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To evaluate the efficacy of percutaneous biopsy for diagnosing intrahepatic cholangiocarcinoma (IHCCA). Retrospective review of biopsy and pathology databases from 2006 to 2019 yielded 112 patients (54F/58 M; mean age, 62.9 years; 27 cirrhotic) with IHCCA who underwent percutaneous biopsy. Data regarding the lesion, biopsy procedure technique, and diagnostic yield were collected. If biopsy was non-diagnostic or discordant with imaging, details of repeat biopsy or resection/explant were gathered. A control group of 100 consecutive patients (56F/44 M; mean age, 63 years, 5 cirrhotic) with focal liver lesions > 1 cm was similarly assessed. Mean IHCCA lesion size was 6.1 ± 3.6 cm, with dominant lesion sampled in 78% (vs. satellite in 22%). 95% (n = 106) were US guided and 96% were core biopsies (n = 108), typically 18G (n = 102, 91%), median 2 passes. 18 patients (16%) had discordant/ambiguous pathology results requiring repeat biopsy, with two patients requiring 3–4 total attempts. A 4.4% minor complication rate was seen. Mean time from initial biopsy to final diagnosis was 60 ± 120 days. Control group had mean lesion size of 2.9 ± 2.5 cm and showed a non-diagnostic rate of 3.3%, both significantly lower than that seen with CCA, with average time to diagnosis of 21 ± 28.8 days (p = 0.002, p = 0.001). IHCCA is associated with lower diagnostic yield at initial percutaneous biopsy, despite larger target lesion size. If a suspicious lesion yields a biopsy result discordant with imaging, the radiologist should recommend prompt repeat biopsy to prevent delay in diagnosis.

Microwave (MW) ablation and stereotactic body radiation therapy (SBRT) have potentially complementary advantages and limitations for treating inoperable renal cell carcinoma (RCC). Combining SBRT and MWA may optimize tumor control and toxicity for patients with larger (>5 cm) RCCs or those with vascular involvement. We retrospectively reviewed patients at our institution with RCC treated between 2014 – 2018 to identify patients treated with a combination of SBRT and MW ablation. Seven patients with RCC were treated with combination of SBRT and MW ablation, median tumor size of 6.4 cm. Local control was 100% with a median follow-up of 15 months. Four patients experienced grade 2 nausea during SBRT. Three patients experienced toxicities after MW ablation, two with grade 1 hematuria and one with grade 3 retroperitoneal bleed/collecting system injury. Median eGFR preceding and following SBRT and MW ablation was 69 mL/min/1.73m2 and 68 mL/min/1.73m2 (p=0.19) respectively. In patients who are not surgical candidates, larger RCCs or those with vascular invasion are challenging to treat. Combination treatment with SBRT and MW ablation may balance the risks and benefits of both therapies and demonstrates high local control in our series. MW ablation and SBRT have potentially complementary advantages and limitations.

Liver cancer is a leading cause of cancer related deaths, however primary treatment options such as surgical resection and liver transplants may not be viable for many patients. Minimally invasive image-guided microwave ablation (MWA) provides a locally effective treatment option for these patients with an impact comparable to surgery for both cancer specific and overall survival. MWA efficacy is correlated with accurate image guidance, however conventional modalities such as B-mode ultrasound and computed tomography (CT) have limitations. Alternatively, ultrasound elastography has been utilized to demarcate post-ablation zones yet has limitations for pre-ablation visualization due to variability in strain contrast between cancer types. This study attempts to characterize both pre-ablation tumors and post-ablation zones using electrode displacement elastography (EDE) for 13 patients with hepatocellular carcinoma or liver metastasis. Typically, MWA ablation margins of 0.5 – 1.0 cm are desired, which are strongly correlated with treatment efficacy. Our results demonstrate an average estimated ablation margin inner quartile range of 0.54 – 1.21 cm with a median value of 0.84 cm. These treatment margins lie within or above the targeted ablative margin indicating the potential for using EDE for differentiating index tumors and ablated zones for use during clinical ablations. We also obtained a high correlation between corresponding segmented cross-sectional areas from contrast-enhanced computed tomography (CECT), the current clinical gold standard, when compared to EDE strain images with r(2) values of 0.97 and 0.98 for pre- and post-ablation regions.

To compare the diagnostic accuracy of generalist radiologists working in a community setting against abdominal radiologists working in an academic setting for the interpretation of MR when diagnosing acute appendicitis among emergency department patients. This observational study examined MR image interpretation (non-contrast MR with diffusion-weighted imaging and intravenous contrast-enhanced MR) from a prospectively enrolled cohort at an academic hospital over 18 months. Eligible patients had an abdominopelvic CT ordered to evaluate for appendicitis and were > 11 years old. The reference standard was a combination of surgery and pathology results, phone follow-up, and chart review. Six radiologists blinded to clinical information, three each from community and academic practices, independently interpreted MR and CT images in random order. We calculated test characteristics for both individual and group (consensus) diagnostic accuracy then performed Chi-square tests to identify any differences between the subgroups. Analysis included 198 patients (114 women) with a mean age of 31.6 years and an appendicitis prevalence of 32.3%. For generalist radiologists, the sensitivity and specificity (95% confidence interval) were 93.8% (84.6–98.0%) and 88.8% (82.2–93.2%) for MR and 96.9% (88.7–99.8%) and 91.8% (85.8–95.5%) for CT. For fellowship-trained radiologists, the sensitivity and specificity were 96.9% (88.2–99.5%) and 89.6% (82.8–94%) for MR and 98.4% (90.5–99.9%) and 93.3% (87.3–96.7%) for CT. No statistically significant differences were detected between radiologist groups (p = 1.0, p = 0.53, respectively) or when comparing MR to CT (p = 0.21, p = 0.17, respectively). MR is a reliable, radiation-free imaging alternative to CT for the evaluation of appendicitis in community-based generalist radiology practices. • There was no significant difference in MR image interpretation accuracy between generalist and abdominal fellowship-trained radiologists when evaluating sensitivity (p = 1.0) and specificity (p = 0.53). • There was no significant difference in accuracy comparing MR to CT imaging for diagnosing appendicitis for either sensitivity (p = 0.21) or specificity (p = 0.17). • With experience, generalist radiologists enhanced their MR interpretation accuracy as demonstrated by improved interpretation sensitivity (OR 2.89 CI 1.44-5.77, p = 0.003) and decreased mean interpretation time (5 to 3.89 min).

