The prevalence of Barrett's esophagus in the US: estimates from a simulation model confirmed by SEER data.

Barrett's esophagus (BE) is the precursor and the biggest risk factor for esophageal adenocarcinoma (EAC), the solid cancer with the fastest rising incidence in the US and western world. Current strategies to decrease morbidity and mortality from EAC have focused on identifying and surveying patients with BE using upper endoscopy. An accurate estimate of the number of patients with BE in the population is important to inform public health policy and to prioritize resources for potential screening and management programs. However, the true prevalence of BE is difficult to ascertain because the condition frequently is symptomatically silent, and the numerous clinical studies that have analyzed BE prevalence have produced a wide range of estimates. The aim of this study was to use a computer simulation disease model of EAC to determine the estimates for BE prevalence that best align with US Surveillance Epidemiology and End Results (SEER) cancer registry data. A previously developed mathematical model of EAC was modified to perform this analysis. The model consists of six health states: normal, gastroesophageal reflux disease (GERD), BE, undetected cancer, detected cancer, and death. Published literature regarding the transition rates between these states were used to provide boundaries. During the one million computer simulations that were performed, these transition rates were systematically varied, producing differing prevalences for the numerous health states. Two filters were sequentially applied to select out superior simulations that were most consistent with clinical data. First, among these million simulations, the 1000 that best reproduced SEER cancer incidence data were selected. Next, of those 1000 best simulations, the 100 with an overall calculated BE to Detected Cancer rates closest to published estimates were selected. Finally, the prevalence of BE in the final set of best 100 simulations was analyzed. We present histogram data depicting BE prevalences for all one million simulations, the 1000 simulations that best approximate SEER data, and the final set of 100 simulations. Using the best 100 simulations, we estimate the prevalence of BE to be 5.6% (5.49-5.70%). Using our model, an estimated prevalence for BE in the general population of 5.6% (5.49-5.70%) accurately predicts incidence rates for EAC reported to the US SEER cancer registry. Future clinical studies are needed to confirm our estimate.

Comparing and predicting the costs and outcomes of patients with major and minor stroke using the Boston Acute Stroke Imaging Scale neuroimaging classification system.

BACKGROUND AND PURPOSE: A neuroimaging-based ischemic stroke classification system that predicts costs and outcomes would be useful for clinical prognostication and hospital resource planning. The Boston Acute Stroke Imaging Scale (BASIS), a neuroimaging-based ischemic stroke classification system, was tested to determine whether it was able to predict the costs and clinical outcomes of patients with stroke at an urban academic medical center. MATERIALS AND METHODS: Patients with ischemic stroke who presented in the emergency department in 2000 (230 patients) and 2005 (250 patients) were classified by using BASIS as having either a major or minor stroke. Compared outcomes included death, length of hospitalization, discharge disposition, use of imaging and intensive care unit (ICU) resources, and total in-hospital cost. Continuous variables were compared by univariate analysis by using the Student t test or the Satterthwaite test adjusted for unequal variances. Categoric variables were tested with the chi(2) test. Multiple regression analyses related total hospital cost (dependent variable) to stroke severity (major versus minor), sex, age, presence of comorbidities, and death during hospitalization. Logistic regression analysis was applied to identify the significant predictive variables indicating a greater likelihood of discharge home. RESULTS: In both years, individuals with strokes classified as major had a significantly longer length of stay, spent more days in the ICU, and had a higher cost of hospitalization than patients with minor strokes (all outcomes, P < .0001). All deaths (8 in 2000, 26 in 2005) occurred in patients with major stroke. Whereas 73% of patients with minor stroke were discharged home, only 12.2% of patients with major stroke were discharged home (P < .0001); 61% of patients with major stroke were discharged to a rehabilitation or skilled nursing facility. Patients with major stroke cost 4.4 times and 3.0 times that of patients with minor stroke in 2000 and 2005, respectively. Making up less than one third of all patients, patients with major stroke accounted for 60% of the total in-hospital cost of acute stroke care. CONCLUSIONS: BASIS, a neuroimaging-based stroke classification system, is highly effective at predicting in-hospital resource use, acute-hospitalization cost, and outcome. Predictive ability was maintained across the years studied.

