Differentiating malignant from benign common bile duct stricture with multiphasic helical CT

PURPOSE: To evaluate retrospectively the use of multiphasic helical computed tomography (CT) to differentiate malignant and benign common bile duct (CBD) strictures in patients with only a focal CBD stricture and to determine predictors for this differentiation. MATERIALS AND METHODS: Institutional review board approval and informed patient consent were not required. Fifty patients (35 men, 15 women; age range, 35-87 years; mean age, 61.6 years) with only a focal CBD stricture comprised the sample for this study (32 malignant and 18 benign strictures). The diagnosis of all malignant and five benign CBD strictures was confirmed by reviewing patients' surgical and pathology records; in 13 benign CBD strictures, the diagnosis was confirmed by means of clinical features. Multiphasic CT findings were analyzed with regard to the wall thickness, location, length, and enhancement pattern of the involved CBD, the upstream CBD diameter, and other findings. CT features to identify benign and malignant CBD strictures were compared by means of univariate analysis and multivariable stepwise logistic regression analysis. RESULTS: Malignant strictures were longer (17.9 mm +/- 6.6 [+/- standard deviation]) than benign strictures (8.9 mm +/- 6.8) (P < .0001), and upstream CBD diameters were larger in malignant cases (22.0 mm +/- 5.4) than in benign cases (17.8 mm +/- 4.6) (P = .033). The involved wall thickness was more than 1.5 mm in 26 malignant cases and three benign cases (P < .0001). During both hepatic arterial and portal venous phases, greater enhancement than that in the normal CBD were more frequently observed in malignant cases (in 27 and 30 patients for hepatic arterial and portal venous phase scans, respectively) than in benign cases (in two and three patients, respectively) (P < .0001). Results of multivariable stepwise logistic regression analysis showed that hyperenhancement of the involved CBD during the portal venous phase was the only variable that could be used to independently differentiate malignant from benign strictures. CONCLUSION: Hyperenhancement of the involved CBD during the portal venous phase is the main factor distinguishing malignant from benign CBD strictures.     

Renal cell carcinoma: analysis of postoperative recurrence patterns

PURPOSE: To retrospectively analyze the recurrence patterns of renal cell carcinoma (RCC) and the factors affecting tumor recurrence. MATERIALS AND METHODS: The institutional review board approved this study; patient informed consent was not required. There were 162 men (mean age, 54 years +/- 13 [standard deviation]) and 32 women (mean age, 56 years +/- 11) who had undergone complete surgical resection of RCC. Mean follow-up period was 45 months (range, 7-92 months). In consensus, two radiologists determined the presence or absence of tumor recurrence and recorded the time and sites of tumor recurrence. The relationships between tumor recurrence and tumor factors, including greatest diameter (> or =5 cm or <5 cm), T stage, N stage, stage group, histologic subtype, and nuclear grade, were evaluated by using Kaplan-Meier statistics. RESULTS: Tumor recurred in 41 (21%) patients. The mean time of tumor recurrence was 17 months (range, 3-50 months). Tumor recurred within 2 years after surgery in 34 (83%) patients. Tumor recurrence sites included lung (n = 29), bone (n = 13), the nephrectomy site (n = 7), brain (n = 6), liver (n = 5), mediastinal lymph nodes (n = 5), the contralateral kidney (n = 4), and the neck muscles (n = 2). The recurrence rate was greater for tumors 5 cm or larger than for those smaller than 5 cm, greater for T3a or T3b tumors than for T1 tumors, greater for stage III tumors than for stage I tumors, and greater for tumors with a nuclear grade of 3 or 4 than for those with a nuclear grade of 1 or 2 (P < .05 for all). CONCLUSION: RCC usually recurs within 2 years after surgery, with the lung being the most vulnerable site; greatest tumor diameter, T stage, stage group, and nuclear grade are important factors for recurrence.     

Ex Vivo Experiment of Saline-Enhanced Hepatic Bipolar Radiofrequency Ablation with a Perfused Needle Electrode: Comparison with Conventional Monopolar and Simultaneous Monopolar Modes