Management options for small renal masses include active surveillance, partial nephrectomy, radical nephrectomy, and thermal ablation. For tumors typically ≤3 cm in size, thermal ablation is a good option for those desiring an alternative to surgery or active surveillance, especially in patients who are considered high surgical risk. We favor microwave ablation because of the more rapid heating, higher temperatures that overcome the heat sink effect of vessels, reproducible cell kill, and a highly visible ablation zone formed by water vapor that corresponds well to the zone of necrosis. For central tumors, we favor cryoablation because of the slower formation of the ablation zone and less likelihood of damage to the collecting system. With microwaves, it is important to monitor the ablation zone in real time (ultrasound is the best modality for this purpose), avoid direct punctures of the collecting system, and to place probes tangential to the collecting system to avoid burning open a persistent tract between the urothelium and extrarenal spaces or causing strictures. The surgical steps described in this video cover our use of high-frequency jet ventilation with general anesthesia to minimize organ motion, initial imaging and targeting, probe insertion, hydrodissection (a technique that enables displacement of adjacent structures), the ablation itself, and finally our dressing. Postoperative cares typically consist of observation with a same-day discharge or an overnight stay. Follow-up includes a magnetic resonance imaging abdomen with and without contrast, chest X-ray, and laboratories (basic metabolic panel, complete blood count, and C-reactive protein) 6 months postablation. Overall, percutaneous microwave ablation is an effective and safe treatment option for renal cell carcinoma in both T1a and T1b tumors in selected patients with multiple studies showing excellent oncologic outcomes when compared with partial and radical nephrectomy.

We present a case report that shows an abscopal effect in the context of a safety and efficacy clinical trial for histotripsy as ablation technique in liver tumors. The abscopal effect appears in the form of reduction in the volume of nontreated tumor lesions in the same organ, as well as sustained reduction of tumor marker [carcinoembryonic antigen (CEA)] that extends weeks away of the procedure. Histotripsy is a novel noninvasive, nonthermal, and nonionizing precise ablation technique for tissue destruction guided by ultrasonography. We discuss the feasibility of this technique compared with other focal therapies and its possibilities as immune system enhancer.

To evaluate the impact of anterior tumor location on oncologic efficacy, complication rates, and procedure duration for 151 consecutive biopsy-proven clinical T1a renal cell carcinoma (RCC) treated with percutaneous microwave (MW) ablation. This single-center retrospective study was performed under a waiver of informed consent. One hundred forty-eight consecutive patients (103 M/45 F; median age 67 years, IQR 61–73) with 151 cT1a biopsy-proven RCC (median diameter 2.4 cm, IQR 1.9–3.0) were treated with percutaneous MW ablation between March 2011 and August 2017. Patient and procedural data collected included Charlson comorbidity index (CCI), RENAL nephrometry score (NS), use of hydrodisplacement, MW antennas/generator output/time, and procedure time (PT). Data were stratified by anterior, posterior, and midline tumor location and compared with the Kruskal–Wallis or chi-squared tests. The Kaplan–Meier method was used for survival analyses. Tumor size, NS, and use/volume of hydrodisplacement were similar for posterior and anterior tumors (p > 0.05). Patients with anterior tumors had a higher CCI (3 vs 4, p = 0.001). Median PT for posterior and anterior tumors was similar (100 vs 108 min, p = 0.26). Single session technical success and primary efficacy were achieved for all 151 tumors including 61 posterior and 67 anterior tumors. The 4 (3%) Clavien III–IV complications and 6 (4%) local recurrences were not associated with tumor location (p > 0.05). Three-year RFS, CSS, and OS were 95% (95% CI 0.87, 0.98), 100% (95% CI 1.0, 1.0), and 96% (95% CI 0.89, 0.98), respectively. The safety and efficacy of percutaneous microwave ablation for anterior and posterior RCC are similar. • The safety profile for percutaneous microwave ablation of anterior and posterior T1a renal cell carcinoma is equivalent. • Percutaneous microwave ablation of T1a renal cell carcinoma provides durable oncologic control regardless of tumor location. • Placement of additional microwave antennas and use of hydrodisplacement are associated with longer procedure times.

BACKGROUND Computed tomography (CT) is commonly used in the Emergency Department (ED) to evaluate patients with abdominal pain, but exposes them to ionizing radiation, a possible carcinogen. MRI does not utilize ionizing radiation and may be an alternative. PURPOSE To compare the sensitivity of MRI and CT for acute abdominopelvic ED diagnoses. STUDY TYPE Prospective, observational cohort. POPULATION ED patients ≥12 years old and undergoing CT for possible appendicitis. FIELD STRENGTH/SEQUENCE 1.5 T MRI, including T1 -weighted, T2 -weighted, and diffusion-weighted imaging sequences. ASSESSMENT Three radiologists independently interpreted each MRI and CT image set separately and blindly, using a standard case report form. Assessments included likelihood of appendicitis, presence of an alternative diagnosis, and likelihood that the alternative diagnosis was causing the patient's symptoms. An expert panel utilized chart review and follow-up phone interviews to determine all final diagnoses. Times to complete image acquisition and image interpretation were also calculated. STATISTICAL TESTS Sensitivity was calculated for each radiologist and by consensus (≥2 radiologists in agreement) and are reported as point estimates with 95% confidence intervals. Two-sided hypothesis tests comparing the sensitivities of the three image types were conducted using Pearson's chi-squared test with the traditional significance level of P = 0.05. RESULTS There were 15 different acute diagnoses identified on the CT/MR images of 113 patients. Using individual radiologist interpretations, the sensitivities of noncontrast-enhanced MRI (NCE-MR), contrast-enhanced MR (CE-MR), and CT for any acute diagnosis were 77.0% (72.6-81.4%), 84.2% (80.4-88.0%), and 88.7% (85.5-92.1%). Sensitivity of consensus reads was 82.0% (74.9-88.9%), 87.1% (81.0-93.2%), 92.2% (87.3-97.1%), respectively. There was no difference in sensitivities between CE-MR and CT by individual (P = 0.096) or consensus interpretations (P = 0.281), although NCE-MR was inferior to CT in both modes of analysis (P

Histotripsy is a novel noninvasive nonthermal, nonionizing, and precise treatment technique for tissue destruction. Contrast-enhanced ultrasound (CEUS) improves the detection, characterization, and follow-up of hepatic lesions because it depicts accurately the vascular perfusion of both normal hepatic tissue and hepatic tumors. We present the spectrum of imaging findings of CEUS after histotripsy treatment of hepatic tumors. CEUS provides real-time information, a close approximation to the dimension of the lesion, and a clear definition of its margins. Hepatic tumors detected by ultrasound can be potentially treated using B-mode ultrasound-guided histotripsy and characterized and monitored with CEUS. CEUS has shown to be very useful after tissue treatment to monitor and assess the evolution of the treated zone. Histotripsy treated zones are practically isoechogenic and slightly heterogeneous, and their limits are difficult to establish using standard B-mode ultrasound. The use of CEUS after histotripsy showing uptake of contrast protruding into the treated zone is clinically relevant to identify residual tumors and establish the most appropriate management strategy avoiding unnecessary treatments. We here describe CEUS findings after histotripsy for hepatic tumors.

