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R F Thoeni

Publications and source records attributed to R F Thoeni.

At least 19 recordsLinked to original sources
PubMed1992

Imaging of the liver.

The liver continues to be a focus for various imaging methods, but MR imaging received most of the attention with new sequences or modifications of older techniques. Primary and secondary focal liver lesions were studied using various techniques, and most researchers agreed that characterization of lesions is the domain of MR imaging. For actual detection of lesions, particularly for number and size of lesions, CT, especially CT during arterial portography, was still considered the methods of choice. Innovative approaches included three-dimensional image analysis of metastases for segmental localization and fusion of images from several cross-sectional studies for improved characterization of lesions. Assessment of fatty infiltration in the liver was investigated using both CT and MR imaging, but the definitive role of cross-sectional imaging for this purpose is not yet established. Evaluation of venous vascular systems was also investigated using both color Doppler ultrasound and MR imaging, but the role of these techniques vis-á-vis each other needs further definition. Spectroscopy continued to advance but current limitations in localization and processing techniques prevented an enthusiastic endorsement by clinicians. Its potential for assessment of tumor response to chemotherapy is substantial.

Diagnostic Imaging↗
PubMed1991

Enteroclysis and small bowel series: comparison of radiation dose and examination time.

Respective radiation doses and total examination and fluoroscopy times were compared for 50 patients; 25 underwent enteroclysis and 25 underwent small bowel series with (n = 17) and without (n = 8) an examination of the upper gastrointestinal (GI) tract. For enteroclysis, the mean skin entry radiation dose (12.3 rad [123 mGy]) and mean fluoroscopy time (18.4 minutes) were almost 1 1/2 times greater than those for the small bowel series with examination of the upper GI tract (8.4 rad [84 mGy]; 11.4 minutes) and almost three times greater than those for the small bowel series without upper GI examination (4.6 rad [46 mGy]; 6.3 minutes). However, the mean total examination completion time for enteroclysis (31.2 minutes) was almost half that of the small bowel series without upper GI examination (57.5 minutes) and almost four times shorter than that of the small bowel series with upper GI examination (114 minutes). The higher radiation dose of enteroclysis should be considered along with the short examination time, the age and clinical condition of the patient, and the reported higher accuracy when deciding on the appropriate radiographic examination of the small bowel.

Barium Sulfate↗
PubMed1991

Colorectal cancer: cross-sectional imaging for staging of primary tumor and detection of local recurrence.

This review describes the use of cross-sectional imaging in the staging of colorectal carcinoma and detection of local recurrence. The contributions of CT, MR imaging, and sonography are discussed and illustrated. Colorectal carcinoma is the second most common tumor in the United States and the most common cancer in the gastrointestinal tract. The prognosis for patients with this neoplasm is closely related to the extent of tumor at the time of diagnosis. Accurate noninvasive preoperative assessment of tumor stage by one or a combination of radiologic techniques would enable appropriate treatment to be planned in each case. Also, determination of possible tumor recurrence would permit effective monitoring of success of therapy and surgical intervention for recurrent disease before widespread metastasis occurs.

Colonic Neoplasms↗
PubMed1991

Imaging of the liver.

New developments in imaging of the liver have continued during the past year. Ultrasonography, particularly color Doppler applications, and invasive CT techniques are used with increasing frequency. New contrast agents are being tested for improved ultrasonographic detection of liver lesions, and faster imaging sequences and variations on older techniques are innovations in the field of MR imaging. Correlation studies addressed the issue of which are the best-suited imaging methods for the various pathologic changes in the liver.

Diagnostic Imaging↗
PubMed1990

CT detection of asymptomatic pancreatitis following ERCP.

Presence or absence of pancreatitis without symptoms attributable to pancreatitis was assessed by computed tomography (CT) in 31 patients who underwent CT following endoscopic retrograde cholangiopancreatography (ERCP) within a time interval of 0-9 days. Presence or absence of pancreatitis was proven by elevated or normal amylase, and/or surgery, and by symptoms related to pancreatitis. Twenty-five of the patients underwent ERCP without and six with sphincterotomies. Among the six patients, additional procedures included two stent placements, two balloon dilatations, and one basket retrieval. Eleven of 31 patients developed pancreatitis following ERCP. The incidence of pancreatitis was higher in the group with maneuvers (four of six patients or 66.7%) than that without maneuvers (seven of 25 or 28%). Asymptomatic pancreatitis was present in five of 31 patients or 16.1%, and three of these had CT evidence of severe pancreatitis. CT demonstration of pancreatitis following ERCP with or without maneuvers may not always indicate clinically relevant disease.

