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Purpose The purpose of this study was to evaluate the effectiveness and adverse outcomes of percutaneous cryoablation (CA) for treatment of renal masses in a large cohort of patients. Materials and Methods This retrospective analysis included 299 CA procedures (297 masses in 277 patients) performed between July 2007 and May 2018 at a single institution. The mean patient age was 66.1 years (range, 30–93 years) with 65.8% being male. A total of 234 (78.8%) masses were biopsy-proven renal cell carcinoma (RCC). The mean maximal tumor diameter was 2.5 cm (range, 0.7–6.6 cm). Efficacy was assessed only for ablations of biopsy-proven RCC, whereas the evaluation of adverse events and renal function included all masses. Complications were graded according to the Society of International Radiology classification. Results Major complications occurred in 3.0% of procedures (n = 9), none of which resulted in death or permanent disability. The mean imaging follow-up period was 27.4 months (range, 1–115) for the 199 RCC patients (204 ablated tumors) with follow-up imaging available. Complete response on initial follow-up imaging at mean 4.2 months (range, 0.3–75.6) was achieved in 195 of 204 tumors (95.6%) after a single session and in 200 of 204 tumors (98.0%) after 1 or 2 sessions. Of the RCC patients achieving complete response initially, local recurrence during the follow-up period occurred in 3 of 200 tumors (1.5%). Metastatic progression occurred in 10 of 193 (5.2%) RCC patients without prior metastatic disease during follow-up. Conclusions CA for renal masses is safe and remains efficacious through intermediate- and long-term follow-up.

To compare the cost effectiveness of prostatic artery embolization (PAE) with that of transurethral resection of the prostate (TURP) for the treatment of medically refractory benign prostatic hyperplasia (BPH).A cost-effectiveness analysis with Markov modeling was performed, comparing the clinical course after PAE with that after TURP for 3 years. Probabilities were obtained from the available literature, and costs were based on Medicare reimbursements and published cost analyses. Outcomes were measured using quality-adjusted life-year (QALY). Statistical analyses included base case calculation, probabilistic sensitivity analysis, and deterministic sensitivity analysis to assess the robustness of the conclusion under different clinical scenarios.Base case calculation showed comparable outcomes (PAE, 2.845 QALY; TURP, 2.854 QALY), with a cost difference of $3,104 (PAE, $2,934; TURP, $6,038). The incremental cost-effectiveness ratio was $360,249/QALY. PAE was dominant in 23.2% and more cost effective in 48.4% of the probabilistic sensitivity analysis simulations. PAE was better if its recurrence risk was20.4% per year and even when the TURP recurrence risk was assumed to be 0%. TURP would be more cost effective when its procedural cost was$3,367 or the PAE procedural cost$4,409. PAE remained cost effective when varying the risks and costs of the minor and major short-term or long-term adverse events of both procedures. TURP would be the better strategy if the utility of BPH recurrence was0.85 QALY.PAE is a cost-effective strategy to treat medically refractory BPH, resulting in comparable health benefits at a lower cost than that of TURP even when accounting for extreme alterations in adverse events, costs, and recurrence rates.

Background Aneurysms are rare anomalies of the portomesenteric venous system. Thrombotic complications of these lesions can lead to mesenteric venous ischemia and bowel infarction, potentially requiring surgical intervention. Herein we describe a case of mesenteric ischemia due to a large thrombosed portomesenteric aneurysm treated with endovascular techniques. Case presentation A 37-year-old previously healthy male who presented with abdominal pain to his local emergency department was found to have a thrombosed 12.0 × 5.1 cm portomesenteric venous aneurysm with evidence of mesenteric ischemia on CT. When conservative management with anticoagulation failed, transhepatic pharmacomechanical thrombolysis was initially performed. This was followed by TIPS placement with additional trans-TIPS thrombectomy to improve sluggish portal outflow and prevent re-thrombosis. The patient’s symptoms and imaging findings of ischemia resolved after endovascular therapy. No surgical intervention was required, and the patient was discharged on enoxaparin before being transitioned to apixaban. The TIPS remained patent at 2-year follow-up, with no change in the size of the aneurysm or re-thrombosis noted. The patient’s synthetic liver function was preserved with no evidence of hepatic encephalopathy during the follow-up period. Conclusions Endovascular therapies may be used to manage thrombotic complications of portomesenteric venous aneurysms, obviating the need for surgical intervention in selected patients.