Primary liver cancers and liver metastases are malignancies resulting in high mortality rates [1, 2]. As a treatment method, microwave ablation (MWA) presents with treatment success similar to surgical resection while significantly reducing morbidity and mortality for patients, requiring ablative margins of 0.5 – 1.0 cm verified using medical imaging. Unfortunately, traditional imaging modalities used namely, contrast enhanced computed tomography and B-mode ultrasound have limitations in providing visualization for validating MWA efficacy. Alternatively, electrode displacement elastography (EDE) has shown potential in visualizing MWA post ablation regions. However, EDE has not been used previously for comparing the pre and post ablation cross-sectional area measurements for ablative margin estimation and treatment of liver cancers. This work shows that EDE can achieve ablative margin estimation by comparing pre- and post- ablation EDE strain imaging for use in determining MWA efficacy.

We sought to determine if vertebral trabecular attenuation values measured on routine body computed tomography (CT) scans obtained for a variety of unrelated indications can predict future osteoporotic fractures at multiple skeletal sites. For this Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved retrospective cohort study, trabecular attenuation of the first lumbar vertebra was measured in 1966 consecutive older adults who underwent chest and/or abdominal CT at a single institution over the course of 1 year. New pathologic fragility fractures that occurred after a patient's CT study date were identified through an electronic health record database query using International Classification of Diseases (ICD)-9 codes for vertebral, hip, and extremity fractures. Univariate and multivariate Cox proportional hazards regression were performed to determine the effect of L1 trabecular attenuation on fracture-free survival. Age at CT, sex, and presence of a prior fragility fracture were included as confounders in multivariate survival analysis. Model discriminative capability was assessed through calculation of an optimism-corrected concordance index. A total of 507 patients (mean age 73.4 ± 6.3 years; 277 women, 230 men) were included in the final analysis. The median post-CT follow-up interval was 5.8 years (interquartile range 2.1-11.0 years). Univariate analysis showed that L1 attenuation values ≤90 Hounsfield units (HU) are significantly associated with decreased fracture-free survival (p < 0.001 by log-rank test). After adjusting for age, sex, prior fracture, glucocorticoid use, bisphosphonate use, chronic kidney disease, tobacco use, ethanol abuse, cancer history, and rheumatoid arthritis history, multivariate analysis demonstrated a persistent modest effect of L1 attenuation on fracture-free survival (hazard ratio [HR] = 0.63 per 10-unit increase; 95% confidence interval [CI] 0.47-0.85). The model concordance index was 0.700. Ten-year probabilities for major osteoporosis-related fractures straddled the treatment threshold for most subcohorts over the observed L1 HU range. In conclusion, for patients undergoing body CT scanning for any indication, L1 vertebral trabecular attenuation is a simple measure that, when ≤90 HU, identifies patients with a significant decrease in fracture-free survival. © 2018 American Society for Bone and Mineral Research.

We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average. With EDE, the ablated region was delineable on 40 patients on average, with less imaging depth dependence. Study of tissue-mimicking phantoms revealed that the ablation region dimensions measured on EDE and ARFI images were within 8%, whereas the image contrast and contrast-to-noise ratio with EDE was two to three times higher than that obtained with ARFI. This study indicated that EDE provided improved monitoring results for minimally invasive MWA in clinical procedures for liver cancer and metastases.

We assessed the initial clinical performance and third-party reimbursement rates of supplementary computer-aided detection (CAD) at CT colonography (CTC) for detecting colorectal polyps 6 mm or larger in routine clinical practice.We retrospectively assessed the prospective clinical performance of a U.S. Food and Drug Administration-approved CAD system in second-reader mode in 347 consecutive adults (mean age, 57.6 years; 205 women, 142 men) undergoing CTC evaluation over a 5-month period. The reference standard consisted of the prospective interpretation by experienced CTC radiologists combined with subsequent optical colonoscopy (OC), if performed. We also assessed third-party reimbursement for CAD for studies performed over an 18-month period.In all, 69 patients (mean [± SD] age, 59.0 ± 7.7 years; 32 men, 37 women) had 129 polyps ≥ 6 mm. Per-patient CAD sensitivity was 91.3% (63 of 69). Per-polyp CAD-alone sensitivity was 88.4% (114 of 129), including 88.3% (83 of 94) for 6- to 9-mm polyps and 88.6% (31 of 35) for polyps 10 mm or larger. On retrospective review, three additional polyps 6 mm or larger were seen at OC and marked by CAD but dismissed as CAD false-positives at CTC. The mean number of false-positive CAD marks was 4.4 ± 3.1 per series. Of 1225 CTC cases reviewed for reimbursement, 31.0% of the total charges for CAD interpretation had been recovered from a variety of third-party payers.In our routine clinical practice, CAD showed good sensitivity for detecting colorectal polyps 6 mm or larger, with an acceptable number of false-positive marks. Importantly, CAD is already being reimbursed by some third-party payers in our clinical CTC practice.

