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Biomedical subjects

R A Halvorsen

Publications and source records attributed to R A Halvorsen.

At least 19 recordsLinked to original sources
PubMed1992

Safety considerations in the power injection of contrast media via central venous catheters during computed tomographic examinations.

RATIONALE AND OBJECTIVES: This study addresses the theoretical, experimental, and clinical application of using a central venous catheter system (CVS) for the rapid injection of contrast media during computed tomography (CT). METHODS: Application of Poiseuille's law and the Reynolds equation yielded theoretical data. In-line pressures were measured in experimental models and patients undergoing CT. Diatrizoate meglumine and iohexal contrast media were evaluated. RESULTS: The Reynolds number was consistent with laminar flow, allowing the application of Poiseuille's law. The calculated and experimental catheter tubing-chamber connection pressures were safe for both contrast media, at rates of 1 mL/second for long catheter tubing and 2 mL/second for short tubing. Thirteen patients had measured pressures within safety limits with no complications. CONCLUSIONS: This study establishes that power injection of contrast media via a CVS during CT is a safe procedure. Benefits include no need for peripheral intravenous catheter placement, decreased paramedical staff radiation exposure, and improved CT image quality.

Catheterization, Central Venous↗
PubMed1992

Imaging of the pharynx and esophagus.

The year 1991 was a year of innovation, with interesting papers published in the imaging as well as the medical and surgical literature. Several reports described novel techniques using transcutaneous ultrasound to evaluate the swallowing mechanism; another used CT and ultrasound of the neck for staging esophageal carcinoma. The new field of endoscopic ultrasound was again a subject of much investigation and was compared with CT in the staging of esophageal cancer. One study suggested that endoscopic ultrasound was superior to CT in staging esophageal cancer whereas another found that endoscopic ultrasound had an accuracy rate of only 59% in detecting local invasion. MR imaging and CT were reevaluated for staging esophageal carcinoma using criteria that were modified slightly from previous techniques. These new criteria simplified the detection of aortic and pericardial invasion and staged esophageal carcinoma accurately. The definition of "normal" was refined this year. For instance, in a study of swallowing in asymptomatic and presumably normal elderly individuals, a number of findings were encountered that are considered abnormal in the younger patient. Another study documents normal swallowing patterns in the infant. Other papers provided refinements in radiographic examination techniques as well as excellent reviews of anomalies, esophagitis, and the management of esophageal foreign bodies. The review is divided into two sections that discuss the pharynx and the esophagus.

Diagnostic Imaging↗
PubMed1991

Primary neoplasms of the hollow organs of the gastrointestinal tract. Staging and follow-up.

The number of imaging modalities available to stage and follow-up patients with primary neoplasms of the gastrointestinal (GI) tract continues to increase. Magnetic resonance imaging (MRI), computed tomography (CT), and ultrasonography are useful techniques for both staging and follow-up. For staging, CT is most frequently used for the detection of liver metastases and is increasingly used as a substitute for the chest radiograph in the detection of lung metastases. CT is still the imaging test of choice for the preoperative staging of esophageal carcinoma. CT is less helpful in staging the patient with gastric carcinoma or colorectal carcinoma. The current usefulness of MRI in the staging of GI tract malignancies is limited by the lack of an adequate oral intraluminal contrast agent and degradation of images due to motion. Sonography, especially the new technique of endoscopic ultrasound, is promising for the detection of local invasion from GI tract malignancies. CT is used in the follow-up of patients with tumors of the GI tract to detect liver, adrenal, and nodal metastases as well as local recurrence because of the ability of CT to detect extraluminal masses. CT of the pelvis has been recommended as a routine follow-up procedure in patients who have undergone abdominal-peroneal resection. Both CT and MRI can be used to detect local recurrence, but suffer from the inability to differentiate scar from recurrent tumor. The initial hope that MRI would be capable of differentiating postoperative scar tissue from recurrent tumor has not been realized. Therefore, with positive CT or MRI findings, occasionally a percutaneous biopsy will be required to confirm local recurrence.

