Extracolonic findings at CT colonography.

This review focuses on the detection of extracolonic findings at CT colonography (CTC). Since its introduction, it has been regarded as a promising alternative to conventional colonoscopy for the detection of colorectal polyps and cancers. Unlike conventional colonoscopy and barium enema, CTC allows evaluation not only of the colon but also visualization of the lung bases, the abdomen, and the pelvis. CTC is performed with thin sections (1-5 mm) and small intervals (0.5-2 mm), enabling superb image reconstruction. The ability to evaluate the extracolonic structures can present a clinical dilemma. On the one hand, CTC may incidentally demonstrate asymptomatic malignant diseases or other clinically important conditions, thus possibly reducing morbidity or mortality. On the other hand, CTC may reveal numerous findings of no clinical relevance; this could result in costly additional diagnostic examinations with an increase in morbidity and overall negative impact on patients' health. In this article, extracolonic findings at CTC will be reviewed and the potential benefits and disadvantages will be presented.

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.

Role of virtual computed tomographic colonography in patients with colorectal cancers and obstructing colorectal lesions.

PURPOSE: The aim of this study was to assess the ability of computed tomographic colonography to diagnose colorectal masses, stage colorectal cancers, image the proximal colon in obstructing colorectal lesions, and evaluate the anastomoses in patients with previous colorectal surgery. METHODS: We prospectively performed computed tomographic colonography examinations in 34 patients (20 males; mean age, 64.2; range, 19-91 years): 20 patients had colorectal masses (defined at endoscopy as intraluminal masses 2 cm or larger), 7 patients had benign obstructing colorectal strictures, and 7 patients had a prior colorectal resection. Final tumor staging was available in all 16 patients who had colorectal cancers and 15 patients were referred after incomplete colonoscopy. The ability of computed tomographic colonography to stage colorectal cancers, identify synchronous lesions in patients with colorectal masses, and image the proximal colon in patients with obstructing colorectal lesions was assessed. RESULTS: Computed tomographic colonography identified all colorectal masses, but overcalled two masses in patients who were either poorly distended or poorly prepared. Computed tomographic colonography correctly staged 13 of 16 colorectal cancers (81 percent) and detected 16 of 17 (93 percent) synchronous polyps. Computed tomographic colonography over-staged two Dukes Stage A cancers and understaged one Dukes Stage C cancer. A total of 97 percent (87/90) of all colonic segments were adequately visualized at computed tomographic colonography in patients with obstructing colorectal lesions compared with 60 percent (26/42) of segments at barium enema (P < 0.01). Colonic anastomoses were visualized in all nine patients, but in one patient, computed tomographic colonography could not distinguish between local tumor recurrence and surgical changes. CONCLUSION: Computed tomographic colonography can accurately identify all colorectal masses but may overcall stool as masses in poorly distended or poorly prepared colons. Computed tomographic colonography has an overall staging accuracy of 81 percent for colorectal cancer and is superior to barium enema in visualizing colonic segments proximal to obstructing colorectal lesions.

Endoluminal CT colonography after an incomplete endoscopic colonoscopy.

OBJECTIVE: We evaluated the clinical usefulness of endoluminal CT colonography after an incomplete colonoscopy. SUBJECTS AND METHODS: We prospectively studied 40 patients in whom the cecum could not be reached endoscopically despite adequate bowel preparation. Endoluminal CT colonography (120 kVp, 120 mA, 3-mm collimation, pitch of 2, 1.5-mm interval reconstruction) was performed within 2 hr of incomplete colonoscopy. Two-dimensional multiplanar reformatted images and three-dimensional endoluminal images were analyzed. Twenty-six patients (65%) underwent barium enema immediately after endoluminal CT colonography. We analyzed colonic distention; duration of endoluminal CT colonography; patient tolerance; number of colonic segments seen at colonoscopy, endoluminal CT colonography, and barium enema; and reasons for incomplete colonoscopy as well as colonic and extracolonic findings. RESULTS: Duration of endoluminal CT colonography was 14.2 +/- 4.6 min (mean +/- SD). Endoluminal CT colonography was better tolerated than colonoscopy or barium enema (p < .001). Probable causes for incomplete colonoscopy were identified at endoluminal CT colonography in 74% of 40 patients. Baseline colonic distention in the region of the transverse and right colon was considered adequate before additional air insufflation; however, the addition of air significantly enhanced colonic distention throughout the entire colon (p < .001). Endoluminal CT colonography adequately revealed 96% of all colonic segments; in comparison, barium enema adequately revealed 91% of all segments (p < .05). CONCLUSION: In patients with incomplete colonoscopy, endoluminal CT colonography successfully showed the previously unrevealed colon in more than 90% of patients. Endoluminal CT colonography is a rapid, well-tolerated technique that provides clinically useful colonic and extracolonic information and should be considered for all patients who undergo incomplete colonoscopy.

Chemoembolization for hepatocellular carcinoma: epinephrine followed by a doxorubicin-ethiodized oil emulsion and gelatin sponge powder.

