Acute Nonhemorrhagic Adrenal Infarction in Pregnancy: 10-Year MRI Incidence and Patient Outcomes at a Single Institution.

OBJECTIVE: The purpose of this study was to retrospectively investigate the MRI incidence of nonhemorrhagic adrenal infarction in pregnant women undergoing MRI evaluation of acute abdominal or flank pain, assess the MRI features quantitatively, and report patient outcomes. MATERIALS AND METHODS: All abdominal MRI examinations of pregnant women with acute pain at one institution from May 2005 to April 2015 were reviewed. The adrenals were evaluated for abnormal morphologic and signal intensity characteristics described in the literature characterizing nonhemorrhagic adrenal infarction and were compared with the contralateral adrenal by paired t tests. The findings were correlated with clinical presentation. Patient demographics and outcomes were gathered from the medical record. RESULTS: Findings of nonhemorrhagic adrenal infarction were present in 5 of 379 (1.3%) examinations of four pregnant patients (mean age, 28 years; range, 20.8-33.9 years; mean gestational age, 26 weeks; range, 16-35 weeks). MRI features included lengthening (mean, 39.8 versus 21.2 mm) (p = 0.005) and increased T2 signal intensity (p = 0.001) of the infarcted adrenal with surrounding edema and without T1 signal intensity suggesting hemorrhage. No alternative diagnosis was identified. All patients presented with severe acute abdominal or flank pain on the same side as the MRI findings, tenderness to palpation, and mild leukocytosis. All women delivered healthy infants. CONCLUSION: Unilateral nonhemorrhagic adrenal infarction was identified in 1.3% of abdominal MRI examinations performed for pregnant women with acute abdominal or flank pain. Knowledge of the MRI characteristics of this entity is important for recognizing it and may prevent further potentially invasive tests, procedures, or missed diagnoses.

Percutaneous Image-Guided Cryoablation of Hepatic Tumors: Single-Center Experience With Intermediate to Long-Term Outcomes.

OBJECTIVE: The purpose of this article is to report our intermediate to long-term outcomes with image-guided percutaneous hepatic tumor cryoablation and to evaluate its technical success, technique efficacy, local tumor progression, and adverse event rate. MATERIALS AND METHODS: Between 1998 and 2014, 299 hepatic tumors (243 metastases and 56 primary tumors; mean diameter, 2.5 cm; median diameter, 2.2 cm; range, 0.3-7.8 cm) in 186 patients (95 women; mean age, 60.9 years; range, 29-88 years) underwent cryoablation during 236 procedures using CT (n = 126), MRI (n = 100), or PET/CT (n = 10) guidance. Technical success, technique efficacy at 3 months, local tumor progression (mean follow-up, 2.5 years; range, 2 months to 14.6 years), and adverse event rates were calculated. RESULTS: The technical success rate was 94.6% (279/295). The technique efficacy rate was 89.5% (231/258) and was greater for tumors smaller than 4 cm (93.4%; 213/228) than for larger tumors (60.0%; 18/30) (p < 0.0001). Local tumor progression occurred in 23.3% (60/258) of tumors and was significantly more common after the treatment of tumors 4 cm or larger (63.3%; 19/30) compared with smaller tumors (18.0%; 41/228) (p < 0.0001). Adverse events followed 33.8% (80/236) of procedures and were grade 3-5 in 10.6% (25/236) of cases. Grade 3 or greater adverse events more commonly followed the treatment of larger tumors (19.5%; 8/41) compared with smaller tumors (8.7%; 17/195) (p = 0.04). CONCLUSION: Image-guided percutaneous cryoablation of hepatic tumors is efficacious; however, tumors smaller than 4 cm are more likely to be treated successfully and without an adverse event.

Hepatic Microwave Ablation Zone Size: Correlation with Total Energy, Net Energy, and Manufacturer-Provided Chart Predictions.

