Steven S. Raman

Influence of Large Peritumoral Vessels on Outcome of Radiofrequency Ablation of Liver Tumors

PURPOSE The effect of large vessels (>/=3 mm) contiguous to hepatic tumors was evaluated with respect to clinical tumor recurrence rates after radiofrequency (RF) ablation. MATERIALS AND METHODS The first 105 malignant liver tumors treated by RF ablation therapy at our institution with pathologic analysis or a minimum of 6 months of clinical follow-up were reviewed. The original pretreatment imaging studies were reviewed by a radiologist who was blinded to the cases, and, based on lesion contiguity to vessels of at least 3 mm, the lesions were categorized as perivascular or nonperivascular. Treatment outcomes with respect to local tumor recurrence between these two groups were then compared. Logistic regression analysis was performed to take into account other variables and to determine whether this categorization was an independent predictor of treatment outcome. RESULTS There were 74 nonperivascular tumors and 31 perivascular tumors. Mean tumor size was 2.4 cm and mean follow-up was 11.3 months. Residual or locally recurrent tumors were documented in 20 of 105 cases (19%). In the nonperivascular group, five of 74 (7%) had either incompletely treated tumor (manifested within 6 months) or local recurrence beyond 6 months. In the perivascular group, 15 of 31 (48%) had incompletely treated or locally recurrent tumor (P <.001). Subanalysis of lesion size (61 tumors </=2.5 cm, 33 tumors 2.6-4 cm, and 11 tumors >4 cm), tumor type (40 hepatocellular carcinomas, 48 colorectal metastases, and 17 other metastases), access (53 intraoperative, 52 percutaneous), and RF device (45 Radiotherapeutics electrodes, 18 Rita electrodes, and 42 Radionics electrodes) showed similar results. Multivariate logistic regression analysis showed that presence or absence of a large peritumoral vessel is an independent, and the dominant, predictor of treatment outcome. CONCLUSION The presence of vessels at least 3 mm in size contiguous to hepatic tumors is a strong independent predictor of incomplete tumor destruction by RF ablation. Modified ablation strategies should be considered to improve destruction of these tumors.

Percutaneous radiofrequency ablation of hepatocellular carcinoma as a bridge to liver transplantation

Orthotopic liver transplantation (OLT) can be a definitive treatment for patients with hepatocellular carcinoma (HCC). Prolonged waiting times for cadaveric livers, however, may lead to dropout from the waiting list or worsened post‐OLT prognosis as a result of interval tumor progression. Percutaneous radiofrequency ablation (RFA) is widely used for local control of small unresectable HCC, but its pretransplant role remains unclear. We studied the outcome of 52 consecutive patients accepted for OLT bearing 87 HCC nodules and treated with percutaneous RFA. On initial staging, the tumor burden exceeded the Milan criteria in 10 patients. Complete tumor coagulation was observed in 74 of 87 (85.1%) nodules based on postablation imaging. After a mean of 12.7 months (range: 0.3‐43.5) on the waiting list, 3 of 52 patients (5.8%) had dropped out due to tumor progression. Forty‐one patients had undergone transplantation, with 1‐ and 3‐year post‐OLT survival rates of 85% and 76%, respectively. No patient developed HCC recurrence. There were three major complications in 76 RFA procedures (hepatic arterial hemorrhage, small bowel perforation, and liver decompensation salvaged by OLT), without resultant death or dropout. In conclusion, percutaneous RFA is an effective bridge to OLT for patients with compensated liver function and safely accessible tumors. Tumor‐related dropout rate and post‐OLT outcome compared favorably with published controls of patients with early‐stage disease. This can be attributed to the efficacy of RFA in producing local cure or curbing tumor progression during the waiting period. (HEPATOLOGY 2005;41:1130–1137.)