Diagnostic Imaging↗
PubMed1991

Ectopic splenomegaly in Felty's syndrome.

A 50-year-old woman with Felty's syndrome, who presented with "menopausal" symptoms, was found to have a large pelvic mass on physical exam. Computed tomography of the pelvis led to an incorrect diagnosis of malignancy, while radionuclide imaging using Tc-99m sulfur colloid confirmed the diagnosis of ectopic splenomegaly.

Choristoma↗
PubMed1991

Obliterative bronchiolitis following lung transplantation. Diagnostic utility of aerosol ventilation lung scanning and high resolution CT.

A serious and often fatal complication of heart-lung transplantation is the development of obliterative bronchiolitis (OB). Currently the screening for OB is based on symptoms, pulmonary function tests, and transbronchial biopsies. The chest radiographs are often normal with OB. Obliterative bronchiolitis produces luminal narrowing of both bronchioles and bronchi resulting in areas of peripheral consolidation and occasional bronchiectasis. We report a patient in whom a chest film was normal, an aerosol ventilation lung scan was abnormal while a perfusion study was mildly abnormal. Simultaneously, routine CT was essentially normal while high resolution CT with 1 mm thick sections was clearly abnormal and demonstrated areas of consolidation. These imaging modalities detected clear-cut abnormalities at a time when the patient was symptomatic but prior to the development of demonstrable abnormality on chest radiograph.

Adult↗
PubMed1991

The use of iohexol in patients with previous reactions to ionic contrast material. A multicenter clinical trial.

Patients who have had prior reactions to iodinated contrast material have increased risk for repeat reactions. Nonionic contrast agents have been reported to reduce the risk of contrast reactions. A multicenter study was undertaken to determine the repeat reaction rate using iohexol. Two hundred ninety-one repeat reactors were included in the study, of whom one-third received premedication. Sixteen patients (5.5%) experienced repeat reactions; none was severe, and only one was more serious than the prior reaction. This is in contrast to the reported 16% to 44% repeated reaction rate for ionic agents. We conclude that iohexol is effective in reducing the occurrence of repeat reactions from the level observed with ionic agents without premedication. Iohexol appears to be as effective as ionic agents plus premedication in this high-risk group of patients.

Adult↗
PubMed1991

Chest-wall deformity after tissue expansion for breast reconstruction.

A prospective longitudinal study of chest-wall deformity after tissue expansion for breast reconstruction was performed in 19 women. CT imaging was a sensitive method for detecting occult deformity. Using a semiquantitative scale for measuring deformity, all patients and 94 percent of expanders had some thoracic abnormality after tissue expansion. Rib and chest-wall contour changes were observed under 81 and 68 percent of the expanders, respectively. Routine chest roentgenograms were not a sensitive method for evaluating these deformities. The magnitude of deformity after unilateral expansion was not significantly different from that after bilateral expansion. Linear regression analysis indicated that early periprosthetic capsular contracture was negatively correlated with chest wall deformity. Only one patient experienced a clinically noticeable complication from chest compression--transient postexpansion exertional dyspnea. After removing the expanders and placing permanent implants along with capsulotomy, the mean deformity index decreased by 57 percent after 10.5 months median follow-up, which was highly significant (p less than 0.001). Our findings suggest that chest-wall deformity is a common occurrence after tissue expansion in patients undergoing breast reconstruction and is usually of minor clinical significance.

Female↗
PubMed1991

Intraperitoneal contrast material improves the CT detection of peritoneal metastases.