Comparison of excretory phase, helical computed tomography with intravenous urography in patients with painless haematuria.

AIM: To compare excretory phase, helical computed tomography (CT) with intravenous (IV) urography for evaluation of the urinary tract in patients with painless haematuria. MATERIALS AND METHODS: Ninety-one out-patients had IV urography followed by helical CT limited to the urinary tract. Both IV urograms and CT images were evaluated for abnormalities of the urinary tract in a blinded, prospective manner. The clinical significance of abnormalities was scored subjectively and receiver operator characteristic curve analysis was performed. RESULTS: In 69 of 91 patients (76%), no cause of haematuria was identified. In 22 of 91 patients (24%), the cause of haematuria was identified as follows: transitional cell cancer of the bladder (n=15), urinary tract stones (n=3), cystitis (n=2), haemorrhagic pyelitis (n=1) and benign ureteral stricture (n=1). With IV urography, there were 15 true-positive, seven false-negative and three false-positive interpretations. With CT, there were 18 true-positive, four false-negative and two false-positive interpretations. There was no significant difference between IV and CT urography for the significance of the positive interpretations (n=0.47). CONCLUSION: Excretory phase CT urography was comparable with IV urography for evaluation of the urinary tract in patients with painless haematuria. However, the study population did not include any upper tract cancers.

A cost--utility analysis of treatment options for inguinal hernia in 1,513,008 adult patients.

BACKGROUND: The controversial issue of the cost-effectiveness of laparoscopic inguinal hernia repair is examined, employing a decision analytic method. MATERIALS AND METHODS: The NSAS, NHDS (National Center for Health Statistics), HCUP-NIS (Agency for Healthcare Research and Quality) databases and 51 randomized controlled trials were analyzed. The study group constituted of a total of 1,513,008 hernia repairs. Projection of the clinical, economic, and quality-of-life outcomes expected from the different treatment options was done by using a Markov Monte Carlo decision model. Two logistic regression models were used to predict the probability of hospital admission after an ambulatory procedure and the probability of death after inguinal hernia repair. Four treatment strategies were modeled: (1) laparoscopic repair (LR), (2) open mesh (OM), (3) open non-mesh (ONM), and (4) expectant management. Costs were expressed in US dollars and effectiveness in quality-adjusted life years (QALYs). The main outcome measures were the average and the incremental cost-effectiveness (ICER) ratios. RESULTS: Compared to the expectant management, the incremental cost per QALY gained was 605 dollars (4086 dollars, 9.04 QALYs) for LR, 697 dollars (4290 dollars, 8.975 QALYs) for OM, and 1711 dollars (6200 dollars, 8.546 QALYs) for ONM. In sensitivity analysis the two major components that affect the cost-effectiveness ratio of the different types of repair were the ambulatory facility cost and the recurrence rate. At a LR ambulatory facility cost of 5526 dollars the ICER of LR compared to OM surpasses the threshold of 50,000 dollars/QALY. CONCLUSIONS: On the basis of our assumptions this mathematical model shows that from a societal perspective laparoscopic approach can be a cost-effective treatment option for inguinal hernia repair.

Colorectal cancer screening issues: a role for CT colonography?

Colorectal cancer is the third most common cancer in the United States and will cause 56,700 deaths in 2001, despite the availability of screening tests capable of detecting the disease at earlier stages and reducing mortality. This article reviews the natural history of colorectal cancer, common risk factors and prevention strategies, and the strengths, limitations, and cost effectiveness of available screening tests. Although reminders to undergo colorectal cancer screening have become commonplace in the popular media, compliance with screening guidelines remains poor. Although still an unproven technology for widespread screening, computed tomographic (CT) colonography has several attractive characteristics for a screening test. For example, CT scanners are widely available, in contrast to limited numbers of gastroenterologists and radiologists' declining skill and interest in barium enema examinations. Also, patients may be less reluctant to undergo CT colonography than screening colonoscopy. Development of virtual bowel cleansing could further increase compliance and thereby reduce mortality from colorectal cancer. Other articles in this Feature Section discuss technical details of CT colonography and its methodologic challenges.