Microwave Liver Ablation : Influence of Hepatic Vein Size on Heat-sink Effect in a Porcine Model

PURPOSE To determine influence of hepatic vein size on perfusion-mediated attenuation in adjacent microwave thermal ablation. MATERIALS AND METHODS With approval of the institutional animal research committee, seven Yorkshire pigs underwent percutaneous (n = 2) or open (n = 5) microwave liver ablation under general anesthesia. In each, multiple ultrasound-guided, nonoverlapping thermal lesions were created within 1 cm of hepatic veins in a 5-10-minute ablation at 45 W. After euthanasia, the liver was harvested and sectioned at 0.5-cm intervals and the degree of perivascular coagulation attenuation was graded on histopathologic analysis. Correlation between venous size (small, < or =3 mm; medium, 3-6 mm; and large, >6 mm) and attenuation grade was performed with use of the Spearman rank test. RESULTS In 63 of 103 sections (61%)--29 of 37 (78%) small, 27 of 48 (56%) medium, and seven of 18 (39%) large veins--the thermal injury extended to the vein wall around the entire circumference of the coagulation front without distortion of the ablation margin. In 40 of 103 sections (38.9%), varying degrees of concave distortion of perivenous ablation margins were noted, with significant correlation between vein size and heat-sink extent (P < .01). However, thermal injury extended to the vascular wall in all sections without complete circumferential sparing of liver tissue. Around two thrombosed veins, thermal lesions encased the vessels, producing paradoxically convex ablation margins. CONCLUSIONS Although the heat-sink effect was significantly dependent on hepatic vein size, the majority of pathologic sections exhibited no or minimal effect. Further study is required to assess clinical implications.

Multifocality and Prostate Cancer Detection by Multiparametric Magnetic Resonance Imaging: Correlation with Whole-mount Histopathology

BACKGROUND Multiparametric magnetic resonance imaging (mp-MRI) is increasingly used in prostate cancer (CaP). Understanding the limitations of tumor detection, particularly in multifocal disease, is important in its clinical application. OBJECTIVE To determine predictors of CaP detection by mp-MRI as confirmed by whole-mount histopathology. DESIGN, SETTING, AND PARTICIPANTS A retrospective study was performed of 122 consecutive men who underwent mp-MRI before radical prostatectomy at a single referral academic center. A genitourinary radiologist and pathologist collectively determined concordance. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS The odds of tumor detection were calculated for clinical, MRI, and histopathologic variables using a multivariate logistic regression model. RESULTS AND LIMITATIONS The 122 patients had 283 unique histologically confirmed CaP tumor foci. Gleason score was 6 in 21 (17%), 7 in 88 (72%), and ≥8 in 13 (11%) patients. Of the 122 cases, 44 (36%) had solitary and 78 (64%) had multifocal tumors. Overall mp-MRI sensitivity for tumor detection was 47% (132/283), with increased sensitivity for larger (102/141 [72%] >1.0 cm), higher-grade (96/134 [72%] Gleason ≥7) tumors, and index tumors (98/122 [80%]). Index tumor status, size, and prostate weight were significant predictors of detection in a multivariate analysis, and multifocality did not adversely impact detection of index tumors. A prostatectomy population was necessary by design, which may limit the ability to generalize these results. CONCLUSIONS Sensitivity for tumor detection increased with tumor size and grade. Index tumor status and tumor size were the strongest predictors of tumor detection, regardless of tumor focality. Some 80% of index tumors were detected, but nonindex tumor detection, even of high-grade lesions, was poor. These findings have important implications for focal therapy. PATIENT SUMMARY We evaluated the ability of magnetic resonance imaging (MRI) to detect cancer in patients undergoing prostatectomy. We found that tumor size and grade were important predictors of tumor detection, and although cancer is often multifocal, MRI is often able to detect the worst focus of cancer.

Evaluation of the Guidelines for Management of Pancreatic Branch-Duct Intraductal Papillary Mucinous Neoplasm

BACKGROUND & AIMS The 2006 Sendai Consensus Guidelines recommend surgical resection for all suspected branch-duct intraductal papillary mucinous neoplasm (BD-IPMN) greater than 3 cm irrespective of symptoms, and those less than 3 cm with worrisome features. We aimed to evaluate the surgical characteristics of these guidelines retrospectively in pathologically confirmed cases of BD-IPMN. METHODS IPMNs resected at our institution (1995-2006) were classified as main-duct predominant or branch-duct (BD) predominant based on preoperative imaging and postoperative histology. Resected BD-IPMNs were classified histologically: low risk (adenoma, borderline) and high risk (carcinoma in situ or invasive cancer). Clinical data (presence of symptoms, mural nodule, dilated pancreatic duct, and cyst size) were correlated with pathology. RESULTS Between 1995 and 2006, there were 204 patients who underwent surgical resection of pancreatic cysts. Sixty-one patients had IPMN including 31 with BD-IPMN. A total of 74.2% (23 of 31) of BD-IPMNs would have been recommended for surgical resection including 69.2% (18 of 26) of low-risk lesions and 100% (5 of 5) of high-risk lesions. All 8 cases of BD-IPMN that would have been recommended for nonsurgical management were low-risk lesions. The positive predictive value of the guidelines is 21.7% (95% confidence interval, 9.7%-41.9%). The negative predictive value is 100% (95% confidence interval, 67.6%-100.0%). Between 2000 and 2007, 351 patients with likely BD-IPMN were evaluated but not resected. CONCLUSIONS Implementation of the Consensus Guidelines to our single-institution, referral-based, surgical BD-IPMN population would have recommended resection of all histologically high-risk lesions. All lesions recommended for nonsurgical management were histologically low-risk lesions. For presumed BD-IPMNs less than 3 cm, the application of the Consensus Guidelines may reduce the resection rate for low-risk lesions.