PURPOSE: To determine whether total energy (TE) reaching the microwave (MW) applicator or net energy (NE) exiting the applicator (after correcting for reflectivity) correlates better with hepatic MW ablation zone dimensions than manufacturer-provided chart predictions. MATERIALS AND METHODS: Single-applicator, nonoverlapping ablations of 93 liver tumors (0.7-5.9 cm) were performed in 52 adult patients. TE and NE were recorded for each ablation. Long axis diameter (LAD), short axis diameter (SAD), and volume (V) of each ablation zone were measured on magnetic resonance imaging or computed tomography after the procedure and retrospectively compared with TE; NE; and manufacturer-provided chart predictions of LAD, SAD, and V using correlation and regression analyses. RESULTS: For treated tumors, mean (± SD) TE and NE were 49.8 kJ (± 22.7) and 36.4 kJ (± 19.4). Mean LAD, SAD, and V were 5.8 cm (± 1.3), 3.7 cm (± 0.8), and 44.1 cm(3) (± 25.4). Correlation coefficients (95% confidence interval) with LAD, SAD, and V were 0.46 (0.28, 0.61), 0.52 (0.36, 0.66), and 0.52 (0.36, 0.66) for TE; 0.42 (0.24, 0.58), 0.55 (0.39, 0.68), and 0.53 (0.36, 0.66) for NE; and 0.51 (0.34, 0.65), 0.63 (0.49, 0.74), and 0.60 (0.45, 0.73) for chart predictions. Using regression analysis and controlling for TE, SAD was 0.34 cm larger in patients with cirrhosis than in patients without cirrhosis. CONCLUSIONS: Correcting for reflectivity did not substantially improve correlation of energy values with MW ablation zone size parameters and did not outperform manufacturer-provided chart predictions. Correlations were moderate and variable using all methods. The results suggest a disproportionate influence of tissue factors on MW ablation results.

Catecholamine Surge during Image-Guided Ablation of Adrenal Gland Metastases: Predictors, Consequences, and Recommendations for Management.

PURPOSE: To identify retrospectively predictors of catecholamine surge during image-guided ablation of metastases to the adrenal gland. MATERIALS AND METHODS: Between 2001 and 2014, 57 patients (39 men, 18 women; mean age, 65 y ± 10; age range, 41-81 y) at two academic medical centers underwent ablation of 64 metastatic adrenal tumors from renal cell carcinoma (n = 27), lung cancer (n = 23), melanoma (n = 4), colorectal cancer (n = 3), and other tumors (n = 7). Tumors measured 0.7-11.3 cm (mean, 4 cm ± 2.5). Modalities included cryoablation (n = 38), radiofrequency (RF) ablation (n = 20), RF ablation with injection of dehydrated ethanol (n = 10), and microwave ablation (n = 4). Fisher exact test, univariate, and multivariate logistical regression analysis was used to evaluate factors predicting hypertensive crisis (HC). RESULTS: HC occurred in 31 sessions (43%). Ventricular tachycardia (n = 1), atrial fibrillation (n = 2), and troponin leak (n = 4) developed during HC episodes. HC was significantly associated with maximum tumor diameter ≤ 4.5 cm (odds ratio [OR], 26.36; 95% confidence interval [CI], 5.26-131.99; P < .0001) and visualization of normal adrenal tissue on CT or MR imaging before the procedure (OR, 8.38; 95% CI, 2.67-25.33; P < .0001). No HC occurred during ablation of metastases in previously irradiated or ablated adrenal glands. CONCLUSIONS: Patients at high risk of catecholamine surge during ablation of non-hormonally active adrenal metastases can be identified by the presence of normal adrenal tissue and tumor diameter ≤ 4.5 cm on pre-procedure CT or MR imaging.

Percutaneous cryoablation of hepatic tumors adjacent to the gallbladder: assessment of safety and effectiveness.

PURPOSE: To assess safety and effectiveness of percutaneous image-guided cryoablation of hepatic tumors adjacent to the gallbladder. MATERIALS AND METHODS: Twenty-one cryoablation procedures were performed to treat 19 hepatic tumors (mean size, 2.7 cm; range, 1.0-5.0 cm) adjacent to the gallbladder in 17 patients (11 male; mean age, 59.2 y; range, 40-82 y) under computed tomography (n = 15) or magnetic resonance imaging (n = 6) guidance in a retrospective study. All tumors (mean size, 2.67 cm; range, 1.0-5.0 cm) were within 1 cm (mean, 0.4 cm) of the gallbladder; seven (33%) were contiguous with the gallbladder. Primary outcomes included complication rate and severity and postprocedure gallbladder imaging findings. Secondary outcomes included technical success and technique effectiveness at 6 months. RESULTS: Complications occurred in six of 21 procedures (29%); one (5%) was severe. Ice balls extended into the gallbladder lumen in 20 of 21 procedures (95%); no gallbladder-related complications occurred. The most common gallbladder imaging finding was mild, asymptomatic focal wall thickening after nine of 21 procedures (42%), which resolved on follow-up. Technical success was achieved in 19 of 21 sessions (90%). Six-month follow-up was available for 16 tumors; of these, all but two (87%) had no imaging evidence of local tumor progression. CONCLUSIONS: Percutaneous cryoablation of hepatic tumors adjacent to the gallbladder can be performed safely and successfully. Although postprocedural gallbladder changes are common, they are self-limited and clinically inconsequential, even when the ice ball extends into the gallbladder lumen.