The purpose of this study was to evaluate patient, tumor and technical factors associated with procedural complications and nondiagnostic findings following percutaneous core renal mass biopsy.We reviewed core renal mass biopsies from 2000 to 2017. Complications at 30 days or less were graded using the Clavien-Dindo system. Univariate and multivariable analyses were done to evaluate associations between clinical characteristics and the risk of complications or nondiagnostic findings.Of the 1,155 biopsies performed in a total of 965 patients procedural complications were identified in 24 patients (2.2%), including 5 (0.4%) with major complications (Clavien 3a or greater). No patients were identified with tumor seeding of the biopsy tract. Patient age, body mass index, gender, Charlson comorbidity index, smoking, mass diameter, nephrometry score, number of cores and prior biopsy were not associated with complication risk (p = 0.06 to 0.53). Complications were not increased for patients on aspirin or those with low platelets (25,000 to 160,000/μl blood) or a mildly elevated INR (international normalized ratio) (1.2 to 2.0, p = 0.16, 0.07 and 0.50, respectively). The complication risk was not increased during the initial 50 cases of a radiologist or when a trainee was present (p = 0.35 and 0.12, respectively). Nondiagnostic findings were present in 14.6% of biopsies. Independent predictors included cystic features, contrast enhancement, mass diameter and skin-to-mass distance (p0.001, 0.002, 0.02 and 0.049, respectively). Radiologist experience was not associated with the nondiagnostic rate (p = 0.23). Prior nondiagnostic biopsy was not associated with an increased nondiagnostic rate on subsequent attempts (19.2% vs 14.2%, p = 0.23).Procedural complications following biopsy are rare even with low serum platelets, a mildly elevated INR or when the patient remains on aspirin. Cystic features, hypo-enhancement on imaging, a smaller mass diameter and a longer skin-to-tumor distance increase the risk of nondiagnostic findings.

Intraoperative ultrasound (IOUS) is a valuable adjunctive tool that can provide real-time diagnostic information in surgery that has the potential to alter patient management and decrease complications. Lesion localization, characterization and staging can be performed, as well as surveying for additional lesions and metastatic disease. IOUS is commonly used in the liver for hepatic metastatic disease and hepatocellular carcinoma, in the pancreas for neuroendocrine tumors, and in the kidney for renal cell carcinoma. IOUS allows real-time evaluation of vascular patency and perfusion in organ transplantation and allows for early intervention for anastomotic complications. It can also be used to guide intraoperative procedures such as biopsy, fiducial placement, radiation, or ablation. A variety of adjuncts including microbubble contrast and elastography may provide additional information at IOUS. It is important for the radiologist to be familiar with the available equipment, common clinical indications, technique, relevant anatomy and intraoperative imaging appearance to optimize performance of this valuable imaging modality.

For patients undergoing routine contrast-enhanced CT examinations, an opportunity exists for concurrent osteoporosis screening without additional radiation exposure or patient time using proximal femur CT X-ray absorptiometry (CTXA). We investigated the effect of i.v. contrast enhancement on femoral neck CTXA T-score measurement compared with DXA. This cohort included 355 adults (277 female; mean age, 59.7 ± 13.3 years; range, 21 to 90 years) who underwent standard contrast-enhanced CT assessment at 120 kVp over an 8-year interval, as well as DXA BMD assessment within 100 days of the CT study (mean 46 ± 30 days). Linear regression and a Bland-Altman plot were performed to compare DXA and CTXA results. CTXA diagnostic sensitivity and specificity was evaluated with DXA as the reference standard. There was good correlation between DXA and CTXA (r2 = 0.824 for both areal BMD and T-scores) and the SD of the distribution of residuals was 0.063 g/cm2 or 0.45 T-score units. There was no trend in differences between the two measurements and a small bias was noted with DXA T-score +0.18 units higher than CTXA. CTXA had a sensitivity for discriminating normal from low bone mineral density of 94.9% (95% CI, 90.6% to 97.4%). For opportunistic osteoporosis screening at routine post-contrast abdominopelvic CT scans, CTXA produces T-scores similar to DXA. Because femoral neck CTXA BMD measurement is now included in the WHO Fracture Risk Assessment Tool (FRAX) tool, this opportunistic method could help to increase osteoporosis screening because it can be applied regardless of the clinical indication for CT scanning. © 2016 American Society for Bone and Mineral Research.

Microwave (MW) ablation was used to treat 12 hepatocellular adenomas in six patients (five women and one man; mean age, 39.6 y). Mean treated tumor size was 2.7 cm ± 2.0. Tumor response was evaluated with serial cross-sectional imaging for a mean follow-up of 12.6 months ± 7.1. Primary treatment effectiveness and local tumor control were 100%. There were no instances of hemorrhage, malignant transformation, new hepatic tumors, or extrahepatic metastases. This early experience of treatment of hepatic adenomas by MW ablation demonstrates it to be a safe and feasible treatment modality at short-term follow-up. Continued investigation, including comparison with other treatment modalities, is warranted.

OBJECTIVE The aim of this study was to compare the liver segmental volume ratio (LSVR), a novel volumetric computed tomography measurement, with established linear measurements for differentiating normal from cirrhotic livers. METHODS Hepatic volumes were measured using semiautomated software (Liver Analysis Application, Philips IntelliSpace Portal) on contrast-enhanced abdominal computed tomography scans in 312 adults, including 108 patients with end-stage liver disease (mean age, 55 years; 63 men/45 women) and 204 healthy controls (potential renal donors; mean age, 46 years; 82 men/122 women). The LSVR was defined as the volume ratio of Couinaud segments I to III to segments IV to VIII. Linear measures included the caudate-to-right lobe ratio and maximal splenic dimension. RESULTS Differences in LSVR between cirrhotics and controls were highly significant (P < 0.0001; mean, 0.55 ± 0.29 versus 0.27 ± 0.07; receiver operating characteristic [ROC] area under the curve [AUC], 0.916). Linear caudate-to-right lobe ratio differences were not statistically significant between the 2 cohorts (P = 0.051; ROC AUC, 0.567). Total liver volume was ineffective for discrimination (ROC AUC, 0.598). An LSVR threshold of 0.35 or greater had a sensitivity and specificity for cirrhosis of 81.5% and 88.7%, respectively. CONCLUSIONS Regional hepatic volume changes, as reflected by the LSVR, are more effective than standard linear measures or total liver volume for differentiating cirrhotic from normal livers.

The risk of electromagnetic interference between microwave (MW) ablation and cardiac implantable electronic devices (CIEDs), ie, pacemakers and defibrillators, has not been fully evaluated. Fourteen MW ablations (kidney, n = 8; liver, n = 5; lung, n = 1) were performed in 13 patients with CIEDs in normal operating mode. Electrocardiography tracings, cardiovascular complications, tumor size, tumor-to-CIED distance, and tumor-to-device lead distance were recorded. Mean tumor size was 2.9 cm, mean tumor-to-CIED distance was 26.4 cm (range, 9–30 cm), and mean tumor-to-lead distance was 12.1 cm (range, 3.5–20 cm). No device-based cardiovascular complications or class C or higher complications per Society of Interventional Radiology criteria were identified. MW ablation appears to be safe in select patients with CIEDs.