PURPOSE: This study evaluates chemoembolization (CE) of the liver with minimal vasoconstriction followed by selective intraarterial delivery of an emulsion of iopamidol, doxorubicin, and ethiodized oil and temporary occlusion of hepatic artery with gelatin sponge powder in patients with hepatocellular carcinoma. PATIENTS AND METHODS: Since 1988, 30 patients with nonresectable hepatocellular carcinoma underwent CE with the above protocol. Intraarterial epinephrine (0.5-1 microgram diluted in 10 mL of saline) was rapidly injected directly into the proper hepatic artery or selectively into the right or left hepatic arteries and was followed by 40-60 mg of doxorubicin dissolved in 10 mL of iopamidol and emulsified in 20 mL of ethiodized oil. The chemoembolic mixture was injected at the rate of arterial flow. Liver function and clotting parameters were monitored three times a day until there was a downward trend toward preembolic levels. Computed tomography (CT) was performed immediately after embolization and at 1-3-month intervals. Embolization was repeated when CT demonstrated recurrent or progressive disease. RESULTS: Disease recurred or progressed in 11 patients at 2-17 months after embolization. CE was repeated in four patients; one individual underwent three embolizations. Re-embolization was performed up to 14 months after initial embolization (median, 10 months). Five patients (16.7%) died within 1 month of embolization. Ten patients died at 3-33 months after CE. Two of these patients died of cirrhosis at 6 and 14 months, without evidence of recurrent tumor. Fifteen patients remain alive 5-28 months after CE. Kaplan-Meier estimation of probability of survival curves demonstrates a median survival of 14 months. Sixty-one percent of patients were alive at 1 year and 36% at 2 years after the procedure. CONCLUSION: CE with use of the above technique is effective for palliating inoperable hepatocellular carcinoma. It causes a significant prolongation of survival over the expected 18-24 weeks in untreated patients; this may occur because high doses of chemotherapeutic agents are delivered and come in contact with the tumor for a longer period, followed by ischemia brought about by temporary arterial occlusion.

In vivo and in vitro analysis of the effectiveness of doxorubicin combined with temporary arterial occlusion in liver tumors.

PURPOSE: The authors evaluated the effects of daunomycin (daunorubicin)--an analogue of doxorubicin--ethiodized oil, and arterial occlusion on an in vitro hepatoma analogue and on in vivo rat liver tumors. MATERIALS AND METHODS: A human Sk hepatoma cell monolayer sandwich system was used to determine uptake of 3H-daunomycin under normoxic/hypoxic conditions with use of autoradiography. Fluorescence microscopy was used to evaluate the biodistribution of doxorubicin in cell cultures (human Sk hepatoma and colon carcinoma). Microvascular flow adjacent to and within liver tumors and the intrahepatic effects of doxorubicin and ethiodized oil were studied with in vivo video microscopy on exteriorized rat livers containing peripheral hepatomas. RESULTS: Increased uptake of 3H-daunomycin by hepatoma cells occurred under hypoxic conditions. Intrahepatic arterial administration of ethiodized oil caused temporary occlusion of peripheral sinusoids following passage through arterioportal anastomoses. Tumors received portal venous and neovascular blood supply and ethiodized oil occluded but did not enter the narrow neovasculature perfusing the tumors. CONCLUSION: Hypoxia increases uptake of 3H-daunomycin by human Sk hepatoma and colon carcinoma cell cultures. Selective hepatic arterial occlusion (and perhaps the resultant hypoxia) may facilitate increased uptake of doxorubicin analogues into liver tumors. Hepatomas receive both arterial and portal venous blood supply, and ethiodized oil reaches the tumor via arterioportal anastomoses that perfuse the tumor periphery.

23Na- and 31P-NMR studies of perfused mouse liver during nitrogen hypoxia.

The effects of nitrogen hypoxia on isolated perfused mouse livers from fed mice were studied at 37 degrees C using 23Na and 31P nuclear magnetic resonance (NMR) spectroscopy. The paramagnetic shift reagent, dysprosium-triethylenetetraminehexaacetic acid, was used to distinguish intracellular from extracellular sodium. The area of the intracellular sodium resonance remained relatively constant over the first 30 min of hypoxia and then increased by a factor of approximately 2 relative to controls over the next 30 min. High-energy phosphate metabolites were measured using 31P-NMR. The beta-ATP resonance decreased to zero, and the intracellular pH decreased from 7.3 to 6.9 during 60 min of hypoxia. Liver enzyme activity in the effluent exiting the liver increased in direct proportion to the length of hypoxia up to 56 min. The sodium, ATP, and enzyme changes during hypoxia were correlated with histological and electron-microscopic findings. The morphology of liver specimens exposed to 30 min of hypoxia was close to normal, whereas extensive centrilobular and midlobular necrosis was seen in specimens subjected to 60 and 90 min of hypoxia. The effect of 30 min of reoxygenation after 15, 30, 45, 60, and 90 min of hypoxia was also studied. The level of beta-ATP recovery depended on the duration of hypoxia. For 60 min of hypoxia followed by reoxygenation, beta-ATP recovered to only 20% of control values. The morphology of hypoxic livers after 30 min of reoxygenation was similar to livers subjected to hypoxia alone.