Percutaneous imaging-guided cryoablation of liver tumors: predicting local progression on 24-hour MRI.

OBJECTIVE: The purpose of this study was to determine which MRI features observed 24 hours after technically successful percutaneous cryoablation of liver tumors predict subsequent local tumor progression and to describe the evolution of imaging findings after cryoablation. MATERIALS AND METHODS: Thirty-nine adult patients underwent technically successful imaging-guided percutaneous cryoablation of 54 liver tumors (hepatocellular carcinoma, 8; metastases, 46). MRI features pertaining to the tumor, ablation margin, and surrounding liver 24 hours after treatment were assessed independently by two readers. Fisher exact or Wilcoxon rank sum tests (significant p values < 0.05) were used to compare imaging features in patients with and without subsequent local tumor progression. Imaging features of the ablation margin, treated tumor, and surrounding liver were evaluated on serial MRI in the following year. RESULTS: A minimum ablation margin of 3 mm or less was observed in 11 (78.6%) of 14 tumors with and 15 of 40 (37.5%) without progression (p = 0.012). A blood vessel bridging the ablation margin was noted in 11 of 14 (78.6%) tumors with and nine of 40 (22.5%) without progression (p < 0.001). The incidence of tumor enhancement 24 hours after cryoablation was similar for tumors with (10/14, 71.4%) or without (25/40, 62.5%) local progression (p = 0.75). MRI enabled assessment of the entire cryoablation margin in 49 of 54 (90.7%) treated tumors. CONCLUSION: MRI features at 24 hours after liver cryoablation that were predictive of local tumor progression included a minimum ablation margin less than or equal to 3 mm and a blood vessel bridging the ablation margin. Persistent tumor enhancement is common after liver cryoablation and does not predict local tumor progression.

Contrast-enhanced CT and MR imaging of renal vessels.

In the evaluation of renal vessels, the accepted diagnostic gold standard digital subtraction angiography is now being challenged by state of the art CT and MR imaging. Currently in many centers, cross-sectional imaging modalities are being used as a first line diagnostic tool to evaluate arterial and venous system of the kidneys and conventional angiography has been reserved only for therapeutic intervention. CT and MR imaging display not only the lumen of the vessel as in conventional angiography, but also allow the visualization of the vessel wall, renal parenchyma, collecting system, and other adjacent soft tissue structures. Therefore, CT and MRI have each become a one-stop shop for a thorough evaluation of kidneys. In this pictorial essay, we reviewed normal anatomical variants and wide range of pathologies involving renal arteries and veins with illustrated contrast-enhanced CT and MR imaging samples.

Renal transplant complications: diagnostic and therapeutic role of radiology.

Kidney was the first and is the most frequently transplanted organ. Despite improved surgical techniques and transplantation technology, complications do occur and, if left untreated, may lead to catastrophic consequences. Renal transplantation complications may be vascular (eg, renal artery and vein stenosis and thrombosis, arteriovenous fistula, and pseudoaneurysms); urologic (eg, urinary obstruction and leak, and peritransplantation fluid collections, including hematoma, seroma, lymphocele, and abscess formation); and nephrogenic, including acute tubular necrosis, graft rejection, chronic allograft nephropathy, and neoplasm. Early diagnosis and treatment of these complications are paramount to prevent graft failure and other significant morbidities to the patients. Radiology plays a pivotal role in the diagnosis and treatment of these complications, with minimally invasive percutaneous techniques. In this article, we reviewed renal transplantation anatomy, a wide range of complications that may occur after renal transplantation surgery, typical imaging appearances of the complications on varies imaging modalities, and percutaneous interventional techniques that are used in their treatment.

MRI assessment of percutaneous ablation of liver tumors: value of subtraction images.

