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M K Thorsen

Publications and source records attributed to M K Thorsen.

At least 19 recordsLinked to original sources
PubMed1993

Periportal halo: a CT sign of liver disease.

Periportal halos are defined as circumferential zones of decreased attenuation identified around the peripheral or subsegmental portal venous branches on contrast-enhanced computed tomography (CT). These halos probably represent fluid or dilated lymphatics in the loose areolar zone around the portal triad structures. While this CT finding is nonspecific, it is abnormal and should prompt close scrutiny of the liver in search of an underlying etiology. Periportal halos which may be due to blood are commonly seen in patients with liver trauma. Periportal edema may cause this sign in patients with congestive heart failure and secondary liver congesion, hepatitis, or enlarged lymph nodes and tumors in the porta hepatis which obstruct lymphatic drainage. This CT sign has also been observed in liver transplants (probably secondary to disruption and engorgement of lymphatic channels) and in recipients of bone marrow transplants who might develop liver edema from microvenous occlusive disease. While the precise pathophysiologic basis of periportal tracking has not been proven, it represents a potentially important CT sign of occult liver disease.

Humans↗
PubMed1993

[Aortic traumatic lesion. Has tomodensitometry a role?].

The low positive yield from aortography in patients with suspected traumatic aortic rupture has prompted research into CT of the mediastinum as a screening investigation which could significantly reduce the number of negative angiograms performed. Much of the data published to date suggest a promising role for CT, but false negative scans have been reported and the precise false negative rate has yet to be determined. We propose an algorithm for the use of CT in suspected traumatic rupture but emphasise that continuous monitoring of outcomes and further large studies are required before CT can become an established screening technique.

Aorta↗
PubMed1992

Imaging of regional spread of breast cancer by internal mammary lymphoscintigraphy, CT, and MRI.

Forty women with breast cancer underwent imaging by internal mammary lymphoscintigraphy (IMLS), which was correlated with the results of CT and MRI of the chest. IMLS was performed and interpreted using the previously described methods of Ege. It identified 22 instances of ipsilateral internal mammary nodal involvement, none of which corresponded to cases of abnormally enlarged (diameter greater than 1.0 cm) internal mammary nodes on CT and/or MRI. Positive IMLS was associated with axillary nodal metastases in 15 out of 22 instances. The authors conclude that IMLS provides information on regional nodal spread of breast cancer that is not available with either CT/MRI imaging or axillary biopsy.

Antimony↗
PubMed1991

Computed tomography in the evaluation of the aorta in patients sustaining blunt chest trauma.

Computed tomography is used with increasing frequency to evaluate blunt chest trauma. Since traumatic aortic rupture (TAR) is a rapidly lethal condition, unnecessary CT scanning may not be justified. To determine the accuracy of chest CT scanning for TAR, we reviewed 17 patients who underwent both chest CT scanning and aortography. Five patients had TAR by aortography. CT scanning yielded three true positives and two false negatives. In 12 patients with a negative aortogram, CT scanning recorded four false positives and eight true negatives. The specificity was 23% and the sensitivity was 83% compared with aortography. The overall accuracy for CT scanning was 53%. From these data we conclude that in the presence of an unstable patient or where there is a strong clinical suspicion of TAR the patient should proceed directly to aortography.

Adult↗
PubMed1990

Diagnosis of ectopic pregnancy: endovaginal vs transabdominal sonography.

During a 25-month period, 193 women with the clinical diagnosis of suspected ectopic pregnancy had transabdominal and endovaginal sonograms. Most had quantitative determinations of serum human chorionic gonadotropin (HCG). Endovaginal sonography was diagnostic of ectopic pregnancy in 23 (38%) of the 60 patients with surgically proved ectopic pregnancies: transabdominal sonography was diagnostic in 13 patients (22%). All 83 intrauterine pregnancies were identified with endovaginal sonography, compared with 34 identified with transabdominal sonography. Endovaginal sonography was somewhat more helpful in the diagnosis of missed abortion and blighted ovum. Eighty endovaginal sonograms were classified as indeterminate as compared with 141 transabdominal studies. This indeterminate group included patients with complete abortions, ectopic pregnancies without sonographic evidence of an extrauterine gestation, incomplete abortions, and patients with subsequent negative serum levels. As in prior reports, endovaginal sonography was superior to transabdominal sonography in the evaluation of suspected ectopic pregnancies. Overall, endovaginal sonography was diagnostic in 113 patients, whereas transabdominal sonography was diagnostic in 52 patients. The finding of an extrauterine fetal pole or embryo was diagnostic for an ectopic pregnancy. Pelvic fluid, the appearance of the endometrium, and a single positive serum HCG determination were not helpful in making the diagnosis of ectopic pregnancy.