The purpose of this study was to validate the saline-enhanced bipolar radiofrequency ablation (RFA) technique using a perfused electrode to increase RF-created coagulation necrosis, to compare that technique with monopolar RFAs and to find appropriate concentrations and volumes of perfused NaCl solution for the bipolar RFA. A total of 90 ablations were performed in explanted bovine livers. In the initial experiments to determine appropriate conditions for bipolar RFA, we created five thermal ablation zones in each condition, with instillations of varied concentrations (0.9–36%) or injection rates (30 mL/hr–120 mL/hr) of NaCl solution. After placement of one or two 16-gauge open-perfused electrodes into bovine livers, the NaCl solution was instilled into the tissue through the electrode. In the second part of the study, 10 ablation zones were created using one or two perfused electrodes for each of five groups under different conditions: a conventional monopolar mode with 0.9% NaCl solution (group A) or with 6% NaCl solution (group B), a simultaneous monopolar mode with 6% NaCl solution (group C) and a bipolar mode with 6% NaCl solution (groups D and E). RF was applied to each electrode for 20 min in groups A, B, C, and E, or for 10 min in group D. During RFA, we measured the tissue temperature 15 mm from the electrode. The temperature changes during the RFA and the dimensions of the ablation zones were compared among the groups. Bipolar RFA created larger short-axis diameters of coagulation necrosis with 6% NaCl solution (35.8 ± 15 mm) than with 0.9% NaCl solution (17 ± 9.7 mm) (P < 0.05). However, concentrations of NaCl solution above 6% did not further increase the extent of coagulation necrosis. In addition, bipolar RFA with 6% NaCl solution instillation at a rate of 1.0 mL/min (37.9 ± 5.4 mm) or 2.0 mL/min (35.6 ± 9.3 mm) produced larger diameters at the mid-point between the electrodes of the ablated lesion than did 0.5 mL/min (25.8 ± 9.3 mm) (P < 0.05). The bipolar mode showed a more rapid increase in temperature at the mid-point between the two probes, up to 60°C, than did the monopolar modes (P < 0.05). In addition, the bipolar RFA (group E) treated for 20 min showed a larger value of the short-axis diameter than did the conventional or simultaneous monopolar modes (P < 0.05), and bipolar RFA (group D) treated for 10 min, showed similar results with conventional monopolar modes treated for 20 min (P > 0.05): 31.0 ± 5.4 mm (group A); 28.8 ± 3.8 mm (group B); 25.5 ± 6.4 mm (group C); 32.6 ± 4.2 mm (group D); 49.4 ± 5.0 mm (group E). Bipolar RFA with instillation of 6% NaCl solution through an open perfusion system demonstrates better efficacy in creating a larger ablation zone than does conventional or simultaneous monopolar modes at the various times examined. Therefore, hypertonic saline-enhanced bipolar RFA seems to be a promising approach for treating larger liver tumors.     

Functional heterogeneity of the supplementary motor area

BACKGROUND AND PURPOSE: The purpose of this study was to assess supplementary motor area (SMA) activation during motor, sensory, word generation, listening comprehension, and working memory tasks by using functional MR imaging (fMRI). Human supplementary motor area (SMA) has been shown to play roles in motor control and other various functions such as sensory, speech expression, and memory. However, topographical localizations of these functions in the SMA remain unclear. The purpose of this study was to assess SMA activation during motor, sensory, word generation, listening comprehension, and working memory tasks by using functional MR imaging (fMRI). METHODS: Sixteen healthy right-handed subjects (nine men and seven women) were imaged on a Siemens 1.5T system. Whole-brain functional maps were acquired by using blood oxygenation level-dependent echo-planar imaging sequences in the axial plane. Each paradigm consisted of five epochs of activation versus the control condition. The activation tasks consisted of left-finger complex movement, heat sensory stimulation of the left hand, word generation, listening comprehension, and working memory. The reference function was a boxcar waveform. Activation maps were thresholded at an uncorrected P = .0001. The thresholded activation maps were placed into MNI (Montreal Neurologic Institute) stereotactic coordinates, and the anatomic localization of activation within the SMA was compared across tasks. RESULTS: SMA activation was observed in 16 volunteers for the motor task, 11 for the sensory task, 15 for the word generation task, five for the listening comprehension task, and 15 for the working memory task. Although not statistically significant, qualitative differences in the location of activation within the SMA were present by task. The rostral aspects of the SMA tended to activate during word generation and working memory tasks, and the caudal aspect of the SMA tended to activate during the motor and sensory tasks. Right (contralateral) SMA activation was observed during the motor and sensory tasks, and left SMA activation during the word generation and memory tasks. CONCLUSION: Our results suggest that SMA is involved in a variety of functional tasks, including motor, sensory, word generation, and working memory. Some are tasks that are traditionally associated with this area (such as motor and sensory), and others are not (such as word generation and working memory). Qualitatively, the anterior and posterior portions of the SMA appeared to be engaged by different types of tasks.     

