Wolfgang Schima

PERCUTANEOUS RADIOFREQUENCY TISSUE ABLATION : DOES PERFUSION-MEDIATED TISSUE COOLING LIMIT COAGULATION NECROSIS ?

PURPOSE To determine, by decreasing hepatic perfusion during radiofrequency (RF) ablation, whether perfusion-mediated tissue cooling can explain the reduced coagulation observed in in vivo studies compared to that seen with RF application in ex vivo tissue. MATERIALS AND METHODS RF was applied in vivo with use of cooled-tip electrodes to normal porcine liver without (n = 8) and with balloon occlusion of the portal vein (n = 8), celiac artery (n = 3), or hepatic artery (n = 2), and to ex vivo calf liver (n = 10). In vivo trials of vasopressin (0.3-0.6 U/min) infusion during RF application with (n = 10) and without (n = 2) arterial balloon occlusion were also performed. Intraoperative RF was subsequently performed in seven patients with hepatic colorectal metastases with and without portal inflow occlusion. Remote thermometry was performed in four patients. RESULTS RF application (12 minutes) during portal venous occlusion produced larger areas of coagulation necrosis than RF with unaltered blood flow (2.9 cm +/- 0.1 vs 2.4 cm +/- 0.2 diameter; P < .01). With celiac and hepatic artery occlusion, coagulation diameter measured 2.7 cm +/- 0.2 and 2.5 cm +/- 0.1, respectively. Infusion of vasopressin without vascular occlusion reduced coagulation diameter to 1.1 cm. However, different methods of hepatic or celiac arterial balloon occlusion with simultaneous vasopressin infusion produced a mean 3.4 cm +/- 0.2 of necrosis. Coagulation in ex vivo liver was 2.9 cm +/- 0.1 in diameter. Clinical studies demonstrated greater coagulation diameter for metastases treated during portal inflow occlusion (4.0 cm +/- 1.3) than for tumors treated with normal blood flow (2.5 cm +/- 0.8; P < .05). Thermometry documented a 10 degrees C increase compared to baseline at 10 mm and 20 mm from the electrode after 5 minutes of portal inflow occlusion during constant RF application. CONCLUSIONS Perfusion-mediated tissue cooling reduces coagulation necrosis achievable with RF ablation. Reduction of blood flow during RF application increases coagulation in both an animal model and human liver metastases.

Usefulness of magnetic resonance imaging of cardiac and paracardiac masses

In this study, magnetic resonance imaging was compared with histology to evaluate the usefulness of magnetic resonance imaging to distinguish malignant from benign cardiac and paracardiac masses in 55 patients. Tumor location, tissue composition, and pericardial or pleural effusion all were identified as key predictors of lesion type. Observers were accurate in the prediction of lesion type (area under curve 0.88 and 0.92), and there was good interobserver variability (Cohens kappa = 0.64).

Detection of focal hepatic lesions: comparison of unenhanced and SHU 555 A-enhanced MR imaging versus biphasic helical CTAP.

The purpose of this study was to compare the diagnostic sensitivity of unenhanced magnetic resonance (MR) imaging, and MR imaging with a new superparamagnetic iron oxide (SPIO)‐enhanced contrast agent (SHU 555 A) with biphasic helical computed tomography during arterial portography (CTAP) in patients with focal liver lesions. Eighteen patients with a total of 91 (78 malignant, 13 benign) proven liver lesions underwent unenhanced short tau inversion recovery (STIR), T2‐weighted (T2‐w) TSE, and SHU 555 A‐enhanced T2‐w turbo spin‐echo (TSE) MR imaging and biphasic helical CTAP. The standard of reference was histopathologic analysis of resected specimens in 59 lesions, intraoperative ultrasound with biopsy in 20 lesions, and CT‐guided biopsy and follow‐up in 12 lesions. Diagnostic performance of the imaging modalities was compared quantitatively and qualitatively by assessing lesion involvement in liver segments. There were 68 lesions detected on unenhanced T2‐w TSE, which resulted in a sensitivity of 75%. With the STIR sequence, 76 lesions were detected, for a sensitivity of 84%, and with SHU 555 A‐enhanced MRI, 84 lesions were detected, for a sensitivity of 92%. CTAP detected 88 lesions, for a sensitivity of 97%. The accuracy for unenhanced T2‐w TSE was 98%, for STIR 99%, for enhanced‐MRI 100%, and for CTAP 95%. The specificity was 100% for SHU 555 A‐enhanced MRI and 95% for CTAP. SHU 555 A‐enhanced MRI was superior to nonenhanced MRI (P < 0.05) and equivalent to CTAP in terms of sensitivity. Due to the absence of false‐positive results on SHU 555 A‐enhanced MRI, the specificity and accuracy of enhanced MRI were higher than those of CTAP, but the difference was not statistically significant (P = 0.134). J. Magn. Reson. Imaging 2000;11:665–672.

