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Biomedical subjects

R A Halvorsen

Publications and source records attributed to R A Halvorsen.

At least 55 records · Page 3Linked to original sources
PubMed1988

Hepatic abscess: sensitivity of imaging tests and clinical findings.

The imaging studies of 63 patients with hepatic abscess were evaluated to determine the sensitivity of specific imaging tests and define causes of false-negative test results. Computed tomography (CT) detected 57 of 59 (97%) separate episodes of hepatic abscess. The two false-negative CT examinations were in patients with a diffuse low-density pattern throughout the liver. The radionuclide (RN) examination detected 16 of 20 (80%) cases, missing abscesses less than 2 cm in diameter. Ultrasound detected 33 of 42 (79%) cases, missing abscesses in the dome of the liver, small abscesses, and 2 large early abscesses. For all three imaging modalities, a specific diagnosis of abscess was possible only in those patients in whom CT scans demonstrated abscess gas (15%). The results of the imaging studies were correlated with the patients' clinical condition and laboratory findings. Thirty-one percent of patients were afebrile while 23% had normal white blood cell counts. Thirteen percent had totally normal liver function tests. We conclude that the clinical absence of fever, leukocytosis, or elevated liver function tests does not permit exclusion of the diagnosis of hepatic abscess. A CT scan is highly specific in excluding the diagnosis of hepatic abscess in the absence of diffuse liver disease. In this retrospective study CT was the most sensitive imaging modality available for the detection of hepatic abscess.

Adolescent↗
PubMed1988

Sonography of small renal masses with indeterminant density characteristics on computed tomography.

Nine small renal masses with attenuation coefficients greater than 20 HU on computed tomography (CT) were termed indeterminate for cyst or renal cell carcinoma. Correlative sonography identified the fluid-filled internal architecture in four of five cysts and correctly characterized as solid four small renal cell carcinomas. The sonogram was particularly valuable in assessing masses that were indeterminate on CT when enhancement was equivocal or when intravenous contrast could not be administered. We conclude that sonography is extremely useful as a noninvasive procedure in evaluating the occasional small renal mass with CT number greater than 20 HU.

Carcinoma, Renal Cell↗
PubMed1988

Gastric adenocarcinoma: CT versus surgical staging.

Seventy-five patients with gastric carcinoma underwent preoperative staging with computed tomography (CT). In 14 patients, CT failed to demonstrate lymphadenopathy despite the presence of malignant lymph nodes at surgery. In 13 patients, CT demonstrated enlarged nodes, but no malignant involvement was found at surgery. Although spread to the pancreas was correctly predicted in three patients with lack of fat plane between tumor and pancreas, five patients lacking a fat plane had no invasion, whereas eight patients with an intact fat plane had invasion. Thirty-five patients (47%) were incorrectly staged with CT:23 (31%) were understaged and 12 (16%) were overstaged. CT does not accurately display the true extent of disease in patients with gastric carcinoma and therefore should not be used routinely for staging.

Adenocarcinoma↗
PubMed1987

Carcinoid liver metastases. Accuracy of radionuclide liver/spleen imaging compared to computed tomography.

Carcinoid liver metastases may be more easily detected by radionuclide liver-spleen studies (RN imaging study) than by computed tomography (CT). While multiple studies have suggested that CT is a more sensitive test than the Tc-99m sulfur colloid study for the detection of most types of liver metastases, carcinoid tumors appear to be an exception. The results of 23 pairs of CT and RN imaging studies that were obtained within one month of each other in patients with proven carcinoid tumors are reported. Comparison of the initial reports of the studies as well as a blinded reinterpretation of the studies suggest that in this group of patients the RN imaging study appeared to be superior to CT in the evaluation of the response to therapy.

Carcinoid Tumor↗
PubMed1987

Computed tomographic staging of gastrointestinal tract malignancies. Part I. Esophagus and stomach.