Acute Disease↗
PubMed1990

The loop-torque maneuver: a method to facilitate intubation for enteroclysis.

The loop-torque maneuver is a simple technique used to facilitate intubation with an enteroclysis catheter. A braided stainless steel guidewire, 26 cm longer than the one provided with the commercially available set, is used. A loop is formed in its proximal end to facilitate torquing if the catheter engages the greater curvature or coils up in the fundus. The loop-torque maneuver led to successful intubation of all patients in this series and produced less discomfort than the double-back maneuver.

Contrast Media↗
PubMed1990

Ileoanal pouches: comparison of CT, scintigraphy, and contrast enemas for diagnosing postsurgical complications.

The value of CT of the pelvis, 111In-labeled leukocyte scintigraphy, and contrast enema (pouchography) for detecting postsurgical complications was assessed in 44 patients with total colectomy, rectal mucosectomy, and ileoanal pouches. Ileoanal pouches were created as reservoirs from an ileal loop that was anastomosed to the dentate line of the anus and stayed connected to the remainder of the ileum. This pouch preserves the normal defecatory pathway and eliminates disease-producing mucosa. A total of 57 sets of examinations revealed 22 cases of normal postoperative findings, 22 of pouchitis, 13 of abscess, and three of fistula. Overall sensitivity for detecting complications with pouchography was 60% (18 of 30 findings); with CT, 78% (28 of 36 findings); and with scintigraphy, 79% (23 of 29 findings). Pouchitis was best diagnosed by scintigraphy (sensitivity, 80%), followed by CT (sensitivity, 71%) and pouchography (sensitivity, 53%). Only CT correctly diagnosed all cases of abscess. Fistulas were frequently missed by all three methods. If tests were combined, the overall sensitivity rose to 93% for the combination CT/scintigraphy and to 86% for CT/pouchography, but did not improve for pouchography/scintigraphy (78%). For evaluation of complications in patients with ileoanal pouches, CT should be the initial test. If an abscess is found, no further tests are needed. If CT findings are negative, a scintigram should be obtained. Our data did not establish a clear role for pouchography.

Abscess↗
PubMed1989

Hepatic neoplasia: breath-hold MR imaging.

Twenty-seven patients with hepatic neoplasms were prospectively examined at 0.35 T with multisection magnetic resonance (MR) imaging during a single breath hold. The procedures included a spin-echo (SE) sequence with a repetition time (TR) of 250 or 125 msec and an echo time (TE) of 15 msec (TR/TE = 250 or 125/15) and gradient-echo (GRE) partial-flip sequences at 250 or 125/20 in phase and 250 or 125/12 out of phase (flip angle of 70 degrees). These procedures were compared with conventional multiacquisition sequences at SE 250/15 (n = 8) in the same patients. GRE partial-flip sequences with a large flip angle provided the optimum combination of contrast and signal-to-noise ratio for imaging hepatic neoplasms, with a signal-difference-to-noise ratio that for in-phase images was 93% greater and for out-of-phase images was 53% greater than that of the SE images. The use of in-phase TEs was preferable to maintain tissue contrast, and presaturation pulses were employed to eliminate vascular pulsation artifacts. All breath-hold procedures provided suppression of motion artifacts superior to that of the short TR, short TE multiacquisition SE imaging. Such sequences should become indispensable for MR imaging of the upper abdomen.

Humans↗
PubMed1989

MR appearance of the liver after partial hepatectomy.

To define the MR appearance of the liver after partial hepatectomy, we reviewed retrospectively 61 MR examinations performed on 25 patients 10 days to 48 months after surgery. Twenty-seven partial hepatectomies performed in the 25 patients included right lobectomy in 11, trisegmentectomy in two, left lobectomy in five, and wedge resection in nine. By using vascular landmarks, demonstration of the falciform ligament, and the presence of surgical clips, we correctly identified the type of partial hepatectomy in 21 of the 25 patients. The signal intensity of the resection margin was similar to that of the remaining parenchyma in 16 of 18 patients and was poorly defined and had a higher signal intensity (T2-weighted image) in the remaining two. Liver regeneration was observed on serial MR scans 2-16 months after surgery. Findings related to chemotherapy, including periportal changes and inhomogeneous appearance of the liver, were shown in six of eight patients. Tumor recurrence was present in nine patients, either intrahepatic (seven patients) or at the resection margin (two patients), and was consistently identified with MR imaging. The ability of MR imaging to produce images without artifacts from surgical clips is helpful in displaying the MR appearance of the liver after partial hepatectomy. Anatomic landmarks, findings related to chemotherapy, and tumor recurrence were shown well.