Tumor ablation in the liver has evolved to become a well-accepted tool in the management of increasing complex oncologic patients. At present, percutaneous ablation is considered first-line therapy for very early and early hepatocellular carcinoma and second-line therapy for colorectal carcinoma liver metastasis. Because thermal ablation is a treatment option for other primary and secondary liver tumors, an understanding of the underlying tumor biology is important when weighing the potential benefits of ablation. This article reviews ablation modalities, indications, patient selection, and imaging surveillance, and emphasizes technique-specific considerations for the performance of percutaneous ablation.

OBJECTIVE. The purpose of this study was to evaluate the incidence of clinically significant diaphragmatic injuries and local tumor progression after microwave ablation of hepatic tumors abutting the diaphragm. MATERIALS AND METHODS. This retrospective study included 55 peripheral hepatic tumors abutting the diaphragm treated by microwave ablation versus a control group of 15 centrally located tumors. Treated tumors were further subdivided according to the use of artificial ascites (fluid vs no fluid) and whether instilled fluid achieved displacement of the liver surface away from the diaphragm (displaced vs nondisplaced). Measurements of tumor size, distance to the diaphragm, ablation zone size, displacement distance, length of the ablation zone along the liver capsule, diaphragm thickness, diaphragmatic hernia, and local tumor progression were made on pre- and postablation CT and MRI. The electronic medical record was reviewed for patient self-reported pain scores and other symptoms. Data were analyzed by use of the Kruskal-Wallis and Fisher exact tests. RESULTS. There were no cases of diaphragmatic hernia in peripheral or central tumors. Postablation diaphragm thickness was higher in peripheral hepatic tumors than in control tumors. Peripheral tumors had an overall higher incidence of postprocedure shoulder pain (18% vs 0%) and local tumor progression (5.5% vs 0%) compared with control tumors, but these differences did not achieve statistical significance (p = 0.2 and p = 1, respectively). CONCLUSION. Our study shows that microwave ablation of peridiaphragmatic hepatic tumors is safe, without incidence of diaphragmatic hernia, and can be performed with a low rate of local tumor progression.

An effective imaging modality to delineate the ablated region after microwave ablation (MWA) therapy is crucial to yield promising treatment outcomes. Ultrasound B mode imaging is widely used to guide the ablation needle. However, the image quality suffers from relatively low imaging contrast due to the similar echogenicity between the ablated and surrounding liver tissue. In this study, we applied a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), to delineate the thermally ablated regions for patients diagnosed with hepatocellular carcinoma (HCC) treated with MWA procedures.

An effective imaging modality to delineate ablated regions after microwave ablation (MWA) therapy is crucial to yield successful treatment outcomes. Ultrasound B-mode imaging is widely used to guide the ablation antenna placement. However, the image quality suffers from relatively low imaging contrast due to the similar echogenicity between the ablated and surrounding tissue. In this study, we applied a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), to delineate the thermally ablated regions for patients diagnosed with hepatocellular carcinoma (HCC) and treated with minimally invasive MWA procedures. Under our approved institutional review board (IRB) protocol, EDE was used for monitoring MWA on fifty-one patients. MWA was performed using a NeuWave Certus 140 system, with a typical setting of 65 W and 5 minutes. Ultrasound B-mode and radiofrequency (RF) data loops for EDE were acquired using a Siemens Acuson S2000 system and a 6C1 HD transducer. RF data loops were acquired simultaneously with a manual perturbation of the ablation antenna performed by a physician. EDE strain images were generated with a 2D cross-correlation based displacement tracking algorithm with a kernel size of 1.35 mm × 3.29 mm along the axial and lateral direction. Ablation area, contrast and contrast to noise ratio (CNR) of EDE strain and ultrasound B-mode images were compared. Delineable ablation regions were obtained using EDE for 45 patients, with a success rate of 88.2%. The area of the ablation region in EDE images was 13.3 ± 5.0 cm2, when compared to 7.7 ± 3.2 cm2 with B-mode images. Contrast and CNR obtained with EDE was on the order of 236% and 102%, respectively, significantly higher than values measured in B-mode images (p

Ultrasound elastography is an effective modality for the delineation of thermally ablated regions after liver tumor treatments. Image contrast in elasticity imaging is based on differences in the Young's modulus of local tissue. In this work, we compare our previously introduced electrode displacement elastography (EDE) with a commercially available acoustic radiation force impulse imaging (ARFI) technique, for delineating the post ablation regions. Forty-seven patients diagnosed with either hepatocellular carcinoma (HCC) or metastases underwent microwave ablation (MWA) procedures with a typical setting of 65 W for 5 minutes. EDE and ARFI images were acquired with a Siemens Acuson S2000 system and 6C1 HD transducer. EDE images were generated from a continuous loop of ultrasound radiofrequency (RF) data using a 2D cross-correlation algorithm. ARFI images were obtained using the ‘Virtual Touch’ function available on the Siemens Acuson S2000 system. Delineation of the ablated region was performed by two observers. Imaging depth dependence of EDE and ARFI was evaluated using tissue mimicking (TM) phantoms with the inclusion positioned at different depths. Delineation results from the two observers indicate that the ablated region in ARFI images was recognizable on an average of 19 patients, while delineable ablation boundaries could be generated on an average of 4 patients. With EDE strain images, delineable ablation boundaries were generated on an average of 39 patients, without obvious imaging depth dependence. The TM phantom studies show that differences in inclusion dimensions measured with EDE and ARFI images were within 8%, while image contrast and contrast to noise ratio (CNR) with EDE was 2–3 times higher than that obtained with ARFI. This study showed that monitoring MWA in terms of the delineation rate and CNR was higher with EDE when compared to the commercially available ARFI approach. EDE could therefore become an alternative imaging modality for monitoring MWA procedures for liver tumor treatments in the ablation suite. EDE is also feasible for deeper tumor locations beyond the evaluated imaging depth for ARFI.