Radiofrequency thermal ablation in canine femur: evaluation of coagulation necrosis reproducibility and MRI-histopathologic correlation

OBJECTIVE: Our purposes were to determine whether a single application of radiofrequency energy to normal bone can create coagulation necrosis reproducibly and to assess the accuracy of MRI at revealing the extent of radiofrequency-induced thermal bone injury. MATERIALS AND METHODS: Using a 200-W generator and a 17-gauge cooled-tip electrode, a total of 11 radiofrequency ablations were performed under fluoroscopic guidance in the distal femurs of seven dogs. Radiofrequency was applied in standard monopolar mode at 100 W for 10 min. During radiofrequency ablation, the changes in impedance and currents were recorded. MRI, including unenhanced T1- and T2-weighted images and contrast-enhanced fat-suppressed T1-weighted images, was performed to evaluate ablation regions. Six dogs were killed on day 4 after MRI and one dog on day 7. RESULTS: In all animals, radiofrequency ablation created a well-defined coagulation necrosis and no significant complications were noted. The mean long-axis diameter and the mean short-axis diameter of the coagulation zones produced were 45.9 +/- 5.5 mm and 17.7 +/- 2.7 mm, respectively. At gross examination, thermal ablation regions appeared as a central, light-brown area with a dark-brown peripheral hemorrhagic zone, which was surrounded by a pale-yellow rim. On MRI, the ablated areas showed multilayered zones with signal intensities that differed from normal marrow on unenhanced images and a perfusion defect on contrast-enhanced T1-weighted images. The maximum difference between lesion sizes on MR images, established by measuring macroscopic coagulation necrosis, was 3 mm. The correlation between the diameter of coagulation necrosis and lesion size at MRI was strong, with correlation coefficients ranging from 0.89 for unenhanced T1-weighted images and 0.97 for unenhanced T2-weighted images to 0.98 for contrast-enhanced T1-weighted images (p < 0.05). CONCLUSION: Radiofrequency ablation created well-defined coagulation necrosis in a reproducible manner, and MRI accurately determined the extent of the radiofrequency-induced thermal bone injury.     

Differentiation of chronic focal pancreatitis from pancreatic carcinoma by in vivo proton magnetic resonance spectroscopy

OBJECTIVE: To determine the differences between the in vivo proton magnetic resonance spectroscopy (H-MRS) features of chronic focal pancreatitis and pancreatic carcinoma and to evaluate the possibility of discriminating chronic focal pancreatitis from pancreatic carcinoma by analysis of in vivo H-MR spectra. METHODS: The H-MR spectra from 36 human pancreases were evaluated in vivo. This series included 15 cases of chronic focal pancreatitis and 21 cases of pancreatic carcinoma. All cases were confirmed histopathologically after surgical resection. The ratios of the peak area (P) of all peaks at 1.6-4.1 ppm to lipid (0.9-1.6 ppm) (P [1.6-4.1 ppm]/P [0.9-1.6 ppm]) in the chronic focal pancreatitis and pancreatic carcinoma groups were evaluated, and the results were compared. The sensitivity and specificity of the analysis were also evaluated by in vivo H-MR spectra for discriminating between chronic focal pancreatitis and pancreatic carcinoma. RESULTS: In vivo H-MR spectra showed significantly less lipid in chronic focal pancreatitis than in pancreatic carcinoma. The ratio of P (1.6-4.1 ppm)/P (0.9-1.6 ppm) in chronic focal pancreatitis was significantly higher than that in pancreatic carcinoma (P < 0.05) because of a decreased peak area of lipids. The means +/- SDs of P (1.6-4.1 ppm)/P (0.9-1.6 ppm) in the chronic focal pancreatitis and pancreatic carcinoma groups were 2.78 +/- 1.67 and 0.51 +/- 0.49, respectively. Using a value of <2.5 as positive for pancreatic cancer, the sensitivity and the specificity for pancreatic cancer were 100% and 53.3%, respectively. CONCLUSION: Chronic focal pancreatitis and pancreatic carcinoma can be distinguished from each other by analysis of in vivo H-MR spectra, and in vivo H-MRS can be a useful method for making a differential diagnosis between chronic focal pancreatitis and pancreatic carcinoma.     

Bipolar radiofrequency ablation in ex vivo bovine liver with the open-perfused system versus the cooled-wet system