Abdomen↗
PubMed1989

Dose to the cardiac vascular and conduction systems in primary breast irradiation.

Using computerized tomography (CT) in which cardiac anatomy was defined, doses delivered to the cardiac compartments, vascular and conduction systems were assessed for various standard techniques of primary breast irradiation. Included in the analysis were 6 MV photon tangents (T) alone, or in conjunction with a separate internal mammary field (IMF). Beams evaluated in the IMF were 6 MV photons, 12 MeV electron beam, and mixed photon/electron beam; Cobalt 60 was also analyzed as an alternate photon beam. Treatment of the IMF with photons, either alone or in combination with electron beam, delivered doses ranging between 30 Gy to 50 Gy to all chambers of the heart, coronary arteries and branches of the conduction system. Complete sparing of the posterior cardiac structures and volume is accomplished with treatment plans using tangents alone or in combination with 12 MeV electron beam irradiation to the IMF. Sparing of the anterior wall of the left ventricle, Bundle of His and left anterior descending coronary artery is also achieved in treatment with tangents and 12 MeV electron beam IMF. Doses to this region with tangents alone ranged from 20 Gy to 45 Gy compared to 0 to 30 Gy with tangents and 12 MeV electron beam IMF. Clinical significance of these findings will be discussed.

Breast Neoplasms↗
PubMed1989

Inability of sonography to detect imminent ovulation.

Sonographic visualization of the cumulus oophorus or of morphologic alterations in the wall of the dominant follicle have been reported to be reliable signs of imminent ovulation when conventional transabdominal sonography is used. To determine if transvaginal sonography could allow a more frequent and confident prediction of imminent ovulation, we prospectively monitored 22 ovulatory menstrual cycles in four women undergoing artificial insemination and in 13 normally menstruating volunteers. Scanning was done on alternate days in the periovulatory period; a 7.5-MHz transvaginal transducer was used. Despite the improved resolution obtained with transvaginal sonography, confident identification of the cumulus oophorus or of mural changes in the follicle was not possible in any of the cycles followed. No other consistent follicular characteristic predicted imminent ovulation. We conclude that confident prediction of imminent ovulation is not possible with sonographic analysis.

Adult↗
PubMed1989

Prospective comparison of radionuclide, computed tomographic, sonographic, and magnetic resonance localization of parathyroid tumors.

The appropriate choice of imaging techniques to localize parathyroid tumors preoperatively remains controversial. We report the first prospective, blinded study to compare the efficacy of four imaging modalities in 100 patients with primary hyperparathyroidism (pHPT). Patients were examined by computer-assisted thallium 201/technetium 99m subtraction scintigraphy (TTS), computed tomography (CT), ultrasonography (US), and magnetic resonance (MR). Each study was performed and interpreted independently. Subsequent neck exploration and "curative" parathyroidectomy allowed correlation of surgical findings with imaging reports to score their accuracy. Overall sensitivities of the four imaging modalities were TTS, 73%, CT, 68%, US, 55%; and MR, 57%; with respective specificities of 94%, 92%, 95%, and 87%. Sensitivities for lesions located below the thyroid gland (thymic tongue and mediastinum) were TTS, 90%; CT, 46%; US, 44%; and MR, 50%; with respective specificities of 100%, 99%, 100%, and 94%. There was a significant increase in overall sensitivity when TTS and CT (90%, p less than 0.01) or TTS and US (85%, p less than 0.05) were used together; however, the combination of any three or even four imaging modalities did not increase sensitivity further. For small parathyroid tumors (less than or equal to 250 mg), no imaging technique had a sensitivity of more than 50%. None of the imaging studies accurately localized small hyperplastic parathyroid glands found in patients with multiple gland disease. Preoperative parathyroid imaging may not be indicated in pHPT patients undergoing first-time neck exploration because surgeons experienced in parathyroid surgery have a 93% to 96% cure rate.

Adult↗
PubMed1988

Computed tomography examination of periampullary neoplasms.