The preoperative detection of peritoneal metastases from gynecologic malignancies is difficult; in particular, CT often fails to detect peritoneal implants. This study was designed to determine if the administration of intraperitoneal iodinated contrast media would increase the CT detection of such peritoneal metastases. Prospectively, both standard and intraperitoneal contrast-enhanced CT studies of the abdomen and pelvis were performed in 16 patients with suspected gynecologic tumors. All patients then underwent operative staging, with the location and number of metastases documented. The intraperitoneal enhanced CT studies were more sensitive in the detection of peritoneal metastases than standard CT examinations. Whereas routine CT detected peritoneal metastases in seven (64%) of 11 patients with surgically proved implants, the intraperitoneal enhanced CT studies detected peritoneal metastases in all 11 patients. Depending on the specific intraperitoneal compartments involved, the sensitivity of intraperitoneal enhanced CT in the detection of peritoneal metastases was two- to fourfold greater than that of standard CT examinations. Our results suggest that intraperitoneal enhanced CT is superior to standard CT in the detection of peritoneal metastases.

Diatrizoate Meglumine↗
PubMed1991

Imaging of the pharynx and the esophagus.

In the past year there have been an unusual number of new concepts developed concerning the pharynx and the esophagus. The normal swallowing mechanism has been studied in detail using a variety of techniques that have increased our understanding of the normal and abnormal swallowing mechanism. In the esophagus, simultaneous barium swallows and esophageal manometry have created new insights into esophageal peristalsis. Based on this material, new recommendations have been developed for a standard barium swallow for the evaluation of esophageal motility. Also, findings previously considered to be abnormal, such as mild tertiary contractions, have now been demonstrated to be within normal limits. For the first time, detailed criteria for abnormal esophageal peristalsis have been described. This article reviews the literature, emphasizing those areas in which new concepts will affect the practicing radiologist.

Diagnostic Imaging↗
PubMed1991

Imaging primary and metastatic cancer of the liver.

Either CT or MRI can be used as a primary screening test for liver masses in a patient with a known or suspected malignancy. A number of variations in techniques are available for both CT and MRI, and combinations of these techniques are often required to increase the detectability rate for hepatic lesions. Whether CT or MRI is chosen as an initial screening technique depends upon the particular patient and the institution. After a liver lesion has been identified, attempts should be made to obtain a specific diagnosis. Certain liver masses may have a specific CT appearance, especially when they are calcified. With some benign lesions a specific diagnosis is possible using imaging techniques, and in these instances CT and a supplemental radionuclide study may be of complimentary value. These include cavernous hemangioma, focal fatty liver, and focal nodular hyperplasia. Another group of lesions have a CT or an MRI appearance that is suggestive for a specific diagnosis, but may require confirmation with a biopsy or other tests. These include hepatoma, which may present as a mass with portal vein thrombosis, hepatic adenoma, which may appear as a mass with central hemorrhage, focal nodular hyperplasia may occur as a mass with a central stellate scar (on CT), or a cavernous hemangioma, which fulfills specific CT or MRI criteria. A final group of lesions consists of masses without a characteristic or suggestive CT or MRI appearance. These lesions will require biopsy for final diagnosis.

Humans↗
PubMed1990

Sensitivity and specificity of computed tomography for the detection of adrenal metastatic lesions among 91 autopsied lung cancer patients.

The ability of computed tomography (CT) to detect metastatic lesions in adrenal glands was evaluated on 91 autopsied lung cancer patients who died in 11 hospitals in the eastern United States and Canada from January 1983 to February 1988. Abdominal CT scans within 90 days of death were reviewed twice by two radiologists blinded to the autopsy diagnosis. The likelihood of metastatic spread in each adrenal gland was scored on a five-level scale. Histopathologic findings at autopsy were used to establish the presence or absence of metastases. The sensitivity of CT was low. Among 53 adrenal glands with proven metastatic lesions, the proportion with positive CT scans varied from 20.0% to 41.1%, according to the positivity threshold. In contrast, the specificity of CT was high, even at relaxed positivity thresholds, from 84.5% to 99.4%. The relatively low sensitivity of CT to detect adrenal metastatic lesions is explained to a large extent by the lack of substantial structural changes in many adrenal glands found to have metastases at autopsy. With a strongly positive CT scan, the probability of an adrenal metastatic lesion is high, and confirmatory adrenal biopsy may not be needed in patients with adenocarcinoma and large cell carcinoma.

