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Biomedical subjects

G D Dodd

Publications and source records attributed to G D Dodd.

At least 19 recordsLinked to original sources
PubMed2001

Minimally invasive techniques for the treatment of liver tumors.

Recently, several minimally invasive, image-guided therapies have been developed for the local treatment of hepatocellular carcinoma (HCC) and hepatic metastases in patients who are considered poor candidates for surgical resection. Radio-frequency ablation, microwave ablation, and laser ablation all destroy tumor by creating a hyperthermic injury. Cryoablation and ethanol ablation achieve cellular death through freezing and direct toxicity, respectively. Chemoembolization is unique in that the entire liver can be treated over time with a combination of cytotoxic drugs and embolic agents, potentially reducing the rate of recurrence from radiologically occult tumor. Outcomes for minimally invasive therapy have approached the success rate of surgical resection in some series with considerably fewer complications. However, a paucity of randomized trials and variability in reporting limit assessment of the relative role of these techniques in clinical practice. With a few exceptions, the indications, contraindications, and complications associated with the different techniques are similar, and success with HCC has exceeded that for metastatic disease independent of technique.

Carcinoma, Hepatocellular↗
PubMed2001

Essential techniques for successful radio-frequency thermal ablation of malignant hepatic tumors.

Radio-frequency thermal ablation is one of the most promising minimally invasive techniques for the treatment of nonresectable hepatic tumors. Essential technical tips to successful radio-frequency ablation therapy were collected from five international experts. They were organized into five categories: understanding the mechanisms and principles of radio-frequency ablation, modulation of tissue physiologic characteristics to increase tumor destruction, strategies of overlapping ablations, strategies to improve ablation according to tumor location, and imaging strategies after ablation to ensure adequate therapy. Established factors for optimal ablation, as well as emerging technical tips, are addressed with illustrations in each section. These essential tips will be very helpful for physicians performing radio-frequency ablation of hepatic tumors.

Catheter Ablation↗
PubMed2001

Treatment of acute cholecystitis in non-critically ill patients at high surgical risk: comparison of clinical outcomes after gallbladder aspiration and after percutaneous cholecystostomy.

OBJECTIVE: This study was performed to compare the clinical outcome after gallbladder aspiration with that after percutaneous cholecystostomy in non-critically ill patients with acute cholecystitis who were at high risk from surgery. MATERIALS AND METHODS: Medical records of 53 consecutive non-critically ill, high-surgical-risk patients admitted with acute cholecystitis between July 1995 and July 1999 were reviewed. Thirty-one had gallbladder aspiration and 22 had percutaneous cholecystostomy. The primary outcome measure of clinical response within 72 hr and the secondary outcome measures of overall positive response rate, complication rate, time to resolution, and rate of recurrence of acute cholecystitis were compared between the two groups. RESULTS: Gallbladder aspiration and percutaneous cholecystostomy were technically successful in 30 (97%) and 21 (97%) patients, respectively; of these, 23 (77%) and 19 (90%) patients responded clinically within 72 hr (p > 0.2). Complications occurred in three patients (12%) after percutaneous cholecystostomy and in none after gallbladder aspiration (p < 0.05). No significant difference was noted in the other secondary outcome measures of the two groups. CONCLUSION: We found no significant difference in the clinical outcomes of gallbladder aspiration and percutaneous cholecystostomy in the treatment of acute cholecystitis in high-surgical-risk patients who are not critically ill. However, we found gallbladder aspiration to be significantly safer. Therefore, gallbladder aspiration should be the procedure of choice in high-risk patients with acute cholecystitis who are not critically ill, and percutaneous cholecystectomy should be reserved as a salvage procedure if gallbladder aspiration is technically or clinically unsuccessful.

Acute Disease↗
PubMed2001

Tumor recurrence after radiofrequency thermal ablation of hepatic tumors: spectrum of findings on dual-phase contrast-enhanced CT.