Purpose To evaluate efficacy and safety of transjugular liver biopsy (TJLB) via the left hepatic vein in patients with left lobe–only liver transplants (LLOTs). Materials and Methods Retrospective review revealed 43 TJLBs performed in 26 patients with LLOTs (mean age 51.3 y; range, 18–73 y) between January 2009 and June 2016 at a single institution. A comparison group of 44 randomly selected TJLBs performed in 37 orthotopic whole liver transplant (OWLT) recipients (mean age 57.6 y; range, 35–74 y) during the same time period was evaluated. Patient demographics, type and age of transplant, technical success, adequacy of samples, number of portal tracts obtained, pathologic diagnosis, and complication rate were reviewed. Results Technical success was achieved in 98% (42/43) of LLOT procedures. TJLB failed in 1 patient with LLOT, in whom no patent hepatic veins were identified. Technical success was achieved in 100% (44/44) in the OWLT group. Mean (SD) number of needle passes was 4.12 (1.25) in the LLOT group vs 3.95 (1.28) in the OWLT group (P = .54). Mean (SD) specimen length was 1.16 (0.75) cm in the LLOT group vs 1.19 (0.58) cm in the OWLT group (P = .78). Mean (SD) number of portal tracts obtained in the LLOT group was 10.7 (5.26) vs 12.3 (4.68) in the OWLT group (P = .17). No major complications were observed in either group. Conclusions TJLB in adult patients with LLOTs appears safe and feasible, with favorable rates of technical success and adequacy of sampling.

Central venous stenosis in hemodialysis patients rarely causes venous hypertension and intracranial hemorrhage. A 54 year-old male with right arm arteriovenous fistula was transferred to our institution in a comatose state following right parietal venous infarction. Fistulography showed right brachiocephalic vein (BCV) occlusion with reflux into the right transverse sinus and obstruction of left internal jugular vein outflow due to the styloid process. Balloon venoplasty of the right BCV occlusion failed to improve the patient's status because of the delayed diagnosis. Headaches and neurologic symptoms in hemodialysis patients can herald intracranial hypertension due to central venous occlusion and needs prompt assessment with fistulography.

Purpose To compare the complication rate of the Denali and Option-ELITE inferior vena cava (IVC) filters. Materials and Methods All patients who had a Denali or Option-ELITE IVC filter placed between March 2014 and March 2016 were retrospectively identified from the electronic medical records. Of the 245 IVC filters placed, the positions of 93 devices (21 Denali and 72 Option-ELITE) were documented on follow-up computed tomography (CT) examinations obtained for reasons unrelated to filter placement. In situations where multiple CT studies were obtained after placement, each study was reviewed, for a total of 200 examinations. Images were assessed for filter complication including caval wall penetration by filter components, associated damage to pericaval tissues, filter tilt, migration, and fracture. Results Penetration of at least one strut was observed in 13% of all filters imaged by CT, (Denali: 14%; Option-ELITE: 13%; p = 1.00). No patients had damage to pericaval tissues or documented symptoms attributed to penetration. Neither the Denali nor the Option-ELITE filters demonstrated significant tilt (> 15 degrees of tilt), migration, or fracture. Compared with Denali; the Option-ELITE filter demonstrated an increasing strut penetration rate with longer indwell times (z = –3.67, p < 0.01). Conclusions No significant difference was observed between the rates of caval penetration of the Denali and Option-ELITE IVC filters assessed by CT. Additionally, no findings of filter fracture or migration were noted, suggesting that the Denali filter is non-inferior to the Option-ELITE filter with respect to penetration, fracture, tilt, and migration. The Option-ELITE filter demonstrated a time-dependent tendency toward greater strut penetration with longer indwell times.