Potential influence of acute CT on inpatient costs in patients with ischemic stroke.

RATIONALE AND OBJECTIVES: Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. MATERIALS AND METHODS: By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. RESULTS: The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. CONCLUSION: The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.

Pancreatic cancer: cost-effectiveness of imaging technologies for assessing resectability.

PURPOSE: To evaluate the cost-effectiveness of imaging strategies for the assessment of resectability in patients with pancreatic cancer. MATERIALS AND METHODS: A decision model was developed to calculate costs and benefits (survival) accruing to hypothetical cohorts of patients with known or suspected pancreatic cancer. Results are presented as cost per life-year gained under various scenarios and assumptions of diagnostic test characteristics, surgical mortality, disease characteristics, and costs. RESULTS: With best estimates for all data inputs, the strategy of computed tomography (CT) followed by laparoscopy and laparoscopic ultrasonography (US) had an incremental cost-effectiveness ratio of $87,502 per life-year gained, compared with best supportive care. This strategy was significantly more cost-effective than CT followed by magnetic resonance (MR) imaging and was significantly less expensive than other imaging strategies while providing a statistically and clinically insignificant difference in life-year gains. A strategy involving no imaging (immediate surgery) was more expensive but less effective than all imaging strategies. A hypothetical perfect test with cost equal to that of CT followed by MR had an incremental cost-effectiveness ratio of $64,401 per life-year gained, compared to best supportive care. CONCLUSION: Most available imaging tests for assessing resectability of pancreatic cancer do not differ in effectiveness, but a strategy of CT, laparoscopy, and laparoscopic US would consistently result in significantly lower costs than other imaging tests under a wide range of scenarios.

Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients.

PURPOSE: To describe the results of an ongoing radio-frequency (RF) ablation study in patients with hepatic metastases from colorectal carcinoma. MATERIALS AND METHODS: In 117 patients, 179 metachronous colorectal carcinoma hepatic metastases (0.9-9.6 cm in diameter) were treated with RF ablation by using 17-gauge internally cooled electrodes. Computed tomographic follow-up was performed every 4-6 months. Recurrent tumors were retreated when feasible. Time to new metastases and death for each patient and time to local recurrence for individual lesions were modeled with Kaplan-Meier analysis. Modeling determined the effect of number of metastases on the time to new metastases and death and effect of tumor size on local recurrence. RESULTS: Estimated median survival was 36 months (95% CI; 28, 52 months). Estimated 1, 2, and 3-year survival rates were 93%, 69%, and 46%, respectively. Survival was not significantly related to number of metastases treated. In 77 (66%) of 117 patients, new metastases were observed at follow-up. Estimated median time until new metastases was 12 months (95% CI; 10, 18 months). Percentages of patients with no new metastases after initial treatment at 1 and 2 years were 49% and 35%, respectively. Time to new metastases was not significantly related to number of metastases. Seventy (39%) of 179 lesions developed local recurrence after treatment. Of these, 54 were observed by 6 months and 67 by 1 year. No local recurrence was observed after 18 months. Frequency and time to local recurrence were related to lesion size (P < or =.001). CONCLUSION: RF ablation is an effective method to treat hepatic metastases from colorectal carcinoma.

Endovascular versus open surgical elective repair of infrarenal abdominal aortic aneurysm: predictors of patient discharge destination.

PURPOSE: To evaluate patient discharge destination after elective endovascular or open surgical repair of infrarenal abdominal aortic aneurysm and to determine predictors for discharge to home or to a rehabilitation center. MATERIALS AND METHODS: All patients electively treated for infrarenal abdominal aortic aneurysm with endovascular repair (n = 182) or open surgery (n = 274) between January 1997 and September 1999 were included. From the hospital database, information on discharge destination, patient characteristics, complications, and length of stay was retrieved. Multiple logistic regression analysis was performed to determine predictors for discharge to home or to a rehabilitation center. RESULTS: Patient characteristics did not differ significantly between the treatment groups, with the exception of age (mean age, 75.1 vs 72.9 years in the endovascular and open surgical group, respectively; P =.005). Patient discharge destinations differed significantly between the treatment groups (P =.001). After endovascular procedures, 156 (85.7%) of 182 patients went home and 19 (10.4%) of 182 patients went to a rehabilitation center. After open surgery, 187 (68.2%) of 274 patients went home and 64 (23.4%) of 274 patients went to a rehabilitation center. The odds ratio of discharge to a rehabilitation center, instead of home, following endovascular procedures versus open surgery was 0.23 (95% CI: 0.13, 0.43). CONCLUSION: Following elective repair of infrarenal abdominal aortic aneurysm, significantly more patients went home after an endovascular procedure than after open surgery. Procedure type was a significant predictor of discharge destination.