The utility and limitations of CT staging of carcinomas of the esophagus, stomach, small bowel, and colon are reviewed. Routine preoperative staging of esophageal carcinoma is recommended because of CT's sensitivity of more than 90% in detecting mediastinal invasion and a specificity of more than 85% in collected series. We recommend the use of CT as a problem-solving technique rather than as a routine preoperative test in patients with gastroesophageal junction, and gastric and small bowel malignancies. Routine use of CT to stage colorectal carcinomas also does not seem justifiable, due to the inability of CT to determine the depth of bowel wall involvement and to detect tumor in normal size lymph nodes. CT can help differentiate tumors that invade the pelvic side walls from more limited cancers and, therefore, in certain cases can aid in therapy planning. CT is the best method for detecting local recurrence in patients with rectosigmoid carcinomas.

Aortography↗
PubMed1987

Scientific presentations. What to do and what not to do.

An effective scientific presentation requires skill, experience, and effort. In planning the presentation, a skilled speaker first forms clear conclusions through analysis of the data, then tailors the details of the proof of these conclusions to the interests and background of the audience. The facts and conclusions are presented in a practiced, specific, clear, and logical manner. It is not the topic or the data alone, but the sympathetic and strategic communication of the material to a particular audience that makes a meaningful presentation.

Audiovisual Aids↗
PubMed1987

Computed tomography of the rectum.

CT is an important diagnostic procedure in patients with suspected or known disease of the rectum. Knowledge of proper technique for CT of the rectum, as well as an understanding of normal pelvic anatomy, is essential to its effective use. CT can demonstrate the extent of perirectal and pararectal abnormalities detected on barium enema. While routine preoperative staging of rectal cancer is not justified, CT can be used to solve specific problems. Perhaps the most important role of rectal CT is in evaluating postoperative rectosigmoid cancer patients in an attempt to detect early asymptomatic recurrences and, thereby, prolong patient survival.

Abscess↗
PubMed1987

Paracardiac adenopathy: CT evaluation.

To establish the normal CT appearance of lymph nodes in the paracardiac area, we reviewed the CT scans of 50 patients without known malignancy or benign causes of lymphadenopathy. Five patients (10%) showed soft-tissue densities in the paracardiac region. The largest of these measured 3.5 mm. No more than two rounded soft-tissue densities were seen in any of the normal CT studies. Forty-five patients with paracardiac adenopathy were subsequently evaluated. In 27 (60%) of these the masses were due to either carcinoma, sarcoma, or benign disease. In 40%, the cause of paracardiac adenopathy was lymphoma. Features that favor a diagnosis of lymphoma are bilateral disease, multiple nodes, nodes greater than 2 cm in diameter, a lobulated or "matted" appearance, and associated pericardial thickening/effusion. Chest radiographs obtained within 2 weeks of the CT scans in 38 patients revealed only nine cases in which a paracardiac mass could be seen. This study suggests that 1 cm is the upper limit for the diameter of lymph nodes in the paracardiac region, and that paracardiac adenopathy may be caused by a wide variety of nonlymphomatous malignant and benign diseases in addition to lymphoma. Compared with CT, chest radiographs are insensitive for detecting paracardiac lymph node enlargement.

Colonic Neoplasms↗
PubMed1986

CT differentiation of pleural effusion from ascites. An evaluation of four signs using blinded analysis of 52 cases.

Four criteria have been described to differentiate ascites from pleural effusion by computed tomography (CT). These four signs (the diaphragm sign, the displaced crus sign, the interface sign, and the bare area sign) were compared in a retrospective blinded analysis in 52 patients with ascites, right pleural effusion, or both ascites and right pleural effusion. There were limitations with each of the four criteria. Each of the individual criteria was reliable when only one abnormal fluid collection, either pleural effusion or ascites, was present. When both a right pleural effusion and ascites were present, none of the four criteria reliably identified both fluid collections. The combined use of the four criteria, however, led to a correct identification of all the abnormal fluid collections.

Ascites↗
PubMed1986

Centrilobular emphysema: CT-pathologic correlation.