Clear cell renal cell carcinoma: discrimination from other renal cell carcinoma subtypes and oncocytoma at multiphasic multidetector CT.

PURPOSE To determine whether enhancement at multiphasic multidetector computed tomography (CT) can help differentiate clear cell renal cell carcinoma (RCC) from oncocytoma, papillary RCC, and chromophobe RCC. MATERIALS AND METHODS With institutional review board approval for this HIPAA-compliant retrospective study, the pathology database was queried to derive a cohort of 298 cases of RCC and oncocytoma with preoperative multiphasic multidetector CT with as many as four phases (unenhanced, corticomedullary, nephrographic, and excretory). A total of 170 clear cell RCCs, 57 papillary RCCs, 49 oncocytomas, and 22 chromophobe RCCs were evaluated for multiphasic enhancement and compared by using t tests. Cutoff analysis was performed to determine optimal threshold levels to discriminate among the four groups. RESULTS Mean enhancement of clear cell RCCs and oncocytomas peaked in the corticomedullary phase; mean enhancement of papillary and chromophobe RCCs peaked in the nephrographic phase. Enhancement of clear cell RCCs was greater than that of oncocytomas in the corticomedullary (125 HU vs 106 HU, P = .045) and excretory (80 HU vs 67 HU, P = .034) phases. Enhancement of clear cell RCCs was greater than that of papillary RCCs in the corticomedullary (125 HU vs 54 HU, P < .001), nephrographic (103 HU vs 64 HU, P < .001), and excretory (80 HU vs 54 HU, P < .001) phases. Enhancement of clear cell RCCs was greater than that of chromophobe RCCs in the corticomedullary (125 HU vs 74 HU, P < .001) and excretory (80 HU vs 60 HU, P = .008) phases. Thresholding of enhancement helped to discriminate clear cell RCC from oncocytoma, papillary RCC, and chromophobe RCC with accuracies of 77% (83 of 108 cases), 85% (101 of 119 cases), and 84% (81 of 97 cases). CONCLUSION Enhancement at multiphasic multidetector CT, if prospectively validated, may assist in the discrimination of clear cell RCC from oncocytoma, papillary RCC, and chromophobe RCC.

CT and MRI Improve Detection of Hepatocellular Carcinoma, Compared With Ultrasound Alone, in Patients With Cirrhosis

BACKGROUND & AIMS In patients with cirrhosis, hepatocellular carcinoma (HCC) is detected by ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI); US is recommended for screening and surveillance. We performed a retrospective analysis of the abilities of these cross-sectional imaging modalities to detect HCC. METHODS We analyzed data from 638 consecutive adult patients with cirrhosis who received liver transplants within 6 months of imaging at a tertiary care institution. Imaging reports and serum alpha-fetoprotein levels were compared with results from pathology analysis of explants as the reference standard. Sensitivities of US, CT, and MRI were calculated overall and in defined size categories. False-positive imaging results and patient-based specificities were evaluated. RESULTS Of the 638 patients, 225 (35%) had HCC, confirmed by pathology analysis of liver explants. In 23 cases, the lesions were infiltrative or extensively multifocal. In the remaining 202 explants (337 numerable, discrete nodules), respective lesion-based sensitivities of US, CT, and MRI were 46%, 65%, and 72% overall and 21%, 40%, and 47% for small (<2 cm) HCC. The sensitivity of US increased with the availability of CT or MRI data (P = .049); sensitivity values were 62% and 85% for lesions 2-4 and ≥ 4 cm, respectively. Patient-based specificities of US, CT, and MRI were 96%, 96%, and 87%, respectively. CONCLUSIONS US, CT, and MRI did not detect small HCC lesions with high levels of sensitivity, although CT and MRI provide substantial improvements over unenhanced US in patients with cirrhosis who received liver transplants.