Purpose To assess the effectiveness of disposable radiation-absorbing surgical drapes on operator radiation dose during transjugular liver biopsy (TJLB). Materials and Methods This dual-arm prospective, randomized study was conducted between May 2017 and January 2018 at a single institution. TJLB procedures (N = 62; patient age range, 19–80 y) were assigned at a 1:1 ratio to the use of radiation-absorbing surgical drapes or standard surgical draping. The primary outcome was cumulative radiation equivalent dose incident on the operator, as determined by an electronic personal dosimeter worn at the chest during each procedure. Cumulative kerma–area product (KAP), total fluoroscopy time, and total number of exposures used during each liver biopsy procedure were also determined. Results Mean radiation dose incident on the operator decreased by 56% with the use of radiation-absorbing drapes (37 μSv ± 35; range, 4–183 μSv) compared with standard draping (84 μSv ± 58; range, 11–220 μSv). Radiation incident on the patient was similar between groups, with no significant differences in mean KAP, total fluoroscopy time, and number of exposures acquired during the procedures. Conclusions Use of disposable radiation-absorbing drapes reduces scatter radiation to interventionalists performing TJLB.

Nicholas Fidelman,1 Curt Johanson,1 Maureen P Kohi,1 K Pallav Kolli,1 Ryan M Kohlbrenner,1 Evan D Lehrman,1 Andrew G Taylor,1 R Kate Kelley,2 Francis Y Yao,3 John P Roberts,4 Robert K Kerlan11Department of Radiology and Biomedical Imaging; 2Department of Medicine – Division of Gastrointestinal Oncology; 3Department of Medicine – Division of Hepatology; 4Department of Surgery – Division of Transplant Surgery, University of California San Francisco, San Francisco, CA, USAPurpose: To determine whether chemoembolization using drug-eluting beads (DEB-TACE) is safe and effective for liver transplantation candidates with liver-limited hepatocellular carcinoma (HCC) without vascular invasion and baseline hepatic dysfunction.Materials and methods: Seventeen adult liver transplantation candidates (median age 66 years, range 58–73 years; 13 men) with HCC were treated with DEB-TACE as a part of Stage 1 of a prospective single-institution Phase II trial. All patients had marginal hepatic reserve based on at least one of the following criteria: ascites (n=14), bilirubin between 3 and 6 mg/dL (n=5), AST 5–10 times upper normal limit (n=1), INR between 1.6 and 2.5 (n=4), portal vein thrombosis (n=2), and/or portosystemic shunt (n=2). Primary study objectives were safety and best observed radiographic response.Results: Thirty-seven DEB-TACE procedures were performed. Objective response rate and disease control rate were 63% and 88%, respectively. HCC progression was observed in 12 patients. Median time to progression was 5.6 months (range 0.9–13.6 months). Within 1 month following DEB-TACE, 13 patients (76%) developed grade 3 or 4 AE attributable to the procedure. Four patients (all within Milan Criteria) were transplanted (2.7–6.9 months after DEB-TACE), and 12 patients died (1.8–32 months after DEB-TACE). All deaths were due to liver failure that was either unrelated to HCC (n=5), in the setting of metastatic HCC (n=5), or in the setting of locally advanced HCC (n=2). Mortality rate at 1 month was 0%.Conclusions: DEB-TACE achieves tumor responses but carries a high risk of hepatotoxicity for liver transplant candidates with HCC and marginal hepatic reserve.Keywords: hepatocellular carcinoma, chemoembolization, liver transplantation

Opportunities for interventional radiology (IR) education and exposure remain limited at medical institutions without a local IR presence, thereby excluding a medical student population with potential to pursue careers in IR or become referring providers to IR. The purpose of this study was to evaluate the efficacy of a Webinar-based IR elective as an educational tool for outreach to US medical schools lacking local preclinical IR exposure. Our early results indicate that a Webinar-based IR lecture series can serve as an effective method for educating future physicians about the field of IR and when to consult IR for patient management.