PURPOSE: To evaluate the value of subtraction images when using MRI to assess liver tumors treated with percutaneous ablation. MATERIALS AND METHODS: Following percutaneous ablation of 35 liver tumors, two abdominal radiologists, blinded to outcomes, independently reviewed follow-up MRI examinations for tumoral enhancement suggestive of residual/recurrent tumor and rated their confidence level. After one year, the readers reviewed the same examinations with added subtraction images. Accuracy of the detection of residual/recurrent tumor and contrast-to-noise ratios (CNR; for tumoral enhancement-to-liver, tumoral enhancement-to-ablation zone, and ablation zone-to-liver) were calculated with and without subtraction images and compared using Wilcoxon signed rank test. Interobserver variability was computed using Kappa (κ) statistics. RESULTS: Residual/recurrent tumor was present in 8 (23.5%) of 34 tumors. Accuracy of detecting residual/recurrent tumor with subtraction images and interobserver agreement (κ = 0.72, good) were better than accuracy of detecting residual/recurrent tumor and interobserver agreement (κ = 0.57, moderate) of enhanced MR images without subtraction. Mean CNR of subtraction images was significantly higher than that of enhanced MR images for tumoral enhancement-to-liver (0.2 ± 5 versus 11.6 ± 14.4, P = 0.03), tumoral enhancement-to-ablation zone (10.1 ± 12.5 versus 34.4 ± 29.4, P = 0.02), and ablation zone-to-liver (11.8 ± 13.3 versus 102.5 ± 238.4, P = 0.03). CONCLUSION: When using MRI, subtraction images help both detect and exclude residual/recurrent tumor following percutaneous liver ablations.

Successful percutaneous radiologic management of renal cell carcinoma tumor seeding caused by percutaneous biopsy performed before ablation.

A case is reported of the successful image-based detection, diagnosis, and percutaneous ablation of tumor seeding in a 61-year-old man that was caused by percutaneous biopsy of a renal cell carcinoma performed before cryoablation and was not detected until 4 years after the biopsy procedure. Although tumor seeding is a rare complication after percutaneous biopsy or ablation, this case emphasizes the importance of imaging surveillance of the needle tract used during both biopsy and ablation procedures, provides guidance on measures that can be used to minimize the occurrence of tumor seeding, and demonstrates that entirely radiologic management can be successful.

MRI contrast enhancement of malignant liver tumours following successful cryoablation.

OBJECTIVES: To assess the incidence and degree of MRI contrast enhancement in liver tumours following successful percutaneous cryoablation. METHODS: Thirty-eight patients with liver metastases (n = 29) or hepatocellular carcinoma (n = 9) underwent percutaneous cryoablation of 45 tumours between March 2004 and June 2009, with complete ablation zone coverage of the tumour and no local recurrence on follow-up imaging to date (range 3-60 months, mean 16). Contrast-enhanced MRI was used to assess 45 tumours at 24 h, 32 tumours at 2-4 months, and 21 tumours at 5-7 months. Percentage of tumours with contrast enhancement was assessed using dynamic spoiled gradient echo T1-weighted images. RESULTS: Twenty-four hours post-cryoablation, 23 out of 45 tumours (51%) enhanced compared with 42 out of 43 (98%) pre-ablation (p < 0.001). Mean percentage tumour enhancement decreased from 157% (range 26-745%) pre-ablation, to 107% (27-260%) at 24 h (p = 0.003), and 43% (24-103%) at 2-4 months (p < 0.001). The incidence and degree of tumour enhancement decreased through 5-7 months. CONCLUSIONS: Unlike previously reported studies of radiofrequency ablation, successful cryoablation of liver tumours is often associated with persistent tumour contrast enhancement on MRI performed at 24 h and decreasing over 2-7 months. KEY POINTS: • Liver neoplasms often demonstrate MRI contrast enhancement following successful percutaneous cryoablation. • This differs from radiofrequency ablation techniques where contrast enhancement suggests residual tumour • This difference could potentially lead to important errors in follow up strategies.

Biochemical and hematologic changes after percutaneous radiofrequency ablation of liver tumors: experience in 83 procedures.