CT colonography with teleradiology: effect of lossy wavelet compression on polyp detection--initial observations.

PURPOSE: To assess the consequences of lossy compression on the diagnostic accuracy of CT colonography for detecting colonic polyps. MATERIALS AND METHODS: Helical CT images of cleansed colonic segments were evaluated. Source images were compressed to 1:1, 10:1, and 20:1 ratios with lossy wavelet compression. Two independent readers blinded to corresponding colonoscopic results analyzed 144 randomly ordered colonic segments in multiplanar and volume-rendered endoscopic views. Sensitivity, specificity, and receiver operating characteristic curves were generated for each compression ratio on the basis of expressed confidence in lesion presence. Similar analyses were performed to assess distention and bowel preparation adequacy and evaluation time required. RESULTS: Results based on video colonoscopy-confirmed lesions revealed 100% (four of four) sensitivity for lesions larger than 10 mm for compression ratios 1:1, 10:1, and 20:1 for both readers; sensitivities for all lesions smaller than 10 mm were 50%-78%, 38%-67%, and 38%-67% for respective ratios for both readers. Differences in diagnostic performance for each reader across ratios were not significant (P =.30-.99, McNemar test). The time required to evaluate and assess bowel preparation and distention adequacy did not change significantly across ratios. CONCLUSION: On the basis of the patient sample, lossy compression of transverse source images to at least a 20:1 ratio did not adversely affect diagnostic performance or evaluation time for CT colonography.

Percutaneous tumor ablation: increased necrosis with combined radio-frequency ablation and intratumoral doxorubicin injection in a rat breast tumor model.

PURPOSE: To determine whether a combination of intratumoral doxorubicin injection and radio-frequency (RF) ablation increases tumor destruction compared with RF ablation alone in an animal tumor model. MATERIALS AND METHODS: R3230 mammary adenocarcinoma 1.2-1.5-cm- diameter nodules (n = 110) were implanted subcutaneously in 84 female Fischer rats. For initial experiments (n = 46), tumors were treated with (a) conventional, monopolar RF (250 mA +/- 25 [SD] at 70 degrees C +/- 1 for 5 minutes) ablation alone; (b) direct intratumoral doxorubicin injection (volume, 250 microL; total dose, 0.5 mg) alone; (c) combined therapy (doxorubicin injection immediately followed by RF ablation); (d) RF ablation and injection of 250 microL of distilled water; or (e) no treatment. In subsequent experiments, amount of doxorubicin (0.02-2.50 mg; n = 40 additional tumors) and timing of doxorubicin administration (2 days before to 2 days after RF ablation; n = 24 more tumors) were varied. Pathologic examination, including staining for mitochondrial enzyme activity and perfusion, was performed, and the resultant tumor destruction from each treatment was evaluated. RESULTS: Coagulation diameter was 6.7 mm +/- 0.6 for tumors treated with RF ablation alone and 6.9 mm +/- 0.7 for those treated with RF ablation and water (P =.52), while intratumoral doxorubicin injection alone produced only 2.0-3.0 mm of coagulation (P <.001). Increased coagulation was observed only with combined doxorubicin injection and RF therapy (P <.001). Coagulation was dependent on concentration and timing of doxorubicin administration, with greatest coagulation (11.5 mm +/- 1.1) observed for doxorubicin administered within 30 minutes of RF ablation. CONCLUSION: Adjuvant intratumoral doxorubicin injection increases coagulation in solid tumors compared with RF ablation alone. Increased tumor destruction is also seen when doxorubicin is administered after RF ablation, which suggests that RF ablation may sensitize tumors to chemotherapy. Such combination therapies may, therefore, offer improved methods for ablating solid tumors.