Appendicitis is frequently diagnosed in the emergency department, most commonly using CT. The purpose of this study was to compare the diagnostic accuracy of contrast-enhanced MRI with that of contrast-enhanced CT for the diagnosis of appendicitis in adolescents when interpreted by abdominal radiologists and pediatric radiologists.Our study included a prospectively enrolled cohort of 48 patients (12-20 years old) with nontraumatic abdominal pain who underwent CT and MRI. Fellowship-trained abdominal and pediatric radiologists reviewed all CT and MRI studies in randomized order, blinded to patient outcome. Likelihood for appendicitis was rated on a 5-point scale (1, definitely not appendicitis; 5, definitely appendicitis) for CT, the unenhanced portion of the MRI, and the entire contrast-enhanced MRI study. ROC curves were generated and AUC compared for each scan type for all six readers and then stratified by radiologist type. Image test characteristics, interrater reliability, and reading times were compared.Sensitivity and specificity were 85.9% (95% CI, 76.2-92.7%) and 93.8% (95% CI, 89.7-96.7%) for unenhanced MRI, 93.6% (95% CI, 85.6-97.9%) and 94.3% (95% CI, 90.2-97%) for contrast-enhanced MRI, and 93.6% (95% CI, 85.6-97.9%) and 94.3% (95% CI, 90.2-97%) for CT. No difference was found in the diagnostic accuracy or interpretation time when comparing abdominal radiologists to pediatric radiologists (CT, 3.0 min vs 2.8 min; contrast-enhanced MRI, 2.4 min vs 1.8 min; unenhanced MRI, 1.5 min vs 2.3 min). Substantial agreement between abdominal and pediatric radiologists was seen for all methods (κ = 0.72-0.83).The diagnostic accuracy of MRI to diagnose appendicitis was very similar to CT. No statistically significant difference in accuracy was observed between imaging modality or radiologist subspecialty.

Radiologists interpreting body CT scans may be the first to identify osteoporosis and associated vertebral fractures. This study correlates L1 trabecular attenuation measurements with prevalent vertebral body fractures in older adults undergoing routine CT.Mean L1 trabecular attenuation was measured at thoracoabdominal CT in 1966 consecutive adults (983 men and 983 women) 65 years and older (mean age, 74.1 ± 6.6 [SD] years). Sagittal reconstructions and lateral scouts were analyzed for moderate or severe thoracolumbar vertebral compression fractures according to the Genant semiquantitative assessment method. The diagnostic performance of L1 attenuation for the evaluation of prevalent vertebral fractures was assessed, including ROC curve analysis.A total of 162 (8.2%) individuals (mean age, 78.3 years; 66 men, 96 women) had at least one moderate or severe vertebral fracture. The mean L1 attenuation was 70.2 HU among patients with a prevalent fracture, whereas it was 132.3 HU among patients without fracture (p0.001). The prevalence of moderate or severe vertebral compression fractures was 32.5% when L1 attenuation was ≤ 90 HU. Prevalence increased to 49.2% with L1 attenuation of ≤ 50 HU. ROC curve analysis determined an optimal threshold of 90 HU (sensitivity = 86.9%, specificity = 83.9%), with a corresponding AUC of 0.895. The odds ratio of having a moderate or severe vertebral compression fracture was 31.9 for L1 attenuation ≤ 90 HU (95% CI, 20.2-50.5; p0.001).Patients with moderate or severe vertebral compression fractures have significantly lower L1 attenuation values than patients who do not. L1 attenuation ≤ 90 HU may represent an optimal threshold for determining risk for osteoporotic vertebral fractures.

To determine if renal mass biopsy should be performed before or during the ablation procedure with emphasis on complications and rate of ablation for renal cell carcinomas (RCC), benign tumors, and small renal masses without a histologic diagnosis. This HIPAA-compliant, single-center retrospective study was performed under a waiver of informed consent from the institutional review board. Two hundred eighty-four consecutive patients with a small renal mass (≤4.0 cm) treated with percutaneous thermal ablation between January 2001 and January 2015 were included. Two cohorts were identified based upon the timing of renal mass biopsy: separate session two weeks prior to ablation and same session obtained immediately preceding ablation. Clinical and pathologic data were collected including risk factors for non-diagnostic biopsy. Two-sided t test, χ 2 test or Fischer’s exact tests were used to evaluate differences between cohorts. Univariate and multivariate logistic regression models were constructed. A histologic diagnostic was achieved more frequently in the separate session cohort [210/213 (98.6%) vs. 60/71 (84.3%), p

Purpose To evaluate the effects of tumor complexity and technique on early and midterm oncologic efficacy and rate of complications for 100 consecutive biopsy-proved stage T1a renal cell carcinomas (RCCs) treated with percutaneous microwave ablation. Materials and Methods This HIPAA-compliant, single-center retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety-six consecutive patients (68 men, 28 women; mean age, 66 years ± 9.4) with 100 stage T1a N0M0 biopsy-proved RCCs (median diameter, 2.6 cm ± 0.8) underwent percutaneous microwave ablation between March 2011 and June 2015. Patient and procedural data were collected, including body mass index, comorbidities, tumor histologic characteristics and grade, RENAL nephrometry score, number of antennas, generator power, and duration of ablation. Technical success, local tumor progression, and presence of complications were assessed at immediate and follow-up imaging. The Kaplan-Meier method was used for survival analyses. Results Technical success was achieved for all 100 tumors (100%), including 47 moderately and five highly complex RCCs. Median clinical and imaging follow-up was 17 months (range, 0-48 months) and 15 months (range, 0-44 months), respectively. No change in estimated glomerular filtration rate was noted after the procedure (P = .49). There were three (3%) procedure-related complications and six (6%) delayed complications, all urinomas. One case of local tumor progression (1%) was identified 25 months after the procedure. Three-year local progression-free survival, cancer-specific survival, and overall survival were 88% (95% confidence interval: 0.52%, 0.97%), 100% (95% confidence interval: 1.0%, 1.0%), and 91% (95% confidence interval: 0.51%, 0.99%), respectively. Conclusion Percutaneous microwave ablation is an effective and safe treatment option for stage T1a RCC, regardless of tumor complexity. Long-term follow-up is needed to establish durable oncologic efficacy and survival relative to competing ablation modalities and surgery. © RSNA, 2017.