Purpose To determine the clinical outcomes of patients who underwent image-guided drainage of peripancreatic fluid collections after simultaneous pancreas-kidney (SPK) transplantation. Materials and Methods A retrospective review of all patients who underwent peripancreatic fluid collection drainage after SPK, from January 2000 to August 2017, at a single institution was performed. Patient characteristics, surgical technique, medication regimen, microbial analysis, and clinical outcomes were reviewed. Thirty-one patients requiring a total of 41 drainages were included in this study. The median age was 44 years (range 30–58 years), and median time between SPK and drainage was 28 days (range 8 to 3,401 days). Fisher’s exact test, unpaired Student t -tests, and Pearson correlations were used for statistical analysis. Results Fever (51%) and abdominal pain (31%) were the most common presenting symptoms. The average amount of fluid drained at the time of drain placement was 97 mL (SD 240 mL). The average time spent with a drain in place was 33 days (SD 31 days). Microorganisms were isolated in the fluid of 22 of 41 drainages (54%), with mixed gastrointestinal flora being the most common. No further intervention was needed in 34 of 41 drainages (82%). However, drainage failed in 5 of 31 patients (16%), requiring surgical intervention with removal of the pancreas transplant. Conclusions Percutaneous drainage of peripancreatic fluid collections after SPK transplantation is a safe and effective treatment option.

To evaluate radiation dose reduction in patients undergoing transarterial chemoembolization with the use of a new image acquisition and processing platform.Radiation-dose data were obtained from 176 consecutive chemoembolization procedures in 135 patients performed in a single angiography suite. From January 2013 through October 2013, 85 procedures were performed by using our institution's standard fluoroscopic settings. After upgrading the x-ray fluoroscopy system with an image acquisition and processing platform designed to reduce image noise and reduce skin entrance dose, 91 chemoembolization procedures were performed from November 2013 through December 2014. Cumulative dose-area product (CDAP), cumulative air kerma (CAK), and total fluoroscopy time were recorded for each procedure. Image quality was assessed by three interventional radiologists blinded to the x-ray acquisition platform used.Patient radiation dose indicators were significantly lower for chemoembolization procedures performed with the novel imaging platform. Mean CDAP decreased from 3,033.2 dGy·cm(2) (range, 600.3-9,404.1 dGy·cm(2)) to 1,640.1 dGy·cm(2) (range, 278.6-6,779.9 dGy·cm(2); 45.9% reduction; P.00001). Mean CAK decreased from 1,445.4 mGy (range, 303.6-5,233.7 mGy) to 971.7 mGy (range, 144.2-3,512.0 mGy; 32.8% reduction; P.0001). A 20.3% increase in mean total fluoroscopy time was noted after upgrading the imaging platform, but blinded analysis of the image quality revealed no significant degradation.Although a small increase in fluoroscopy time was observed, a significant reduction in patient radiation dose was achieved by using the optimized imaging platform, without image quality degradation.

Background: Ventral hernia repair (VHR) is one of the most common surgical procedures and is commonly associated with post procedural fluid collection formation. Purpose: To determine the clinical outcomes of percutaneous drainage of collections adjacent to mesh ventral hernia repair (VHR). Material and Methods: A retrospective review of all consecutive patients who underwent percutaneous drainage of fluid collections adjacent to mesh VHR was performed. Patient characteristics, mesh type, culture results, and clinical outcomes were reviewed. Clinical success was defined as mesh salvage and resolution of presenting signs and symptoms without surgical intervention. Results: A total of 14 patients were included (6 men, 8 women) with median age of 53 years (range: 22- 80 years). Median interval time between VHR and drain placement was 40 days (range: 15-1144 days). Pain was the most common presenting symptom, noted in 13 patients 93%), followed by erythema which was noted in 10 patients (71%). Percutaneous drain insertion was technically successful in all 14 patients (100%). Clinical success was achieved for five out of 14 patients (36%) whose mesh was salvaged. The other nine patients (64%) required mesh excision because of lack of clinical improvement. There was no statistically significant difference in drainage outcomes when comparing patient age, gender, mesh type, interval from surgery to drainage, or bacterial cultures. Conclusion: While percutaneous drainage of collections adjacent to mesh VHR may be successful in some cases, a majority of patients may ultimately require surgical mesh excision.