Adenocarcinoma↗
PubMed1990

Cystic central necrosis of transplanted pancreas.

The computed tomographic (CT) findings in pancreas transplant rejection have been reported to include graft swelling and inhomogeneity. We report a patient with transplant rejection in whom the preoperative CT examination and specimen radiographs revealed large cystic structures within the pancreas. Cystic central necrosis has previously been reported in patients with pancreatitis, but here it is associated with transplant rejection.

Adult↗
PubMed1990

Detection of pancreatic fluid and urine leakage after pancreas transplantation: value of CT and cystography.

Leakage from the urinary bladder or duodenal stump after pancreas transplantation with urinary bladder drainage of the graft is difficult to diagnose clinically. We retrospectively reviewed our experience with fluoroscopic cystography and CT to determine their relative merit in the diagnosis of pancreatic fluid and urine leakage as documented by surgical exploration in pancreas transplant recipients. Thirteen leaks were diagnosed by fluoroscopic cystography or by CT in 11 patients after pancreas transplantation with urinary bladder drainage of pancreatic fluid. Conventional retrograde fluoroscopic cystography showed 11 leaks; CT with retrograde bladder opacification showed three leaks. Of the five CT studies that did not show a leak and that also were done within 7 days of a cystogram with abnormal findings, failure to use retrograde bladder opacification accounted for the majority (three cases) of missed diagnoses. Focal or free peritoneal abdominal fluid was seen in all CT examinations, with extravasation of contrast material seen into both walled-off collections and free ascites. Our experience suggests that retrograde bladder and duodenal stump opacification should be a routine part of the CT evaluation performed to detect leakage from the urinary bladder or duodenal stump after pancreas transplantation.

Anastomosis, Surgical↗
PubMed1990

Cytomegalovirus pneumonia: computed tomography findings.

Cytomegalovirus (CMV) is a frequent pathogen of the respiratory tract in immunosuppressed patients. The diagnosis of CMV pneumonia frequently requires bronchopulmonary lavage or lung biopsy because the findings on chest radiographs are nonspecific. In only three cases of pure CMV pneumonia has the computed tomography (CT) appearance been described. In this study CT scans and chest radiographs of eight patients with CMV pneumonia were evaluated to determine if a characteristic CT appearance exists. The studies were evaluated for the type, severity and distribution of parenchymal abnormality. The most common CT finding was the presence of mixed alveolar and interstitial disease (seven patients); alveolar disease predominated in five of the seven patients, equal amounts of alveolar and interstitial disease were noted in one and interstitial disease predominated in the remaining patient. Air-space disease alone was present on CT examination of the eighth patient. In no case was there interstitial disease alone. Although mixed alveolar and interstitial disease was the most frequently encountered pattern, the variety of appearances suggests that the CT findings of CMV pneumonia are nonspecific.

Adolescent↗
PubMed1990

Pseudo-intracardiac air in a heart-lung transplant patient.

Air in the heart is a serious condition and may be life-threatening. It is usually of iatrogenic origin or the result of trauma. Computed tomography of a heart-lung transplant recipient who had unilateral hydropneumothorax revealed a mediastinal gas collection that appeared to be intracardiac. A follow-up study with intrapleural contrast medium revealed that the gas was not within but was actually between cardiac chambers. Consequently the gas collection mimicking intracardiac air was of no clinical importance.

Adult↗
PubMed1989

Reversible hyperinflation in emphysema.

Pulmonary emphysema results in hyperinflation of the lungs and concomitant changes in the configuration of the thoracic cavity. We describe a patient who underwent bilateral lung transplantation for emphysema due to alpha 1 antitrypsin deficiency. Dramatic changes in chest dimensions and configuration occurred following transplantation, demonstrating the dynamic and reversible nature of the thoracic cavity abnormalities of emphysema.

Adult↗