Adolescent↗
PubMed1989

CT evaluation of carcinomas of the colon and rectum.

Computed tomography (CT) has proved to be a powerful tool in the detection and staging of carcinomas of the colon and rectum. It is unsurpassed in the detection of recurrent colon cancer and is particularly useful in patients who have undergone abdominal-perineal resections for rectal neoplasms. The current applications of CT in colon cancer are contrasted with barium studies, endoscopy, and magnetic resonance imaging.

Colon↗
PubMed1989

MRI of the gastrointestinal tract.

Magnetic resonance imaging (MRI) of the gastrointestinal tract may be useful for detection of inflammatory and neoplastic processes and staging of neoplasms. Successful application of MRI depends upon the use of proper gut contrast material, glucagon, and scan sequences that diminish the effect of respiratory motion. Current uses of MRI center on the evaluation and staging of rectal tumors and on the distinction between recurrent tumor and fibrosis.

Digestive System↗
PubMed1989

Small bowel.

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Barium Sulfate↗
PubMed1988

Detection and staging of renal neoplasms: a reassessment of MR imaging.

The use of magnetic resonance (MR) imaging in the detection and staging of renal neoplasms was investigated in 104 patients with 106 renal cell carcinomas confirmed at surgery or autopsy. Overall, MR imaging demonstrated 101 of 106 lesions (95%), including all 93 tumors that were larger than 3 cm in diameter but only eight of the 13 smaller tumors (62%). MR imaging enabled accurate staging of 82% of all detected lesions but led to the understaging of nine lesions and the overstaging of nine. At present, MR imaging cannot be used as a screening modality for renal tumors. However, its negative predictive values of 98% and 99%, respectively, for the evaluation of tumor vascular extension and tumor spread to adjacent structures makes it an excellent staging modality that should be used when the CT findings are equivocal. MR imaging is not accurate in indicating bowel and mesentery involvement, but rapid technical advances and the introduction of bowel contrast medium may improve this present limitation.

Adult↗
PubMed1988

The state of radiographic technique in the examination of the colon: a survey in 1987.

Results of an extensive multiple-choice questionnaire sent to 175 leading medical centers in the world were analyzed and compared with those of a similar survey from 1976. One hundred sixty-two (93%) responses were received. Both single- and double-contrast enema procedures are still employed, but the use of the double-contrast technique has markedly increased. Preparation of the colon is even more meticulous than in 1976 and is equal for both techniques. Pharmacologic aids are used more often but preparatory enemas less frequently than in 1976. The use of fluoroscopic equipment has not significantly changed. The decision on the appropriate sequence for the barium enema examination and colonoscopy is based on the individual clinical problem in the majority of cases, and the time interval between the barium enema examination and lower endoscopy with or without biopsy is significantly shorter than in 1976. The use of computed tomography and magnetic resonance imaging has increased since 1976, but angiography is used less often and mostly for unknown causes of bleeding and to stop bleeding.

Barium Sulfate↗
PubMed1988

Abdominal and pelvic CT: use of oral metoclopramide to enhance bowel opacification.

The value of orally administered metoclopramide hydrochloride to enhance bowel opacification during abdominal and pelvic computed tomography (CT) was analyzed prospectively in 202 patients in a control group and 334 patients in an experimental group who received 10 mg of metoclopramide with the first dose of oral contrast material. Five hundred milliliters of 2% sodium diatrizoate was given orally 45-60 minutes and 30 minutes before the study, and 250 mL was given 5-10 minutes before the study. Opacification of stomach, duodenum, and small and large bowels was graded from 0 to 3+, and the presence of pseudotumors or side effects from metoclopramide were noted. No significant difference was found in the opacification of stomach, duodenum, and jejunum between control and experimental studies. Opacification was significantly better in metoclopramide studies than control studies in the proximal ileum (P less than .05), distal ileum (P less than .05), right colon (P less than .05), and transverse colon (P less than .05). Pseudotumors were seen in 7% of control and 3% of experimental subjects. No side effects were encountered. Routine oral administration of metoclopramide before abdominal and pelvic CT examinations is recommended for rapid opacification of the ileum and proximal colon for all outpatients and for inpatients who must undergo CT on an emergency basis.

Administration, Oral↗