OBJECTIVE: We conducted this study to determine the spectrum of CT findings of tumor recurrence after radiofrequency ablation of primary and secondary malignant hepatic tumors. MATERIALS AND METHODS: Twenty-five patients, 10 with hepatocellular carcinoma (HCC) and 15 patients with metastases who developed tumor recurrence after radiofrequency ablation of hepatic neoplasms, formed the study population. Three observers reviewed the CT scans of these patients and evaluated the location (local intrahepatic, remote intrahepatic, or extrahepatic) of all recurrent lesions and the morphology and enhancement characteristics of local intrahepatic recurrences. RESULTS: Local intrahepatic recurrences were seen in nine patients (90%) and 11 patients (73%); remote intrahepatic recurrences, in five patients (50%) and seven patients (45%); and extrahepatic recurrences, in zero and six patients (40%) with recurrent HCC and recurrent metastases, respectively. Of the 12 nodules of local intrahepatic recurrences in HCC and the 24 in metastases, the patterns of local intrahepatic recurrences were of nodular, halo, and gross enlargement types in eight (67%) and nine (38%), four (33%) and six (38%), and zero and nine (37%) nodules in HCC and hepatic metastases, respectively. The number of local intrahepatic recurrent lesions enhancing in the arterial phase was significantly greater in HCC. CONCLUSION: Tumor recurrences occurred at intra- and extrahepatic sites after radiofrequency ablation of hepatic neoplasms. The local intrahepatic recurrences appeared in three patterns: nodular, halo, or gross enlargement. The sites of recurrence and the morphologic patterns of local intrahepatic tumor recurrence differed between primary and secondary hepatic neoplasms.

Carcinoma, Hepatocellular↗
PubMed2001

Radiofrequency thermal ablation: computer analysis of the size of the thermal injury created by overlapping ablations.

OBJECTIVE: The purpose of this study was to perform a computer analysis of the size of the thermal injury created by overlapping multiple thermal ablation spheres. MATERIALS AND METHODS: A computer-assisted design system was used to create three-dimensional models of a spherical tumor, a spherical tissue volume consisting of the tumor plus a 1-cm tumor-free margin, and individual spherical ablations. These volumes were superimposed in real-time three-dimensional space in different geometric relationships. The effect of the size and geometric configuration of the ablation spheres was analyzed with regard to the ability to ablate the required volume of tissue (tumor plus margin) without leaving untreated areas or interstices. RESULTS: The single-ablation model showed that if a 360-degree 1-cm tumor-free margin is included around the tumor targeted for ablation, radiofrequency ablation devices producing 3-, 4-, and 5-cm ablation spheres can be used to treat 1-, 2-, and 3-cm tumors, respectively. The six-sphere model, in which six ablation spheres are placed in orthogonal planes around the tumor, showed that the largest tumor that may be treated with a 3-cm ablation device is 1.75 cm, whereas 4- and 5-cm ablation spheres can be used to treat tumors measuring 3 and 4.25 cm, respectively. The 14- sphere model showed that addition of eight more spheres to the six-sphere model increased the treatable tumor size to 3, 4.6, or 6.3 cm, depending on the diameter of the ablation sphere used. For treating larger tumors, we found a cylindrical model to be less efficient but easier to control. CONCLUSION: Our computer analysis showed that the size of the composite thermal injury created by overlapping multiple thermal ablation spheres is surprisingly small relative to the number of ablations performed. These results emphasize the need for a methodic tumor ablation strategy.

Computer Simulation↗
PubMed2000

Helical CT cholangiography with oral cholecystographic contrast material.

Twenty asymptomatic volunteers underwent helical computed tomographic (CT) cholangiography 10-12 hours after ingesting iopanoic acid. Three observers assessed the images for the extent of bile duct visualization and image quality. The common bile duct and common hepatic duct were adequately visualized in 19 (95%) subjects. Helical CT cholangiography with oral cholecystographic contrast material is feasible and deserves further clinical studies.

Administration, Oral↗
PubMed2000

Gastrointestinal wall thickening in patients with cirrhosis: frequency and patterns at contrast-enhanced CT.

PURPOSE: To determine the frequency and patterns of gastrointestinal wall thickening at contrast material-enhanced computed tomography (CT) in patients with cirrhosis. MATERIALS AND METHODS: Three radiologists retrospectively assessed the contrast-enhanced abdominal CT scans of 77 patients with cirrhosis and 100 patients without cirrhosis for gastrointestinal wall thickening from the stomach through the descending colon. The frequencies of wall thickening were determined in the cirrhosis and in the control groups and were compared by using the Fisher exact test. The segmental distribution, symmetry, and enhancement pattern were evaluated in all patients with cirrhosis and gastrointestinal wall thickening. RESULTS: Gastrointestinal wall thickening was seen in 49 (64%) patients with cirrhosis and in seven (7%) control subjects (P <.005). The jejunum and ascending colon were the most common sites of gastrointestinal wall thickening; each was involved in 32 (42%; 95% CI: 30%, 53%) patients. The scans of 30 (61%; 95% CI: 47%, 75%) patients with gastrointestinal wall thickening showed multisegmental distribution. Gastrointestinal wall thickening was concentric and homogeneous in all patients with cirrhosis. CONCLUSION: Gastrointestinal wall thickening is common on contrast-enhanced abdominal CT scans in patients with cirrhosis. It frequently involves multiple segments. The jejunum and ascending colon are the most common sites of involvement.