PURPOSE: To determine the frequency and severity of various abnormal laboratory tests after percutaneous radiofrequency (RF) ablation of liver tumors and to estimate the correlation between laboratory test values and volumes of tumor and ablated tissue. MATERIALS AND METHODS: Biochemical and hematologic laboratory values of 83 computed tomography-guided RF ablations of liver tumors were reviewed retrospectively at baseline, 0-6, 6-12, 12-24 hours, and 1-2 weeks, assessed for significant changes, and correlated with tumor, total ablation, and ablative margin (consisting of ablated nontumoral liver parenchyma and calculated by subtracting tumor volume from ablation volume). RESULTS: Mean total ablation volume was 26.6 mL (range, 3.14-1020.5 mL). Aspartate aminotransferase (AST) values exceeded normal range after 78 (93.9%) procedures and peaked at 12-24 hours (mean, 321 U/L). Alanine aminotransferase (ALT) values exceeded normal range after 58 (69.9%) procedures and peaked at 12-24 hrs (mean, 220 U/L). Bilirubin levels increased after 34 (41%) procedures (mean maximal increase, 1.1 mg/dL) and peaked at 12-24 hours in 13 (36%). Peak AST (r = 0.3), peak ALT (r = 0.3), and peak bilirubin (r = 0.3) levels correlated only with ablation margin volume. Three patients with severely elevated bilirubin and alkaline phosphatase levels had biliary complications. Platelets decreased below 100,000/µL (n = 5) only when the preprocedural level was < 120,000/µL. Severe myoglobinemia occurred once and was treated successfully with serum alkalinization. CONCLUSIONS: Changes in laboratory values after percutaneous RF ablation of liver tumors are common and usually mild and self-limited. Peak aminotranferase levels and bilirubin values correlate with ablative margin volume and, along with elevated alkaline phosphatase, when severe, may be a harbinger of biliary complications.

PET/CT-guided percutaneous biopsy of abdominal masses: initial experience.

PURPOSE: To develop a technique for guiding percutaneous biopsies of abdominal masses in a positron emission tomography (PET)/computed tomography (CT) scanner, and test its feasibility and safety in patients. MATERIALS AND METHODS: The authors conducted a prospective study in 12 patients who were in need of both a diagnostic (18)F-fluoro-deoxy-D-glucose (FDG) PET/CT scan and a percutaneous biopsy of an abdominal mass, located in the liver (n = 7), presacral soft tissue (n = 2), lymph node (n = 2), and kidney (n = 1). After completion of the PET/CT scan, with the patient remaining on the table, a one-table-position PET/CT scan was obtained with a radiopaque grid in place, and the biopsy procedure was planned. Then, a biopsy needle was placed into the mass using one-table-position CT scan registered to the planning PET scan. Masses were sampled after confirming accurate positioning of the needle tips with a final one-table-position PET/CT scan. Negative results were confirmed independently with follow-up imaging. RESULTS: All biopsy procedures yielded diagnostic results; nine were positive for malignancy, and three were negative (fibrosis, steatosis, and Escherichia coli infection). One non-FDG-avid mass biopsy yielded a malignant result. Seven masses were either invisible or poorly depicted with unenhanced CT scan, and two masses contained FDG avidity in only a portion of the mass. There were no complications. CONCLUSIONS: Although our data are preliminary, this initial experience suggests that abdominal masses can undergo successful biopsy in a PET/CT scanner. PET/CT guidance may be helpful when performing biopsy on FDG-avid masses that are either not visible with unenhanced CT or are FDG avid in only a portion.

PET/CT-guided radiofrequency and cryoablation: is tumor fluorine-18 fluorodeoxyglucose activity dissipated by thermal ablation?