Evaluation of perianal sepsis: Comparison of anal endosonography and magnetic resonance imaging

The purpose of this study was to compare prospectively the diagnostic yield of anal endosonography (AES) and magnetic resonance imaging (MRI) in the assessment of perianal fistulae and abscesses. There were 39 patients (14 men, 25 women; mean age, 40 years) who underwent AES, performed with a 10‐MHz rotating endoanal probe and MRI at 1.0 T (axial and coronal T2‐weighted turbo spin‐echo (TSE) and turbo‐STIR sequences). Fistulae were classified as subcutaneous, intersphincteric, transsphincteric, high (i.e., high extrasphincteric or suprasphincteric), rectovaginal, and horseshoe and were compared with the surgical findings in all patients. Overall, 58 fistulae (subcutaneous, N = 7; intersphincteric, N = 9; transsphincteric, N = 16; high, N = 17; rectovaginal, N = 5; and horseshoe, N = 4) were detected at surgery. MRI showed a sensitivity of 84% and AES of 60% (P < .05). False‐positive diagnoses were made in 6 patients (15%) with MRI and in 15 patients (26%) with AES, for a specificity of 68% and 21%, respectively (P < .05). Our findings show that MRI is superior to AES in the assessment of fistula‐in‐ano before major surgery. AES should be used only for orientation before minor procedures, such as incision or drainage of subcutaneous fistulae. J. Magn. Reson. Imaging 2001;14:254–260.

Diagnostic Value of CT Enteroclysis Compared with Conventional Enteroclysis in Patients with Crohn's Disease

OBJECTIVE The objective of our study was to assess the diagnostic value of CT enteroclysis compared with conventional enteroclysis in patients with Crohns disease. SUBJECTS AND METHODS Fifty consecutive patients (26 women, 24 men; mean age, 36.3 years; age range, 18-52 years) with histologically proven Crohns disease underwent CT enteroclysis and conventional enteroclysis (median time interval, 21.7 days) during a symptomatic stage of their disease. Both techniques were compared with regard to diagnostic yield in assessing the presence and extent of disease. Imaging findings were compared with surgery, follow-up examinations, or both. RESULTS CT enteroclysis and conventional enteroclysis were successfully performed in all 50 patients. Crohns disease-associated radiographic changes were found in 44 patients (88%) using CT enteroclysis and in 42 patients (84%) using conventional enteroclysis. Significantly more Crohns disease-associated abnormalities were diagnosed with CT enteroclysis than with enteroclysis (p < 0.01). Minimal inflammatory changes of the mucosa were diagnosed in 44 patients (88%) using CT enteroclysis and in 42 patients (84%) using enteroclysis. Both imaging methods depicted stenotic bowel segments in 34 patients (68%), and prestenotic dilatation was diagnosed in 20 patients (40%) with CT enteroclysis and in 15 (30%) with enteroclysis. Fistulas were found in 18 patients (36%) with CT enteroclysis and in eight (16%) with enteroclysis (p < 0.01). Skip lesions could be seen in 17 (34%) and three patients (6%), respectively (p < 0.01). Conglomeration of bowel loops tumors was diagnosed with CT enteroclysis in 13 patients (26%) and in three patients (6%) using conventional enteroclysis (p < 0.01). Only CT enteroclysis depicted abscesses in eight patients (16%) (p < 0.01). CONCLUSION CT enteroclysis proved to be significantly superior to conventional enteroclysis in depicting Crohns disease-associated intra- and extramural abnormalities. CT enteroclysis is the imaging method of choice and should replace enteroclysis in patients with Crohns disease.

Findings at helical CT-enteroclysis in symptomatic patients with crohn disease: correlation with endoscopic and surgical findings.

Purpose The purpose of our study was to assess the diagnostic potential of helical CT–enteroclysis (HCTE) and to correlate our findings to endoscopic and surgical results. Methods Twenty-eight consecutive patients suffering from histologic proven Crohn disease underwent HCTE and endoscopy within 4 weeks. HCTE findings were read by two observers in consensus and compared with endoscopic and surgical results. Results Morphological signs of an acute or recurrent bowel inflammation were found in 25 of 28 (89%) patients. HCTE demonstrated accurately all mural and extramural changes of the inflamed bowel walls. Moreover, in 18 of 25 (72%) patients, HCTE depicted additional pathologic changes such as fistulas, abscesses, and skip lesions, all of which could not be visualized by endoscopy. Conclusion HCTE is an accurate technique to detect mural and extramural abnormalities in patients with Crohn disease. HCTE should be considered as a complementary imaging method to endoscopy, and should be the first imaging method especially when Crohn-associated complications are suspected.

Liver metastases of colorectal cancer: US, CT or MR?