Adult↗
PubMed2000

Transjugular intrahepatic portosystemic shunt: accuracy of helical CT angiography in the detection of shunt abnormalities.

PURPOSE: To determine the sensitivity, specificity, and accuracy of helical computed tomographic (CT) angiography in the detection of transjugular intrahepatic portosystemic shunt (TIPS) stenoses or occlusions. MATERIALS AND METHODS: Thirty-seven patients underwent 50 helical CT angiographic examinations and, within 2 weeks of each examination, portography with measurement of the portosystemic pressure gradient. Helical CT angiograms were independently interpreted by three radiologists who were blinded to the results of portography. Results of helical CT angiography and portography were compared. Sensitivity and specificity of helical CT angiography were separately calculated for the demonstration of morphologic abnormalities and the determination of their hemodynamic significance. RESULTS: Of the 50 portograms, 31 (62%) demonstrated morphologic TIPS abnormalities, 24 (77%) with and seven (23%) without elevated portosystemic pressure gradients. Helical CT angiograms correctly demonstrated 30 (97%) of the 31 morphologic abnormalities and allowed correct diagnosis of 22 (92%) of the 24 hemodynamically significant abnormalities. Nineteen (38%) portograms were normal; helical CT angiograms correctly demonstrated the absence of abnormality in 17 (90%) of these cases. Sensitivity and specificity of helical CT angiography for all morphologic abnormalities were 97% and 89%, respectively, and, for hemodynamically significant abnormalities, 92% and 77%. CONCLUSION: Helical CT angiography holds promise as a screening modality for the detection of TIPS stenoses or occlusions.

Adult↗
PubMed1999

Radiofrequency thermal ablation of liver tumors.

Chemotherapy and radiation therapy are ineffective against primary and secondary malignant hepatic tumors. Surgical resection has been considered the only potentially curative option, but few patients with hepatic tumors are candidates for surgery. Recent results suggest that radiofrequency thermal ablation may be an effective, minimally invasive technique for treating malignant hepatic tumors. Sonography is the primary technique for guiding percutaneous ablative procedures. We review the current research and clinical experience with radiofrequency thermal ablation for treating malignant hepatic tumors.

Catheter Ablation↗
PubMed1999

Helical CT angiography of transjugular intrahepatic portosystemic shunts.

Shunt dysfunction due to draining hepatic vein and/or stent stenosis is a common long-term complication of transjugular intrahepatic portosystemic shunts (TIPS). Currently, Doppler sonography is the preferred modality for routine screening of TIPS for the detection of these complications. However, this method is time-consuming, highly operator-dependent, and difficult to perform because of the anatomic attributes of the cirrhotic liver. The use of helical CT angiography (HCTA) for imaging TIPS has been recently described. HCTA of TIPS is performed after a rapid i.v. injection of a bolus of low osmolality contrast medium, followed by helical data acquisition of the region of the shunt using thin sections. The data are then reprocessed a overlapping intervals and various reformations are obtained. Preliminary reports show the sensitivity and specificity of the helical CT angiography to be comparable with Doppler sonography.

Angiography↗
PubMed1999

Diverticulitis versus colon cancer: differentiation with helical CT findings.

PURPOSE: To retrospectively determine the computed tomographic (CT) signs associated with diverticulitis or colon cancer, and to prospectively apply these signs in the differentiation of these diseases. MATERIALS AND METHODS: Fifty-eight CT scans in cases of proved diverticulitis (n = 27) or colon cancer (n = 31) were evaluated retrospectively by radiologists (blinded to the proved diagnosis) for the presence or absence of previously reported CT findings. These findings were correlated with the pathologic or final clinical diagnosis. The retrospective findings were applied in a prospective evaluation with a new set of 72 CT scans. The same five radiologists rendered a diagnosis according to a five-point confidence scale from definitely benign to definitely malignant. Individual and consensus readings were correlated with the final diagnosis. RESULTS: Retrospectively, pericolonic inflammation (P < .01) and segment involvement greater than 10 cm (P < .012) were the most significant findings for diverticulitis; pericolonic lymph nodes (P < .0001) and luminal mass (P < .003) were the most significant findings for colon cancer. Prospectively, an unequivocal diagnosis was made correctly in 16 (40%) of 40 cases of diverticulitis and 21 (66%) of 32 cases of colon cancer. CONCLUSION: When there are no pericolonic lymph nodes adjacent to a segment of colonic wall thickening, with pericolonic inflammatory changes, the most likely diagnosis is diverticulitis. When pericolonic lymph nodes are present, with or without pericolonic edema, the most likely diagnosis is colon cancer.