PURPOSE: To determine if tumor fluorine-18 fluorodeoxyglucose ((18)F-FDG) activity is dissipated by radiofrequency (RF) ablation or cryoablation during tumor ablation guided by positron emission tomography/computed tomography (PET/CT). MATERIALS AND METHODS: This prospective study enrolled 12 patients (9 women and 3 men, 39-65 years old), each with at least one (18)F-FDG-avid liver, perihepatic, or lung tumor. Six patients (experimental group) underwent percutaneous PET/CT-guided RF ablation (n = 3) or cryoablation (n = 3). Six patients (control group) underwent diagnostic PET/CT-guided percutaneous biopsy. At a mean time of 103.5 minutes after a single intravenous (18)F-FDG dose, preprocedure and postprocedure PET/CT scans, separated by a mean time interval of 83.4 minutes, were obtained in all patients. Target tumor maximum standardized uptake value (TSUVmax) and ratio (SUVratio) of TSUVmax to normal liver average standardized uptake value (LSUVavg) were measured on all scans. Percentage changes in TSUVmax and SUVratio from preprocedure to postprocedure scans were compared for both groups and analyzed using the Student t test (P < .05 considered statistically significant). RESULTS: For all patients in both groups, TSUVmax and SUVratio increased from preprocedure to postprocedure PET/CT scans without statistically significant differences. The mean percentage increase in TSUVmax for the ablation group was 32.5% (range 8.2%-46.7%) and for the biopsy group was 24.6% (3.7%-42.4%; P = .45). The mean percentage increase in SUVratio for the ablation group was 47.9% (18.8%-69.6%) and for the biopsy group was 37.6% (9.4%-65%; P = .37). CONCLUSIONS: Tumor (18)F-FDG activity is not dissipated by percutaneous RF ablation or cryoablation. When performing (18)F-FDG PET/CT-guided RF ablation or cryoablation, changes in target tumor (18)F-FDG activity cannot be used to monitor treatment effects.

Minimizing image misregistration during PET/CT-guided percutaneous interventions with monitored breath-hold PET and CT acquisitions.

PURPOSE: To validate a monitored, breath-hold positron emission tomography (PET)/computed tomography (CT) acquisition technique for the minimization of respiratory PET/CT image misregistration and lesion distortion during PET/CT-guided percutaneous interventional procedures. MATERIALS AND METHODS: Eleven patients referred for percutaneous biopsy or thermal ablation of tumors near the diaphragm were prospectively enrolled. Initial PET/CT scanning was performed by using a bellows device and monitored, same-level breath-holds for PET and CT acquisitions. Breath-hold PET consisted of nine 20-second breath-hold frames, yielding a 3-minute equivalent PET dataset. A second PET/CT scan was obtained without monitoring by using end-expiration breath-hold CT and free-breathing PET. PET/CT tumor misregistration and craniocaudal tumor diameter were measured on monitored and unmonitored PET/CT datasets. Data were analyzed by using nonparametric, two-sided, signed-rank statistical tests. RESULTS: Mean PET/CT image misregistrations in the craniocaudal, anteroposterior, and transverse planes were 2.6 mm (range, 0-7 mm), 3.3 mm (range, 1-8 mm), and 2.7 mm (range, 0-8 mm) with monitoring and 14.7 mm (range, 0-49 mm), 7.6 mm (range, 1-24 mm), and 4.0 mm (range, 0-12 mm) without monitoring, respectively. Differences were significant for craniocaudal (P = .0087) and anteroposterior (P = .014) planes, but not for the transverse plane (P = .23). Mean craniocaudal target diameter was 2.5 mm (range, -2 to 9 mm) larger (ie, distorted) for unmonitored versus monitored PET (P = .061). CONCLUSIONS: Acquiring PET/CT datasets with respiratory bellows-assisted, monitored breath-holds improves PET/CT image registration versus unmonitored PET/CT and may facilitate accurate targeting during PET/CT-guided interventions in anatomic regions subject to respiratory motion.

Abdominal masses sampled at PET/CT-guided percutaneous biopsy: initial experience with registration of prior PET/CT images.

PURPOSE: To establish the feasibility of performing combined positron emission tomography (PET)/computed tomography (CT)-guided biopsy of abdominal masses by using previously acquired PET/CT images registered with intraprocedural CT images. MATERIALS AND METHODS: In this HIPAA-compliant institutional review board-approved study, 14 patients underwent clinically indicated percutaneous biopsy of abdominal masses (mean size, 3.3 cm; range, 1.2-5.0 cm) in the liver (n = 6), presacral soft tissue (n = 3), retroperitoneal lymph nodes (n = 2), spleen (n = 2), and pancreas (n = 1). PET/CT images obtained no more than 62 days (mean, 18.3 days) before the biopsy procedure were registered with intraprocedural CT images by using image registration software. The registered images were used to plan the procedure and help target the masses. RESULTS: The image registrations were technically successful in all but one patient, who had severe scoliosis. The remaining 13 biopsy procedures yielded diagnostic results, which were positive for malignancy in 10 cases and negative in three cases. CONCLUSION: PET/CT-guided abdominal biopsy with use of prior PET/CT images registered with intraprocedural CT scans is feasible and may be helpful when fluorine 18 fluorodeoxyglucose-avid masses that are not seen sufficiently with nonenhanced CT are sampled at biopsy.