Venous thromboembolism (VTE) is an extremely common form of vascular disease and impacts a great number of patients worldwide. Acute deep vein thrombosis (DVT) is a subset of VTE and is traditionally been treated with anticoagulation. There is good quality data which suggests the use of catheter directed interventions for the treatment of acute DVT with the aim of reducing post-thrombotic syndrome (PTS). The present review will discuss the various therapies available for acute DVT, focusing on catheter directed interventions, ranging from traditional anticoagulation to the most novel forms of aspiration thrombectomy.

Purpose To assess radiation dose reduction during uterine fibroid embolization (UFE) using an optimized angiographic processing and acquisition platform. Materials and Methods Radiation dose data for 70 women (mean age, 46 y; range, 34–67 y) who underwent UFE were retrospectively analyzed. Twenty-one patients underwent UFE using the baseline fluoroscopic and angiographic image acquisition platform, and 49 underwent UFE after implementing an optimized imaging platform in otherwise identical angiography suites. Cumulative kerma-area product (CKAP), cumulative air kerma (CAK), total fluoroscopy time, and image exposure number were collected for each procedure. Image quality was assessed by 3 interventional radiologists blinded to the platform used for image acquisition and processing. Results Patients undergoing UFE using the new x-ray fluoroscopy platform had significantly lower CKAP and CAK indicators than patients for whom baseline settings were used. Mean CKAP decreased by 60% from 438.5 Gy · cm 2 (range, 180.3–1,081.1 Gy · cm 2 ) to 175.2 Gy · cm 2 (range, 47.1–757.0 Gy · cm 2 ; P P = .001). No degradation of image quality was identified through qualitative evaluation. Conclusions Significant reduction in patient radiation dose indicators can be achieved with use of an optimized image acquisition and processing platform.

The purpose of this study was to evaluate automated CT volumetry in the assessment of living-donor livers for transplant and to compare this technique with software-aided interactive volumetry and manual volumetry.Hepatic CT scans of 18 consecutively registered prospective liver donors were obtained under a liver transplant protocol. Automated liver volumetry was developed on the basis of 3D active-contour segmentation. To establish reference standard liver volumes, a radiologist manually traced the contour of the liver on each CT slice. We compared the results obtained with automated and interactive volumetry with those obtained with the reference standard for this study, manual volumetry.The average interactive liver volume was 1553 ± 343 cm(3), and the average automated liver volume was 1520 ± 378 cm(3). The average manual volume was 1486 ± 343 cm(3). Both interactive and automated volumetric results had excellent agreement with manual volumetric results (intraclass correlation coefficients, 0.96 and 0.94). The average user time for automated volumetry was 0.57 ± 0.06 min/case, whereas those for interactive and manual volumetry were 27.3 ± 4.6 and 39.4 ± 5.5 min/case, the difference being statistically significant (p0.05).Both interactive and automated volumetry are accurate for measuring liver volume with CT, but automated volumetry is substantially more efficient.

A major challenge in computer-aided detection (CAD) of polyps in CT colonography (CTC) is the detection of "difficult" polyps which radiologists are likely to miss. Our purpose was to develop massive-training artificial neural networks (MTANNs) for improving the performance of a CAD scheme on false-negative cases in a large multicenter clinical trial. We developed 3D MTANNs designed to differentiate between polyps and several types of non- polyps and tested on 14 polyps/masses that were actually "missed" by radiologists in the trial. Our initial CAD scheme detected 71.4% of "missed" polyps with 18.9 false positives (FPs) per case. The MTANNs removed 75% of the FPs without loss of any true positives; thus, the performance of our CAD scheme was improved to 4.8 FPs per case at the sensitivity of 71.4% of the polyps "missed" by radiologists.

