1a RCC (< 4.0 cm) treated with thermal ablation over a period of 10 years between January 2005 and December 2014. We recorded past or current history of primary malignancy other than RCC, status of the primary malignancy, tumor histology (in remission or under therapy), and whether patient was currently alive or not, and if not, the date and reason of death. Three cohorts were studied: patients with RCC only (group A), patients with RCC and other primary malignancy in remission (group B), and patients with RCC and other primary malignancy under treatment (group C). The Kaplan-Meier product-limit estimator was used to estimate the survival rates. RESULTS. One hundred nine patients met the inclusion criteria (109 lesions, 110 ablation procedures). There were 46, 45, and 18 patients in the A, B, and C groups, respectively. The 5-year survival was 87%, 63%, and 40% for groups A, B, and C, respectively. The local recurrence-free survival for the whole sample was 95% at 3, 5, and 10 years. The disease-free survival was 96%, 93%, and 91% at 3, 5, and 10 years. Although a significant difference is noted between the three cohorts in overall survival (p = .02); for RCC, there were no significance differences in the local recurrence-free, disease-free, metastasis-free, and cancer-specific survivals. In addition, there was no difference in outcomes for patients in group B (in remission) when compared with those in group C (under treatment). CONCLUSION. Thermal ablation is an effective and safe modality of treatment of T1a RCC in patients with other primary malignancies that are in remission or under treatment.

Survival Outcomes for Yttrium-90 Transarterial Radioembolization With and Without Sorafenib for Unresectable Hepatocellular Carcinoma Patients.

PURPOSE: To assess the overall survival (OS) and progression-free survival (PFS) of unresectable hepatocellular carcinoma (HCC) patients undergoing yttrium-90 glass-microsphere transarterial radioembolization (TARE) with and without concurrent sorafenib. METHODS: OS and PFS were analyzed in 55 patients with an intrahepatic tumor (IHT) ≤50% without advanced or aggressive disease features (ADFs), which was referred to presence of infiltrative/ill-defined HCC, macrovascular invasion, or extrahepatic disease treated with only TARE (TARE_alone) and in 74 patients with IHT ≤50% with ADFs or IHT >50% treated with TARE and sorafenib (TARE_sorafenib). Prognostic factors for OS and PFS were identified using univariate and multivariate analyses. RESULTS: Median OS and PFS of TARE_alone patients were 21.6 (95% CI 6.1-37.1) and 9.1(95% CI 5.2-13.0) months, respectively, and for TARE_sorafenib patients 12.4 (95% CI 9.1-15.6) and 5.1 (95% CI 2.6-7.5) months, respectively. Better OS was associated with serum AFP <400 (HR 0.27, p=0.02) in TARE_alone, and IHT ≤50% (HR 0.39, p=0.004) and AFP <400 (HR 0.5, p=0.027) in TARE_sorafenib. Unilobar involvement (HR 0.43, p=0.029) and AFP <400 ng/mL (HR 0.52, p=0.015) correlated with better PFS in TARE_alone and TARE_sorafenib, respectively. Adverse events (AEs) were more frequent in TARE_sorafenib than TARE_alone (92.4 vs 80.3%), but only 9.3% were grade 3 or higher AEs. CONCLUSION: TARE_alone provided the most prominent survival benefit in IHT ≤50%-without ADF patients who had unilobar HCC and serum AFP <400 ng/mL. TARE and sorafenib yielded the best outcomes in patients with IHT ≤50% and serum AFP <400 ng/mL, with some additional grade 1-2 AEs compared to TARE only.

Blood flow diversion using the microvascular plug to avoid non target delivery of radioactive microspheres.

Temporary balloon occlusion techniques have been described to redirect blood flow during hepatic chemo- and radioembolization. A 69 years old male with pathologically proven multifocal hepatocellular carcinoma involving all the liver segments except segments 2 and 3. We temporarily occlude segment 2/3 branch with the microvascular plug (MVP) to safely deliver the Y90 glass microspheres through the multiple small segment 4 branches. Distal occlusion using MVP may provide a valuable, cheaper and readily available tool in cases of unfavorable anatomy to divert blood flow and avoid non target delivery of Chemo or Radioembolic agents.

Ablation of Small Renal Masses.

Renal cell carcinoma is most commonly diagnosed in the sixth or seventh decade of life. Historically, surgical extirpation was the gold standard treatment option for small renal masses. However, given the comorbidities in this elderly population, not all patients are candidates for surgery. The development of minimally invasive ablative therapies has solved the surgical dilemma in this patient population. Furthermore, the 2017 American Urological Association guidelines recommends consideration of percutaneous image guided thermal ablation as a treatment option for masses smaller than 3 cm even in healthy individuals. Percutaneous image guided thermal ablation is an attractive treatment option providing excellent local tumor control, fewer complications, better preservation of the renal functions, faster recovery and shorter hospital stay. Various ablative modalities are available in clinical practice. This includes radiofrequency ablation, cryoablation, microwave ablation, irreversible electroporation, high intensity focused ultrasound, and laser ablation. In this review, we focus on the most commonly used modalities including radiofrequency ablation and cryoablation and to a lesser extent microwave ablation and irreversible electroporation.

Natural History of T1N0M0 Hepatocellular Carcinoma: Large-Scale Study in the United States.

BACKGROUND: Hepatocellular carcinoma (HCC) prognosis depends on clinicopathological features in addition to the treatment provided. We aimed to assess the natural history of TNM stage I HCC tumors which received different treatment over a period of 20 years. METHODS: Between 1992 and 2011, a total of 397 stage I HCC patients were included. Detailed information was retrieved from MD Anderson Cancer Center patients' medical records. The Kaplan-Meier method was used to calculate patients' overall survival (OS). Cox regression analysis was used to calculate the estimated hazard ratio and 95% confidence interval of different prognostic factors. RESULTS: Out of 397 patients, 67.5% were males, 42.8% had hepatitis-related HCC, and 59.7% had underlying cirrhosis. After adjustment for confounding factors, we found that all therapeutic modalities were associated with a significant mortality rate reduction with an OS of 63, 42.03, 34.3, and 22.1 months among patients treated with surgery, ablation, local, and systemic therapy, respectively. A restricted analysis of cirrhotic and noncirrhotic patients showed that ablative and local therapy were significantly associated with a longer OS compared to systemic therapy. CONCLUSION: TNM stage I HCC patients have a favorable prognosis regardless of the type of treatment. Notably, ablative and local therapy significantly improved OS compared to systemic therapy.

Minimally invasive image-guided therapies for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most frequently occurring cancer globally and predominantly develops in the setting of various grades of underlying chronic liver disease, which affects management decisions. Image-guided percutaneous ablative or transarterial therapies have acquired wide acceptance in HCC management as a single treatment modality or combined with other treatment options in patients who are not amenable for surgery. Recently, such treatment modalities have also been used for bridging or downsizing before definitive treatment (ie, surgical resection or liver transplantation). This review focuses on the use of minimally invasive image-guided locoregional therapies for HCC. Additionally, it highlights recent advancements in imaging and catheter technology, embolic materials, chemotherapeutic agents, and delivery techniques; all lead to improved patient outcomes, thereby increasing the interest in these invasive techniques.

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.

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.

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.