Hospital costs for elective endovascular and surgical repairs of infrarenal abdominal aortic aneurysms.

PURPOSE: To determine and compare the average in-hospital costs of elective open surgical and endovascular repairs of infrarenal abdominal aortic aneurysms. MATERIALS AND METHODS: Total actual cost data for patients undergoing elective endovascular (n = 181) or open surgical (n = 273) repair of abdominal aortic aneurysms between 1997 and 1999 were retrieved. The mean total hospital cost (including stent-graft costs and excluding attending physician fees) and mean postoperative length of stay were calculated for each treatment group. Costs were expressed in 1999 U.S. dollars. RESULTS: Endovascular repair yielded a shorter postoperative length of stay than did open surgery (mean stay, 3.4 vs 8.0 days; P <.001) and a lower proportion of patients who were admitted to the intensive care unit for 1 full day or longer (2.8% vs 36.3%; P <.001). The mean total hospital cost was significantly higher for endovascular repair than for open surgery ($20,716 vs $18,484; P <.001). CONCLUSION: Hospital costs were higher for endovascular repair than for open surgical repair. However, endovascular repair was associated with a decreased length of stay and fewer intensive care unit admissions. The increased mean hospital cost for endovascular repair was smaller than one would expect, considering the higher costs of endovascular grafts, as compared with those for surgical grafts (approximately $6,400 according to literature data).

Inpatient costs of routine endovascular repair of abdominal aortic aneurysm.

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the inpatient cost of routine (ie, without emergent conversion to open repair during the hospital stay) endovascular stent-graft placement in a consecutive series of patients undergoing elective endovascular repair of abdominal aortic aneurysm (AAA) at a single institution. MATERIALS AND METHODS: Inpatient hospital costs of 91 patients who underwent initial elective endovascular repair of AAA were analyzed retrospectively. All patients had participated in clinical trials at the authors' institution during the previous 6 years. Financial data were derived from the hospital's cost-accounting system; additional procedural data were collected from a departmental database and with chart review. Stent-graft and professional costs were excluded. RESULTS: The mean total cost for endovascular repair was $11,842 (standard deviation [SD], $5,127), mean procedure time was 149 minutes (SD, 79 minutes), and mean length of stay was 3.5 days (SD, 2.3 days). Total cost depended on stent-graft type (means, $12,428 [bifurcated] vs $9,622 [tube]; P = .0002) and strongly correlated with procedure time and length of hospital stay (r = 0.78 and 0.66, respectively; P < .0001). Ninety-six percent of total costs for all patients were attributable to the following departments: operating theater (31%), radiology (31%), nursing (22%), and anesthesia (12%). CONCLUSION: Overall costs are greater with bifurcated than with tube stent-grafts. Total procedure-related costs are divided relatively equally between the operating theater, the radiology department, and the combination of the nursing and anesthesia departments.

Percutaneous radio-frequency ablation of liver metastases from breast cancer: initial experience in 24 patients.

PURPOSE: To evaluate the authors' initial experience in a consecutive series of 24 patients with breast cancer liver metastases treated with radio-frequency (RF) ablation. MATERIALS AND METHODS: Twenty-four consecutive patients with 64 metastases measuring 1.0--6.6 cm in diameter (mean, 1.9 cm) underwent ultrasonography-guided percutaneous RF ablation with 18-gauge, internally cooled electrodes. Treatment was performed with the patient under conscious sedation and analgesia or general anesthesia. A single lesion was treated in 16 patients, and multiple lesions were treated in eight patients. Follow-up with serial computed tomography ranged from 4 to 44 months (mean, 10 months; median, 19 months). RESULTS: Complete necrosis was achieved in 59 (92%) of 64 lesions. Among the 59 lesions, complete necrosis required a single treatment session in 58 lesions (92%) and two treatment sessions in one lesion (2%). In 14 (58%) of 24 patients, new metastases developed during follow-up. Ten (71%) of these 14 patients developed new liver metastases. Currently, 10 (63%) of 16 patients whose lesions were initially confined to the liver are free of disease. One patient died of progressive brain metastases. No major complications occurred. Two minor complications were observed. CONCLUSION: On the basis of preliminary study results, percutaneous RF ablation appears to be a simple, safe, and effective treatment for focal liver metastases in selected patients with breast cancer.