Purpose: Percutaneous radiofrequency ablation and cryoablation are accepted alternative treatments for small renal cell carcinomas (RCC) in high-risk patients. The recent development of high-powered microwave (MW) ablation offers theoretical advantages over existing ablation systems, including higher tissue temperatures, more reproducible ablation zones, and shorter procedural times. The purpose of this study is to review the feasibility, safety, and early efficacy of a novel high-powered percutaneous MW ablation system to treat RCC. Methods: An institutional database identified 53 consecutive patients with biopsy-proven RCC ≤4 cm (55 tumors) who were treated with percutaneous MW ablation using a novel MW ablation system. All patients had percutaneous renal mass biopsy, which identified RCC before ablation. Postprocedure follow-up imaging was performed by contrast-enhanced computed tomography or magnetic resonance imaging. Results: Mean patient age was 66 years and 81% of patients were male. RCC subtypes included clear cell (n=25), papillary (n=12), and unspecified (n=18) and Fuhrman grades 1, 2, 3, and ungraded in 15, 25, 1, and 14 patients, respectively. The mean tumor diameter was 2.6 cm (range 0.8–4.0 cm). Six low-grade complications were recorded during 53 (11.3%) procedures: five Clavien Grade 1 (urine retention, fluid overload, and atrial fibrillation) and one Grade 2 (hemorrhage requiring transfusion). The postprocedure estimated glomerular filtration rate was not significantly changed from preprocedure levels (median: −1.1%, p=0.10). Median follow-up was 8 months (interquartile range [IQR] 5–18.25) with 0/38 (0%) patients demonstrating evidence of local recurrence or metastasis during surveillance imaging. Conclusions: Use of a high-powered MW ablation system for the treatment of T1a RCC is feasible, safe, and efficacious with short-term follow-up. A longer follow-up is warranted to evaluate oncologic outcomes.

Small pulmonary nodules are often difficult to identify during thoracoscopic resection, and preoperative CT-guided localization performed using either hookwire placement or methylene blue injection can be helpful. The purpose of this study is to compare the localization success and complication rates of these two techniques.One hundred two consecutive patients who underwent a total of 109 localization procedures performed with CT fluoroscopic guidance were analyzed. The procedures included 52 hookwire insertions and 57 methylene blue injections. The localization success and complication rates associated with the two groups were compared.All nodules in both groups were identified intraoperatively, except for those in two patients in the hookwire group who did not proceed to undergo same-day surgery, including one with a massive systemic air embolus that resulted in death. Hookwires were dislodged in seven of 52 cases (13%), but the surgeons were still able to locate the nodules through visualization of the parenchymal puncture sites. The total number of complications was higher in the hookwire insertion group than in the methylene blue injection group, but this trend was not statistically significant, with all types of complications occurring in 28 cases (54%) versus 26 cases (46%) (p = 0.45), major complications noted in four cases (8%) versus one case (2%) (p = 0.19), pneumothorax observed in 20 cases (38%) versus 14 cases (25%) (p = 0.15), and perilesional hemorrhage occurring in six cases (12%) versus two cases (4%) (p = 0.15), respectively.The present study suggests that methylene blue injection and hookwire insertion are statistically equivalent for preoperative pulmonary nodule localization; however, seven of 52 hookwires dislodged, and trends toward more frequent and severe complications were noted in the hookwire insertion group.

Microwave ablation has been utilized clinically as an alternative to surgical resection. However, lack of real-time imaging to assess treated regions may compromise treatment outcomes. We previously introduced electrode displacement elastography (EDE) for strain imaging and verified its feasibility in-vivo on porcine animal models. In this study, we evaluated EDE on 44 patients diagnosed with hepatocellular carcinoma, treated using microwave ablation. The ablated region was identified on EDE images for 40 of the 44 patients. Ablation areas with EDE were 13.38 ± 4.99 cm2, when compared to 7.61 ± 3.21 cm2 on B-mode imaging. Contrast and contrast to noise ratios obtained with EDE was on the order of 232% and 98%, respectively, significantly higher than values measured from B mode images (p

To investigate hepatosplenic volumetry at MDCT for non-invasive prediction of hepatic fibrosis. Hepatosplenic volume analysis in 624 patients (mean age, 48.8 years; 311 M/313 F) at MDCT was performed using dedicated software and compared against pathological fibrosis stage (F0 = 374; F1 = 48; F2 = 40; F3 = 65; F4 = 97). The liver segmental volume ratio (LSVR) was defined by Couinaud segments I–III over segments IV–VIII. All pre-cirrhotic fibrosis stages (METAVIR F1-F3) were based on liver biopsy within 1 year of MDCT. LSVR and total splenic volumes increased with stage of fibrosis, with mean(±SD) values of: F0: 0.26 ± 0.06 and 215.1 ± 88.5 mm3; F1: 0.25 ± 0.08 and 294.8 ± 153.4 mm3; F2: 0.331 ± 0.12 and 291.6 ± 197.1 mm3; F3: 0.39 ± 0.15 and 509.6 ± 402.6 mm3; F4: 0.56 ± 0.30 and 790.7 ± 450.3 mm3, respectively. Total hepatic volumes showed poor discrimination (F0: 1674 ± 320 mm3; F4: 1631 ± 691 mm3). For discriminating advanced fibrosis (≥F3), the ROC AUC values for LSVR, total liver volume, splenic volume and LSVR/spleen combined were 0.863, 0.506, 0.890 and 0.947, respectively. Relative changes in segmental liver volumes and total splenic volume allow for non-invasive staging of hepatic fibrosis, whereas total liver volume is a poor predictor. Unlike liver biopsy or elastography, these CT volumetric biomarkers can be obtained retrospectively on routine scans obtained for other indications. • Regional changes in hepatic volume (LSVR) correlate well with degree of fibrosis. • Total liver volume is a very poor predictor of underlying fibrosis. • Total splenic volume is associated with the degree of hepatic fibrosis. • Hepatosplenic volume assessment is comparable to elastography for staging fibrosis. • Unlike elastography, volumetric analysis can be performed retrospectively.

To compare gadoxetic acid alone and combined gadoxetic acid/gadofosveset trisodium-enhanced liver MRI for detection of metastases and differentiation of metastases from haemangiomas. Ninety-one patients underwent gadoxetic acid-enhanced liver MRI before and after additional injection of gadofosveset. First, two readers retrospectively identified metastases on gadoxetic acid alone enhanced delayed hepatobiliary phase T1-weighted images together with all other MR images (dynamic images, T2-weighted images, diffusion-weighted images). Second, readers assessed additional T1-weighted images obtained after administration of gadofosveset trisodium. For both interpretations, readers rated lesion conspicuity and confidence in differentiating metastases from haemangiomas. Results were compared using alternative free-response receiver-operating characteristic (AFROC) and conventional ROC methods. Histology and follow-up served as reference standard. There were 145 metastases and 16 haemangiomas. Both readers detected more metastases using combined gadoxetic acid/gadofosveset (reader 1 = 130; reader 2 = 124) compared to gadoxetic acid alone (reader 1 = 104; reader 2 = 103). Sensitivity of combined gadoxetic acid/gadofosveset (reader 1 = 90 %; reader 2 = 86 %) was higher than that of gadoxetic acid alone (reader 1 = 72 %; reader 2 = 71 %, both P