The aim of this study was to investigate the efficacy of bipolar radiofrequency ablation (RFA) with the open-perfused electrode and cooled-wet electrode. Bipolar RF was applied for 20 min to the ex vivo bovine liver using either the Berchtold system with two 16-gauge open-perfused electrodes (group A, n=15) or the Radionics system with two 15-gauge cooled-wet electrodes (group B, n=15). In both groups, two electrodes were placed 3 cm apart. The ablation zone was created by the RF energy delivered together with the infusion of 5% hypertonic saline (2 ml/min). The dimension of the ablation zone, its shape and the changes in the impedance and W s of two groups during the RFA were examined and documented. The vertical diameter (Dv) along the probe, the long-axis diameter (Dl) perpendicular to the Dv in the longitudinal plane and the short-axis diameter of the ablation zone (Ds) in the transverse plane through the midpoint between the tips of two probes were measured. The mean accumulated energy output in the Radionics system was higher than in the Berchtold system (159,887.0±36,423 W s vs. 87,555.1±86,787 W s). The difference was statistically significant (P<0.05). In group A, the impedance intermittently rose to above 700 during the RFA in all sessions, which led to a gradual decrease of the power output to lower than 30 W. In group B, on the other hand, the impedance did not change markedly. The mean Dv value of the coagulation necrosis in group B was significantly longer than in group A (5.0±0.4 cm vs. 4.3±0.6 cm, P<0.05). The mean Dl and Ds were 6.7±0.5 cm and 5.0±0.8 cm in group A, and 6.5±0.8 cm and 5.5±0.7 cm in group B, respectively (P>0.05). The data demonstrate that the cooled-wet electrode generates the more spherical ablation zone than the open-perfused electrode. With approximately doubled power output, the bipolar RFA with the cooled-wet electrodes induces a larger volume of tissue coagulation than with the open-perfused electrodes.     

Cyst fluid analysis for the differential diagnosis of pancreatic cysts

Pancreatic cystic neoplasms comprise a pathologically heterogeneous group with many shared clinical features. We assessed the reliability of cyst fluid analysis for the differential diagnosis of pancreatic cysts. Cyst fluid was obtained by fine-needle aspiration from 78 pancreatic cysts. The lesions studied consisted of 17 mucinous cystic tumors (MCTs), 13 serous cystadenomas (SCAs), 5 solid pseudopapillary tumors (SPTs), 8 intraductal papillary mucinous tumors (IPMTs), 6 ductal adenocarcinomas (ACAs) with cystic degeneration, and 29 pseudocysts (PCs). Epithelial cells were observed in 27 (81%) of 33 successful aspirates of cystic neoplasms. Cytologic diagnosis was possible in 5 (31%) out of 16 MCTs. Mucicarmine staining was positive in five out of nine MCTs, one out of one ACA, and one out of two IPMTs, but in none of the SCAs, SPTs, or PCs. Cyst fluid carcinoembryonic antigen (CEA) levels of more than 467 ng/mL had a 87% sensitivity and a 98% specificity for detecting MCTs, and amylase levels of more than 479 U/L had a 73% sensitivity and a 90% specificity for detecting PCs. In conclusion, cyst fluid analysis for cytology, mucin staining, CEA, and amylase levels are useful in the differential diagnosis of pancreatic cysts.     

Sampling design for an integrated socioeconomic and ecological survey by using satellite remote sensing and ordination

Environmental variability is an important risk factor in rural agricultural communities. Testing models requires empirical sampling that generates data that are representative in both economic and ecological domains. Detrended correspondence analysis of satellite remote sensing data were used to design an effective low-cost sampling protocol for a field study to create an integrated socioeconomic and ecological database when no prior information on ecology of the survey area existed. We stratified the sample for the selection of tambons from various preselected provinces in Thailand based on factor analysis of spectral land-cover classes derived from satellite data. We conducted the survey for the sampled villages in the chosen tambons. The resulting data capture interesting variations in soil productivity and in the timing of good and bad years, which a purely random sample would likely have missed. Thus, this database will allow tests of hypotheses concerning the effect of credit on productivity, the sharing of idiosyncratic risks, and the economic influence of environmental variability.     

Crystal structure of YjeQ from Thermotoga maritima contains a circularly permuted GTPase domain

We have determined the crystal structure of the GDP complex of the YjeQ protein from Thermotoga maritima (TmYjeQ), a member of the YjeQ GTPase subfamaily. TmYjeQ, a homologue of Escherichia coli YjeQ, which is known to bind to the ribosome, is composed of three domains: an N-terminal oligonucleotide/oligosaccharide-binding fold domain, a central GTPase domain, and a C-terminal zinc-finger domain. The crystal structure of TmYjeQ reveals two interesting domains: a circularly permutated GTPase domain and an unusual zinc-finger domain. The binding mode of GDP in the GTPase domain of TmYjeQ is similar to those of GDP or GTP analogs in ras proteins, a prototype GTPase. The N-terminal oligonucleotide/oligosaccharide-binding fold domain, together with the GTPase domain, forms the extended RNA-binding site. The C-terminal domain has an unusual zinc-finger motif composed of Cys-250, Cys-255, Cys-263, and His-257, with a remote structural similarity to a portion of a DNA-repair protein, rad51 fragment. The overall structural features of TmYjeQ make it a good candidate for an RNA-binding protein, which is consistent with the biochemical data of the YjeQ subfamily in binding to the ribosome.