Short pancreas: evaluation with multi-detector row CT.

PURPOSE: The purpose of this study was to analyze the length variations of the pancreas using computed tomography (CT) and establish a database for short pancreas. METHODS: We retrospectively reviewed CT examinations of 228 adults and rated pancreatic lengths qualitatively on a scale of 1-3 using transverse images. 1, normal pancreas length; 2, mildly short pancreas; and 3, markedly short pancreas. The length of the pancreas from head to tail was also measured using the "curved line tool" through the midline of the organ on curved planar reconstructed (CPR) images. The pancreatic neck-tail length and the abdominal radius were measured on transverse images, and the ratio of pancreatic neck-tail length to abdominal radius was calculated to avoid the effect of body mass differences. All data were analyzed statistically. RESULTS: The pancreas length was normal (group 1) in 180 (78.9%) patients, mildly short (group 2) in 38 (16.7%), and markedly short (group 3) in 10 (4.4%). The average pancreatic length on CPR evaluation was 207.5 ± 19.1 mm in group 1, 168.9 ± 8.5 mm in group 2, and 135.1 ± 10.7 mm in group 3. There were statistically significant differences between three groups. Although it was not statistically significant, percentage of diabetes mellitus was higher in group 3 (20%) than other two groups (13.2% in group 2, and 8.9% in group 1). CONCLUSIONS: CT examination of the pancreas is an effective imaging method to classify the pancreatic length and to detect short pancreas. We suggest that pancreatic length variations should be reported on routine abdominal CT examinations.

Imaging findings during and after percutaneous cryoablation of hepatic tumors.

OBJECTIVE: Imaging plays a key role in the assessment of patients before, during, and after percutaneous cryoablation of hepatic tumors. Intra-procedural and early post-procedure imaging with CT and MRI is vital to the assessment of technical success including adequacy of ablation zone coverage. Recognition of the normal expected post-procedure findings of hepatic cryoablation such as ice ball formation, hydrodissection, and the normal appearance of the ablation zone is crucial to be able to differentiate from complications including vascular, biliary, or non-target organ injury. Delayed imaging is essential for determination of clinical effectiveness and detection of unexpected findings such as residual unablated tumor and local tumor progression. The purpose of this article is to review the spectrum of expected and unexpected imaging findings that may occur during or after percutaneous cryoablation of hepatic tumors. CONCLUSION: Differentiating expected from unexpected findings during and after hepatic cryoablation helps radiologists identify residual or recurrent tumor and detect procedure-related complications.

Comparison of percutaneous and surgical approaches to renal tumor ablation: metaanalysis of effectiveness and complication rates.

PURPOSE: To determine the effectiveness and complication rates of ablation of renal cell carcinoma (RCC) performed with a percutaneous approach versus a surgical approach. MATERIALS AND METHODS: A search performed on PubMed identified series of renal tumor ablations. Keywords searched included "radiofrequency" (RF), "cryoablation", "cryosurgery", "cryotherapy", "ablation", "renal", "kidney", and "RCC". Review articles were excluded from the search of English-language literature from January 1996 through August 2006. Inclusion criteria were (i) more than one case, (ii) use of RF ablation or cryoablation, (iii) effectiveness based on follow-up imaging, and (iv) report of complication rate. Effectiveness was defined by the proportion of tumors without residual enhancement after one treatment session (ie, primary effectiveness) or after repeated treatments (ie, secondary effectiveness). Major complications were defined as events with substantial morbidity, disability, or increasing level of care. Metaanalysis was performed on primary effectiveness, secondary effectiveness, and major complication rates with a random-effects model. Differences were considered significant if the 95% CIs did not overlap. RESULTS: Forty-six series (28 percutaneous, 18 surgical) met all inclusion criteria. The primary effectiveness rate for the percutaneous group (87%) was significantly lower than that in the surgical group (94%; P < .05). The secondary effectiveness rate in the percutaneous treatment group (92%) was not significantly different from that in the surgical treatment group (95%; P > .05). The major complication rate in the percutaneous treatment group (3%) was significantly lower than that in the surgical treatment group (7%; P < .05). CONCLUSIONS: Based on a metaanalysis, when ablating renal tumors, a percutaneous approach was safer than an open or laparoscopic approach and was equally effective. However, more than one procedure was needed to treat the tumor completely.