In contrast to other extrahepatic malignancies many colorectal cancers can be cured even when there is metastatic spread to the liver. The diagnosis of liver metastases relies totally on imaging to decide which patients may be surgical candidates. The diagnostic value of ultrasound with contrast agents, multidetector CT and MR imaging with non-specific gadolinium chelates and liver-specific contrast agent is discussed. Nowadays MDCT is the mainstay of staging and follow-up of these patients, because it provides good coverage of the liver and the complete abdomen and the chest in one session. MR imaging has been shown to be superior to helical CT in the preoperative assessment of colorectal liver metastases. Large studies are needed to define the role of MDCT vs. MRI staging in patients referred for resection of liver metastases.

Biliary wallstent endoprosthesis in malignant hilar obstruction: Long-term results with regard to the type of obstruction

AIM To evaluate the clinical efficacy of percutaneously placed biliary Wallstents in the management of malignant hilar obstruction with regard to the obstruction type. PATIENTS AND METHODS Sixty-six Wallstents were inserted in 41 patients with inoperable hilar obstruction: 13 patients had a type I obstruction according to Bismuth-classification, 18 a type II, eight a type III, and two a type IV obstruction, respectively. Clinical follow-up data were obtained from all the patients and the referring physicians. RESULTS Stent placement was technically successfully in all patients. The procedure-related death rate was 2% (one patient), but the overall 30-day mortality rate was 39%, mostly due to advanced malignant disease, cardiac failure or pneumonia. Stent occlusion was found in 11 patients (27%) after 87 days (mean; range, 8-190 days). After stent placement, the mean stent patency was 96 days and the mean survival was 131 days with no significant difference between patients with obstruction type I, II and III. Multivariate analysis revealed that patients with obstruction due to gallbladder carcinoma had a significantly shorter survival than patients with cholangio-carcinoma or hilar obstruction due to metastases. CONCLUSION Overall, the insertion of Wallstent endoprostheses offers moderate results for palliation of hilar biliary obstruction regardless of the type of obstruction. In patients with cholangiocarcinoma, long-term results are good even for complicated strictures (type III). In patients with hilar obstruction due to gallbladder carcinoma the outcome is generally poor, regardless of the type of obstruction.

Preoperative detection of colorectal liver metastases in fatty liver: MDCT or MRI?

OBJECTIVE To compare the diagnostic value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative detection of colorectal liver metastases in diffuse fatty infiltration of the liver, associated with neoadjuvant chemotherapy. MATERIALS AND METHODS Twenty preoperative tri-phasic MDCT (4-64-row, Siemens) and dynamic contrast-enhanced MRI (1.5T or 3.0T, Siemens) examinations of patients with colorectal cancer and liver metastases in diffuse steatosis were retrospectively evaluated. All patients underwent surgical resection for liver metastases (time interval 1-60 days). The amount of fatty infiltration of the liver was determined histopathologically by semi-quantitative percent-wise estimation and ranged from 25 to 75%. RESULTS Overall, 51 metastases were found by histopathology of the resected liver segments/lobes. The size of the metastases ranged from 0.4 to 13 cm, with 18 (35%) being up to 1cm in diameter. In the overall rating, MDCT detected 33/51 lesions (65%), and MRI 45/51 (88%). For lesions up to 1cm, MDCT detected only 2/18 (11%) and MRI 12/18 (66%). One false positive lesion was detected by MDCT. Statistical analysis showed that MRI is markedly superior to MDCT, with a statistically significant difference (p<.001), particularly for the detection of small lesions (≤ 1 cm; p<.004). There was no significant difference between the two modalities in the detection of lesions>1cm. CONCLUSION For the detection of colorectal liver metastases after neoadjuvant chemotherapy and consecutive diffuse fatty infiltration of the liver, MRI is superior to MDCT, especially for the detection of small lesions.

Aortic mural thrombi in patients with inflammatory bowel disease. Report of two cases and review of the literature

Thromboembolic events are a known complication in inflammatory bowel disease (IBD). We report on 2 young women with IBD and aortic mural thrombi as a source of arterioarterial embolization to the lower limbs resulting in significant morbidity. The first case was a 36-year-old woman with severe ulcerative colitis who presented with signs of microembolism into two toes of her right foot. A thrombus in the otherwise normal infrarenal aorta with occlusion of the inferior mesenteric artery was revealed by computed tomography (CT) and intrarterial angiography. The digital ischemia resolved without sequelae. The second case was a 41-year-old woman with Crohns disease complicated by fistulas. She developed acute ischemia of her right leg. Arteriography and CT revealed infrapopliteal embolic occlusions and a thrombus in the distal otherwise normal abdominal aorta and the left iliac artery. A primarily successful thrombectomy had to be repeated 5 times because of reocclusion. Eventually the leg was exarticulated at the knee. In both patients no further thromboembolic event occurred during follow-up of 4 1/2 years and 5 1/2 years, respectively, and aortic thrombi had resolved at follow-up CT scans. Extensive work up for hypercoagulability was negative in both patients. We consider IBD as the most likely trigger for arterioarterial embolization in the absence of thrombophilia in both patients. Finally we give an overview of the literature of similar cases with aortic mural thrombi in IBD patients.