Purpose: To quantify the patient radiation dose reduction achieved during transarterial chemoembolization (TACE) procedures performed in a body interventional radiology suite equipped with the Philips Allura Clarity imaging acquisition and processing platform, compared to TACE procedures performed in the same suite equipped with the Philips Allura Xper platform. Methods: Total fluoroscopy time, cumulative dose area product, and cumulative air kerma were recorded for the first 25 TACE procedures performed to treat hepatocellular carcinoma (HCC) in a Philips body interventional radiology suite equipped with Philips Allura Clarity. The same data were collected for the prior 85 TACE procedures performed to treat HCC in the same suite equipped with Philips Allura Xper. Mean values from these cohorts were compared using two-tailed t tests. Results: Following installation of the Philips Allura Clarity platform, a 42.8% reduction in mean cumulative dose area product (3033.2 versus 1733.6 mGycm∧2, p < 0.0001) and a 31.2% reduction in mean cumulative air kerma (1445.4 versus 994.2 mGy, p < 0.001) was achieved compared to similar procedures performed in the same suite equipped with the Philips Allura Xper platform. Mean total fluoroscopy time was not significantly different between the two cohorts (1679.3 versus 1791.3 seconds, p = 0.41). Conclusion: This study demonstrates a significant patient radiation dose reduction during TACE procedures performed to treat HCC after a body interventional radiology suite was converted to the Philips Allura Clarity platform from the Philips Allura Xper platform. Future work will focus on evaluation of patient dose reduction in a larger cohort of patients across a broader range of procedures and in specific populations, including obese patients and pediatric patients, and comparison of image quality between the two platforms. Funding for this study was provided by Philips Healthcare, with 5% salary support provided to authors K. Pallav Kolli and Robert G. Gould for time devoted to the study. Data acquisition and analysis was performed by the authors independent of the funding source.

Computerized liver extraction from hepatic CT images is challenging because the liver often abuts other organs of a similar density. The purpose of this study was to develop a computer-aided measurement of liver volumes in hepatic CT.The authors developed a computerized liver extraction scheme based on geodesic active contour segmentation coupled with level-set contour evolution. First, an anisotropic diffusion filter was applied to portal-venous-phase CT images for noise reduction while preserving the liver structure, followed by a scale-specific gradient magnitude filter to enhance the liver boundaries. Then, a nonlinear grayscale converter enhanced the contrast of the liver parenchyma. By using the liver-parenchyma-enhanced image as a speed function, a fast-marching level-set algorithm generated an initial contour that roughly estimated the liver shape. A geodesic active contour segmentation algorithm coupled with level-set contour evolution refined the initial contour to define the liver boundaries more precisely. The liver volume was then calculated using these refined boundaries. Hepatic CT scans of 15 prospective liver donors were obtained under a liver transplant protocol with a multidetector CT system. The liver volumes extracted by the computerized scheme were compared to those traced manually by a radiologist, used as "gold standard."The mean liver volume obtained with our scheme was 1504 cc, whereas the mean gold standard manual volume was 1457 cc, resulting in a mean absolute difference of 105 cc (7.2%). The computer-estimated liver volumetrics agreed excellently with the gold-standard manual volumetrics (intraclass correlation coefficient was 0.95) with no statistically significant difference (F = 0.77; p(For = f) = 0.32). The average accuracy, sensitivity, specificity, and percent volume error were 98.4%, 91.1%, 99.1%, and 7.2%, respectively. Computerized CT liver volumetry would require substantially less completion time (compared to an average of 39 min per case by manual segmentation).The computerized liver extraction scheme provides an efficient and accurate way of measuring liver volumes in CT.