The hospital records of 24 patients with periampullary neoplasms were reviewed. The clinical triad of jaundice, pain, and weight loss and the radiographic imaging triad of dilated biliary ducts, dilated pancreatic duct, and periampullary mass should suggest the diagnosis of periampullary neoplasm.

Adenocarcinoma↗
PubMed1987

Detection of pleural effusions on supine chest radiographs.

A prospective analysis of anteroposterior supine radiographs in 34 patients was undertaken to determine the detectability of pleural effusions on supine radiographs. The presence of pleural effusions and quantity of fluid (small, moderate, or large) were evaluated by using the following radiographic signs: increased homogeneous density superimposed over the lung, loss of the hemidiaphragm silhouette, blunted costophrenic angle, apical capping, elevation of the hemidiaphragm, decreased visibility of lower-lobe vasculature, and accentuation of the minor fissure. Decubitus radiographs were performed to identify and to estimate the quantity of pleural fluid. Sixty-two hemithoraces were evaluated by three observers. From a total of 36 pleural effusions shown on decubitus views, 24 were correctly identified on supine radiographs (sensitivity of 67%, specificity of 70%, and accuracy of 67%). The most frequent but least specific criterion for detecting pleural effusions on supine radiographs is blunting of the costophrenic angle. Other helpful signs include loss of the hemidiaphragm and increased density of the hemithorax. A normal supine radiograph does not exclude a pleural effusion. Our results show that supine radiographs are only moderately sensitive and specific for the evaluation of pleural effusions.

Humans↗
PubMed1987

False-positive CT diagnosis of gallstones due to thickening of the gallbladder wall.

An erroneous CT diagnosis of cholelithiasis was made at our institution during the past year in seven patients who had thickening of the gallbladder wall. In all cases the mucosa, which had a high attenuation value, was misinterpreted as a calcified stone, and the low-attenuation thickened submucosa was misinterpreted as intraluminal bile surrounding the stone. Depending on the attenuation of the actual intraluminal bile, the pseudostone appeared peripherally calcified (five patients) or uniformly calcified (two patients). Careful analysis of the position and configuration of a suspected stone and of the outer margin of the gallbladder can help avoid an incorrect CT diagnosis of gallstones when high-attenuation thickened mucosa simulates a gallstone and low-attenuation submucosa looks like surrounding bile.

Adult↗
PubMed1986

Pituitary and adrenal CT of Cushing syndrome.

Determination of the site of excessive hormone production in Cushing syndrome is possible with biochemical tests in 80% of cases. High-resolution CT of both the pituitary and adrenal glands was used to evaluate eight patients with surgically verified ACTH-secreting pituitary microadenomas and one patient with ectopic Cushing syndrome. Three ACTH-secreting microadenomas were demonstrated by CT. Adrenal CT was normal in six of the eight patients with pituitary tumors. The patient with ectopic ACTH production had mild unilateral adrenal gland enlargement and a normal pituitary CT scan. Normal adrenal or pituitary CT scans do not exclude Cushing syndrome.

Adenocarcinoma↗
PubMed1986

CT of aortic dissections.

Dissecting aortic aneurysms are one of the few medical emergencies where prompt recognition is crucial. Contrast-enhanced computed tomography combined with dynamic scanning offers an excellent noninvasive means to evaluate patients with suspected aortic dissection. At the Medical College of Wisconsin, we retrospectively reviewed all patients who were referred to the Section of Computed Body Tomography with the diagnosis of suspected aortic dissection. Over 100 patients were studied. The sensitivity, specificity, and overall accuracy of computed tomography was greater than 95%.

Adult↗
PubMed1985

Differential diagnosis of low-attenuation splenic lesions on computed tomography.

A retrospective computed tomography evaluation of proved low-attenuation splenic lesions in nontraumatic cases was done. Computed tomography was able to distinguish cystic from solid lesions. Although computed tomography examination is sensitive in the detection of low-attenuation lesions, the computed tomography findings alone are not helpful in differentiation of different low-attenuation lesions. Associated computed tomography findings in other organs and clinical findings are more helpful than the size, shape, and computed tomography attenuation of the lesions. Splenic lesions may be the only metastatic manifestation in some cancer patients. A thin needle aspiration may be done to document the nature of the pathologic lesion in problematic cases.

Abscess↗