Colonic Neoplasms↗
PubMed1999

End-stage primary sclerosing cholangitis: CT findings of hepatic morphology in 36 patients.

PURPOSE: To determine if there is a significant difference in the hepatic morphology depicted on computed tomographic (CT) scans in patients with end-stage cirrhosis caused by primary sclerosing cholangitis versus that in patients with end-stage cirrhosis caused by other factors. MATERIALS AND METHODS: The frequency of five morphologic findings of the liver parenchyma and two intrahepatic biliary findings identified on CT scans in 36 patients with end-stage cirrhosis caused by primary sclerosing cholangitis were compared with the frequency of the same findings in 472 patients with end-stage cirrhosis caused by other factors. The morphologic findings were lobulation of the liver contour, atrophy of the lateral or posterior hepatic segments, hypertrophy of the caudate lobe, and pseudotumor of the caudate lobe. Lobulation, atrophy, and hypertrophy were subclassified as mild-moderate or severe. The biliary findings were ductal dilatation and calculi. RESULTS: Each of the 11 findings occurred more frequently (P < .05) in patients with primary sclerosing cholangitis than in the other 472 patients. Six findings occurred more frequently (P < .05) in patients with primary sclerosing cholangitis than in patients with cirrhosis caused by any other single agent. CONCLUSION: There is a significant difference in the hepatic morphology observed in patients with primary sclerosing cholangitis-induced end-stage cirrhosis versus that in patients with end-stage cirrhosis of other causes.

Adolescent↗
PubMed1999

Mesenteric, omental, and retroperitoneal edema in cirrhosis: frequency and spectrum of CT findings.

PURPOSE: To determine the frequency and CT imaging spectrum of mesenteric, omental, and retroperitoneal edema in patients with cirrhosis. MATERIALS AND METHODS: Eighty patients were identified with liver cirrhosis and no other cause of edema. Five radiologists jointly reviewed the abdominal CT scans of these patients to assess, by majority decision, the presence, severity, distribution, and configuration of mesenteric edema and the presence of omental and retroperitoneal edema. Subcutaneous edema, ascites, pleural effusion, splenomegaly, varices, portal venous thrombosis, and serum albumin levels were also documented. RESULTS: Mesenteric edema was present in 69 (86%) patients. Mesenteric edema occurred alone in 26 (38%) and with omental or retroperitoneal edema in 40 (58%) of the 69 patients with edema. No patient had omental or retroperitoneal edema alone. Mesenteric edema was mild in 51 (74%) and moderate to severe in 18 (26%), patchy in 47 (68%) and diffuse in 22 (32%), purely infiltrative in 60 (87%) and infiltrative with superimposed masslike nodules in nine (13%) patients. These parameters had significant associations among themselves and with ascites, pleural effusions, subcutaneous edema, and low mean serum albumin levels but not with splenomegaly or varices. CONCLUSION: Mesenteric, omental, and retroperitoneal edema occur commonly in patients with cirrhosis. The appearance of mesenteric edema varies from a mild infiltrative haze to a severe masslike sheath that engulfs the mesenteric vessels.

Adult↗
PubMed1999

Spectrum of imaging findings of the liver in end-stage cirrhosis: Part II, focal abnormalities.

Cirrhosis, through the process of necrosis, fibrosis, regeneration, and malignant transformation, creates multiple focal benign and malignant hepatic masses. The detection and appearance of these masses varies with the severity of the cirrhotic process and the imaging technique used. Although some overlap exists in the imaging appearance of the benign and malignant masses, in most instances recognition of a few characteristic features will yield the correct diagnosis.

Carcinoma, Hepatocellular↗
PubMed1999

Anesthetic considerations in patients undergoing percutaneous radiofrequency interstitial tissue ablation.

Radiofrequency (RF) interstitial tissue ablation is a new, minimally invasive procedure for patients with liver cancer who are not candidates for conventional therapy. The percutaneous RF ablation therapy involves placing a needle electrode under ultrasound guidance into a selected portion of the tumor and heating the tissue between 90 degrees C and 100 degrees C. The ablation procedure can be done under monitored anesthesia care on an outpatient basis. The patient's ability to cooperate with regard to breathing is critical for accurate needle placement. Intravenous sedation must be meticulously titrated to maintain a delicate balance of patient cooperation and optimal comfort.

Anesthesia↗