Radiofrequency tissue ablation: physical principles and techniques for increasing coagulation necrosis.

Radiofrequency tumor ablation has been demonstrated as a reliable method for creating thermally-induced coagulation necrosis using either a percutaneous approach with image-guidance or direct surgical placement of thin electrodes into tissues to be treated. Early clinical trials with this technology have studied the treatment of hepatic, cerebral, and bony malignancies. The extent of coagulation necrosis induced with conventional monopolar radiofrequency electrodes is dependent on overall energy deposition, the duration of radiofrequency application, and radiofrequency electrode tip length and gauge. This article will discuss these technical considerations with the goal of defining optimal parameters for radiofrequency ablation. Strategies to further increase induced coagulation necrosis including: multiprobe and bipolar arrays, and internally-cooled radiofrequency electrodes, with or without pulsed-radiofrequency or cluster technique will be presented. The development and laboratory results for many of these radiofrequency techniques and potential biophysical limitations to radiofrequency induced coagulation, such as perfusion mediated tissue cooling (vascular flow) will likewise be discussed.

Cost-effectiveness of colorectal cancer screening.

PURPOSE: To determine the most cost-effective colorectal cancer screening strategy costing less than $100,000 per life-year saved and to determine how available strategies compare with each other. MATERIALS AND METHODS: Standardized methods were used to calculate incremental cost-effectiveness ratios (ICERs) from published estimates of cost and effectiveness of colorectal cancer screening strategies, and the direction and magnitude of any effect on the ratio from parameter estimate adjustments based on literature values were estimated. RESULTS: Strategies in which double-contrast barium enema examination was performed emerged as optimal from all studies included. In average-risk individuals, screening with double-contrast barium enema examination every 3 years, or every 5 years with annual fecal occult blood testing, had an ICER of less than $55,600 per life-year saved. However, double-contrast barium enema examination screening every 3 years plus annual fecal occult blood testing had an ICER of more than $100,000 per life-year saved. Colonoscopic screening had an ICER of more than $100,000 per life-year saved, was dominated by other screening strategies, and offered less benefit than did double-contrast barium enema examination screening. CONCLUSION: Double-contrast barium enema examination can be a cost-effective component of colorectal cancer screening, but further modeling efforts are necessary.

Radio-frequency thermal ablation with NaCl solution injection: effect of electrical conductivity on tissue heating and coagulation-phantom and porcine liver study.

PURPOSE: To characterize the effects of NaCl concentration on tissue electrical conductivity, radio-frequency (RF) deposition, and heating in phantoms and optimize adjunctive NaCl solution injection for RF ablation in an in vivo model. MATERIALS AND METHODS: RF was applied for 12-15 minutes with internally cooled electrodes. For phantom experiments (n = 51), the NaCl concentration in standardized 5% agar was varied (0%-25.0%). A nonlinear simplex optimization strategy was then used in normal porcine liver (n = 44) to determine optimal pre-RF NaCl solution injection parameters (concentration, 0%-38.5%; volume, 0-25 mL). NaCl concentration and tissue conductivity were correlated with RF energy deposition, tissue heating, and induced coagulation. RESULTS: NaCl concentration had significant but nonlinear effects on electrical conductivity, RF deposition, and heating of agar phantoms (P<.01). Progressively greater heating was observed to 5.0% NaCl, with reduced temperatures at higher concentrations. For in vivo liver, NaCl solution volume and concentration significantly influenced both tissue heating and coagulation (P<.001). Maximum heating 20 mm from the electrode (102.9 degrees C +/- 4.3 [SD]) and coagulation (7.1 cm +/- 1.1) occurred with injection of 6 mL of 38.5% (saturated) NaCl solution. CONCLUSION: Injection of NaCl solution before RF ablation can increase energy deposition, tissue heating, and induced coagulation, which will likely benefit clinical RF ablation. In normal well-perfused liver, maximum coagulation (7.0 cm) occurs with injection of small volumes of saturated NaCl solution.