To compare the sensitivity, specificity, and diagnostic accuracy of fat-only datasets reconstructed using a two-point Dixon technique, with corresponding opposed-phase (OP) and in-phase (IP) datasets for characterization of adrenal lesions at 3 Tesla (T). Fifty-nine patients (21 male, 38 female) with 66 adrenal lesions (49 adenomas, 17 nonadenomas) underwent 3D dual gradient-echo 3-T adrenal MR imaging with reconstruction of OP/IP and fat/water datasets. Sensitivity, specificity, and diagnostic accuracy were compared between OP/IP datasets, using the signal intensity index (SII), and fat/water datasets, using the fat fraction and fat ratio. Four radiologists qualitatively assessed OP/IP and fat-only datasets for reader confidence in lesion characterization and image quality. There were significant differences between adenomas and nonadenomas with regard to mean SII, fat fraction, and fat ratio (P

INTRODUCTION AND OBJECTIVES: Standard percutaneous renal mass biopsy is prone to sampling error in large heterogeneous renal masses, which increases the risk for non-diagnostic results or failure to detect poor prognostic features. The purpose of this study was to compare the accuracy of percutaneous biopsy for large renal masses using a modified multi-quadrant technique (qBx) to standard biopsy technique. METHODS: Clinical and pathologic data for all patients with cT2 renal masses who received percutaneous biopsy using standard or modified techniques at a single institution over a five year period (2009 e 2014) were reviewed with IRB approval. The qBx technique includes multiple core biopsies from at least four separate, solid enhancing areas within the tumor. Standard technique obtained core samples from < 4 areas within the tumor. An expert genitourinary pathologist (WH) performed a blinded review of each biopsy core. RESULTS: In patients with cT2 renal masses, 110 biopsies were performed in 105 patients (45 standard technique and 65 qBx). Mean clinical tumor size was 10 cm (IQR 8-13). Biopsy was nondiagnostic in 5/45 (11.1%) standard and 0/65 (0%) qBx. Nephrectomy was performed after 66 biopsies (21 standard and 45 qBx). When comparing the concordance of biopsy pathology to nephrectomy specimens, biopsy correctly predicted the type of renal neoplasm in 17/ 18 (94.4%) standard biopsies and 45/45 (100%) qBx. In 57 RCC tumors, grade was assigned for both biopsy and nephrectomy specimens. Tumor grade was concordant in 2/14 (14.3%) of standard biopsies and 27/43 (62.8%) qBx. Sarcomatoid de-differentiation was identified in 16/88 (18.2%) of large RCC tumors studied. Sarcomatoid features were identified from biopsy in 10/16 (62.5%) tumors. The ability to identifying sarcomatoid features was higher using multi-quadrant technique compared to the standard technique, 8/10 (80.0%) vs 2/6 (33.3%). One patient who had a biopsy using the standard technique required hospital admission for hemorrhage. No complications were reported in patients when using the qBx technique. CONCLUSIONS: Multi-quadrant biopsy technique increases diagnostic accuracy in large renal tumors.

Percutaneous biopsy obtained from a single location is prone to sampling error in large heterogeneous renal masses, leading to nondiagnostic results or failure to detect poor prognostic features. We evaluated the accuracy of percutaneous biopsy for large renal masses using a modified multi-quadrant technique vs a standard biopsy technique.Clinical and pathological data for all patients with cT2 or greater renal masses who underwent percutaneous biopsy from 2009 to 2014 were reviewed. The multi-quadrant technique was defined as multiple core biopsies from at least 4 separate solid enhancing areas in the tumor. The incidence of nondiagnostic findings, sarcomatoid features and procedural complications was recorded, and concordance between biopsy specimens and nephrectomy pathology was compared.A total of 122 biopsies were performed for 117 tumors in 116 patients (46 using the standard biopsy technique and 76 using the multi-quadrant technique). Median tumor size was 10 cm (IQR 8-12). Biopsy was nondiagnostic in 5 of 46 (10.9%) standard and 0 of 76 (0%) multi-quadrant biopsies (p=0.007). Renal cell carcinoma was identified in 96 of 115 (82.0%) tumors and nonrenal cell carcinoma tumors were identified in 21 (18.0%). One complication occurred using the standard biopsy technique and no complications were reported using the multi-quadrant technique. Sarcomatoid features were present in 23 of 96 (23.9%) large renal cell carcinomas studied. Sensitivity for identifying sarcomatoid features was higher using the multi-quadrant technique compared to the standard biopsy technique at 13 of 15 (86.7%) vs 2 of 8 (25.0%) (p=0.0062).The multi-quadrant percutaneous biopsy technique increases the ability to identify aggressive pathological features in large renal tumors and decreases nondiagnostic biopsy rates.

Identification of patient and tumor characteristics associated with nondiagnostic biopsies is necessary to improve prebiopsy counseling and patient selection.We reviewed the clinical records and prebiopsy imaging of all patients treated with percutaneous biopsy for a renal mass 7 cm or less. Univariate and multivariate logistic regression models were constructed to examine the association between biopsy outcome and clinical/radiographic features.A total of 565 biopsies of renal tumors 7 cm or less in 525 patients were included in the study. There was no significant difference in age, body mass index, Charlson comorbidity score or gender between the patient cohorts with diagnostic and nondiagnostic biopsy. In 83 of 565 patients (14.7%) overall and in 72 of the 413 (17.4%) with a mass of 4 cm or less the biopsy findings were nondiagnostic. Overall 14.7% of masses were cystic and 85.3% were solid with a median tumor size of 2.75 cm (IQR 2.05-4.25). Independent predictors of nondiagnostic biopsy included cystic features, enhancement less than 20 HU, left tumor, tumor diameter and skin-to-tumor distance. The nondiagnostic rate of repeat biopsies was 20.8%, which did not statistically differ from the nondiagnostic rate at the initial renal mass biopsy attempt. Radiologist or pathologist experience was not associated with the biopsy nondiagnostic rate. In 7 of 565 patients (1.2%) hospital admission was required for adverse events after biopsy.Nondiagnostic renal mass biopsies are more common in cystic, nonenhancing, small masses when patients have a skin-to-tumor distance of 13 cm or greater. Excluding patients with these criteria decreased the nondiagnostic rate from 14.7% to 8.7%.

To evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) ablation zones in a porcine model.MW ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection.Antennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected ablations (p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control ablations (mean surface area = 3.8 cm(2)) but only 4/14 gel-protected ablations (mean surface area = 0.2 cm(2); p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery.When used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.