Use of MR imaging to determine preservation of the neurovascular bundles at robotic-assisted laparoscopic prostatectomy.

PURPOSE To determine whether findings at preoperative endorectal coil magnetic resonance (MR) imaging influence the decision to preserve neurovascular bundles and the extent of surgical margins in robotic-assisted laparoscopic prostatectomy (RALP). MATERIALS AND METHODS This study was approved by the investigational review board and was compliant with the HIPAA; the requirement to obtain informed consent was waived. The authors prospectively evaluated 104 consecutive men with biopsy-proved prostate cancer who underwent preoperative endorectal coil MR imaging of the prostate and subsequent RALP. MR imaging was performed at 1.5 T between January 2004 and April 2008 and included T2-weighted imaging (n = 104), diffusion-weighted imaging (n = 88), dynamic contrast-enhanced imaging (n = 51), and MR spectroscopy (n = 91). One surgeon determined the planned preoperative extent of resection bilaterally on the basis of clinical information and then again after review of the final MR imaging report. The differences in the surgical plan before and after review of the MR imaging report were determined and compared with the actual surgical and pathologic results by using logistic regression analysis. Continuous and ranked variables underwent Pearson and Spearman analysis. RESULTS After review of MR imaging results, the initial surgical plan was changed in 28 of the 104 patients (27%); the surgical plan was changed to a nerve-sparing technique in 17 of the 28 patients (61%) and to a non-nerve-sparing technique in 11 (39%). Seven of the 104 patients (6.7%) had positive surgical margins. In patients whose surgical plan was changed to a nerve-sparing technique, there were no positive margins on the side of the prostate with a change in treatment plan. CONCLUSION Preoperative prostate MR imaging data changed the decision to use a nerve-sparing technique during RALP in 27% of patients in this series.

Percutaneous Ablation of Hepatocellular Carcinoma: Current Status

Hepatocellular carcinoma (HCC) is an increasingly common disease with dismal long-term survival. Percutaneous ablation has gained popularity as a minimally invasive, potentially curative therapy for HCC in nonoperative candidates. The seminal technique of percutaneous ethanol injection has been largely supplanted by newer modalities, including radiofrequency ablation, microwave ablation, cryoablation, and high-intensity focused ultrasound ablation. A review of these modalities, including technical success, survival rates, and complications, will be presented, as well as considerations for treatment planning and follow-up.

Utility of 16-MDCT Angiography for Comprehensive Preoperative Vascular Evaluation of Laparoscopic Renal Donors

OBJECTIVE Our objective was to determine the efficacy of 16-MDCT angiography in preoperative evaluation of vascular anatomy of laparoscopic renal donors. METHODS AND MATERIALS Fifty-five consecutive renal donors (25 men and 30 women) underwent 16-MDCT angiography followed by donor nephrectomy. In the arterial and nephrographic phases, images were acquired with 60% overlap and 0.6-mm reconstruction in both phases after 120 mL of iohexol was injected at 4 mL/sec. On a 3D workstation, images were evaluated retrospectively by two abdominal imagers blinded to surgical results with respect to number and branching pattern of renal arteries and major and minor renal veins. These CT angiography results were compared with surgical findings. RESULTS The surgically confirmed sensitivity of both reviewers (1 and 2) using the MDCT data for detection of renal arteries was 98.5% (65 of 66), and accuracies were 97.0% for reviewer 1 and 95.5% for reviewer 2. Sensitivity and accuracy detection of renal veins was 97% (61 of 63) and 98% (62 of 63) for reviewer 1 and reviewer 2, respectively. Sensitivity and accuracy detection of early arterial bifurcation (< 2 cm from aorta) was 100% (14 of 14), and sensitivity in detection of late venous confluence (< 1.5 cm from aorta) was 100% (8 of 8). All major renal venous variants were identified; reviewer 1 identified 78% (18 of 23) minor venous variants, and reviewer 2 identified 83% (19 of 23) minor venous variants. There were no hemorrhagic complications at surgery. Excellent agreement between reviewers (kappa = 0.92-0.97) was achieved for detection of normal and variant anatomy. CONCLUSION 16-MDCT angiography enabled excellent preoperative detection of arterial anatomy and venous laparoscopic donor nephrectomy.