Over a 5-year period, 25 patients who had undergone chest computed tomography (CT) died and were autopsied. Their lungs were fixed in the inflated state and were assessed for the presence and severity of centrilobular emphysema (CLE). Three radiologists independently evaluated the CT scans for nonperipheral low-attenuation areas, peripheral low-attenuation areas, pulmonary vascular pruning, pulmonary vascular distortion, and pulmonary density gradient. The CT criterion that best correlated with the presence and severity of CLE was the nonperipheral low-attenuation area. With this CT criterion, lung destruction was correctly identified in 13 of 15 cases. The absence of this criterion resulted in correct identification of eight of ten normal lungs. These preliminary data suggest that CLE can be reliably identified and quantified with current CT scanners.

Emphysema↗
PubMed1986

Esophageal cancer staging by CT: long-term follow-up study.

To evaluate the utility of computed tomographic (CT) staging in patients with esophageal cancer, the length of patient survival was compared with pretherapy CT findings in 89 patients. Regardless of therapy, patients with evidence of mediastinal invasion, liver metastases, or abdominal adenopathy had a statistically shortened survival (P less than .05). Specific CT criteria that predicted a shortened survival included evidence of tracheal, aortic, or pericardial invasion. Patients with evidence of both mediastinal invasion and abdominal metastases had a mean survival of 180.4 days; those with no evidence, 479.6 days. The presence of enlarged upper abdominal lymph nodes indicated the worst prognosis (mean survival, 90 days). The patients with squamous cell tumors were classified by the CT staging system, and survival data were compared according to surgical procedure. Patients who underwent attempted curative surgery did not have a statistically significant difference in survival by analysis of survival curves but demonstrated a longer mean survival than those who underwent palliative or no surgery.

Adult↗
PubMed1986

Optimal cholangiographic technique for detecting bile duct stones.

Twenty-eight patients with proven bile duct stones were evaluated during either operative or T-tube cholangiography. Two radiographs were obtained for each patient without changing patient position between films. The first was performed with low peak kilovoltage (75-80 kVp) and 15% iodinated contrast medium and the second with high kVp (110) and 38% iodinated contrast. Seven radiologists evaluated the radiographs individually and in matched pairs for ductal filling, ductal penetration, motion unsharpness, overall quality, and stone detectability. The high-kVp radiographs were rated significantly better overall than the low-kVp studies (p less than 0.001) for all five criteria. In the second evaluation, which compared the pairs from the same patients, the 28 high-kVp radiographs were considered superior to the 28 low-kVp studies by the radiologists in almost two-thirds of the comparisons (ductal filling, 68%; penetration, 59%; less motion unsharpness, 65%; overall quality, 77%; stone detection, 62%). On the basis of the results of this study, high-kVp technique with full-strength contrast medium for operative and T-tube cholangiography is recommended.

Cholangiography↗
PubMed1986

Preoperative and postoperative CT staging of rectosigmoid carcinoma.

This study reports a 4 year experience using CT for preoperative staging and for evaluation of patients with rectal and sigmoid carcinoma after surgery. All patients were evaluated on a GE 8800 scanner using 1 cm contiguous slices. Only 15 of the 25 preoperative patients were staged correctly. The other 10 patients were understaged by CT. The accuracy of detecting local invasion was 70%, but only seven (35%) of 20 patients had accurate assessment of lymph nodes. The overall accuracy of CT staging in the 46 postoperative patients was 87%, with a sensitivity of 91% and a specificity of 72%. Most recurrences were found in the pelvis; 16 patients had liver metastases, and metastatic disease obstructing the ureters was detected in eight patients. On the basis of these results, it was concluded that CT should not be used routinely to preoperatively stage patients with rectosigmoid carcinoma. However, all patients who have undergone resection for rectal or sigmoid carcinoma should have aggressive CT evaluation including a baseline study at 2-4 months and then follow-up studies at every 6 months for at least 2 years. All new or enlarging masses should have CT-guided biopsies. This approach may prolong survival by detecting early asymptomatic recurrences.

Adult↗