Automatic liver segmentation on CT images is challenging because the liver often abuts other organs of a similar density. Our purpose was to develop an accurate automated liver segmentation scheme for measuring liver volumes. We developed an automated volumetry scheme for the liver in CT based on a 5 step schema. First, an anisotropic smoothing filter was applied to portal-venous phase CT images to remove noise while preserving the liver structure, followed by an edge enhancer to enhance the liver boundary. By using the boundary-enhanced image as a speed function, a fastmarching algorithm generated an initial surface that roughly estimated the liver shape. A geodesic-active-contour segmentation algorithm coupled with level-set contour-evolution refined the initial surface so as to more precisely fit the liver boundary. The liver volume was calculated based on the refined liver surface. Hepatic CT scans of eighteen prospective liver donors were obtained under a liver transplant protocol with a multi-detector CT system. Automated liver volumes obtained were compared with those manually traced by a radiologist, used as "gold standard." The mean liver volume obtained with our scheme was 1,520 cc, whereas the mean manual volume was 1,486 cc, with the mean absolute difference of 104 cc (7.0%). CT liver volumetrics based on an automated scheme agreed excellently with "goldstandard" manual volumetrics (intra-class correlation coefficient was 0.95) with no statistically significant difference (p(F≤f)=0.32), and required substantially less completion time. Our automated scheme provides an efficient and accurate way of measuring liver volumes.

A major challenge in computer-aided detection (CAD) of polyps in CT colonography (CTC) is the detection of "difficult" polyps which radiologists are likely to miss. Our purpose was to develop a CAD scheme incorporating massive-training artificial neural networks (MTANNs) and to evaluate its performance on false-negative (FN) cases in a large multicenter clinical trial. We developed an initial polyp-detection scheme consisting of colon segmentation based on CT value-based analysis, detection of polyp candidates based on morphologic analysis, and quadratic discriminant analysis based on 3D pattern features for classification. For reduction of false-positive (FP) detections, we developed multiple expert 3D MTANNs designed to differentiate between polyps and seven types of non-polyps. Our independent database was obtained from CTC scans of 155 patients with polyps from a multicenter trial in which 15 medical institutions participated nationwide. Among them, about 45% patients received FN interpretations in CTC. For testing our CAD, 14 cases with 14 polyps/masses were randomly selected from the FN cases. Lesion sizes ranged from 6-35 mm, with an average of 10 mm. The initial CAD scheme detected 71.4% (10/14) of "missed" polyps, including sessile polyps and polyps on folds, with 18.9 (264/14) FPs per case. The MTANNs removed 75% (197/264) of the FPs without loss of any true positives; thus, the performance of our CAD scheme was improved to 4.8 (67/14) FPs per case. With our CAD scheme incorporating MTANNs, 71.4% of polyps "missed" by radiologists in the trial were detected correctly, with a reasonable number of FPs.

Purpose: Hepatocellular carcinoma (HCC) is one of the most common primary malignant tumors of the liver. We developed a computer‐aided diagnostic(CAD) scheme for detection of HCC in arterial‐phase hepatic CT in order to assist radiologists in their HCC detection. Materials and Methods: Our database consists of isotropic arterial‐phase CT scans of 14 patients acquired with a multi‐detector‐row CT system with a 64 channel detector scanner, which includes 16 radiologist‐determined HCCs that were confirmed pathologically. Lesion sizes ranged 6–50 mm, with a mean of 22.6 mm. We developed a CAD scheme consisting of 1) liver segmentation, using fast‐marching rough‐segmentation followed by geodesic‐active‐contour fine‐segmentation coupled with a level‐set algorithm, 2) detection of HCC candidates from the segmented liver, based on a watershed segmentation algorithm, 3) calculation of both 2D and 3D morphologic‐, intensity‐ and texture‐based features of the detected candidates, and 4) classification of HCC candidates by means of linear discriminant analysis (LDA) of the calculated features, with a stepwise feature selection method based on the Wilks. lambda and the F value. The performance of the CAD scheme was evaluated by free‐response receiver‐operating‐characteristic analysis. Results: With the candidate selection segment of the detection scheme, we achieved 100% sensitivity with 15.1 false positives per patient. Of the 254 calculated features, the stepwise LDA selected 45 “useful” features for candidate characterization. Using these 45 features, we decreased the false positive rate to 6.1 false positives per patient, with no loss in sensitivity. Conclusion: In contrast‐enhanced arterial‐phase hepatic CT, our CAD scheme achieved a 100% sensitivity in detection of HCCs with 6.1 false positives per patient. This detection scheme could assist radiologists in detecting HCCs; thus, it would potentially improve radiologists' detection sensitivity for HCCs.