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Biomedical subjects

M P Frick

Publications and source records attributed to M P Frick.

At least 37 records · Page 2Linked to original sources
PubMed1989

Myocardial uptake and clearance of T1-201 in healthy subjects: comparison of adenosine-induced hyperemia and exercise stress.

Pharmacologic stress testing with dipyridamole is useful in patients undergoing thallium-201 myocardial perfusion scintigraphy who cannot adequately exercise. Because dipyridamole increases coronary blood flow by reducing the metabolism of adenosine, the authors compared the uptake and clearance of T1-201 following exercise stress testing (EST) and resting intravenous infusion of adenosine (AI) in crossover fashion in 20 healthy men. No perfusion defects or areas of redistribution were noted in any of the scans. Mean absolute myocardial T1-201 uptake was 1.3 times greater with AI than with EST. Mean absolute extracardiac uptake was 2.0 times greater with AI. Mean T1-201 myocardial clearance was virtually the same in all AI and EST views. During AI, 70% of the subjects experienced subjective side effects, mean arterial blood pressure decreased by 15%, and heart rate increased by 48%. The effects of adenosine on T1-201 kinetics in the myocardium are similar to those of EST. Adenosine may be useful as a pharmacologic stress agent in patients undergoing T1-201 myocardial perfusion scintigraphy.

Adenosine↗
PubMed1989

Positron emission tomography (PET): a unique approach for the imaging of in vivo metabolism.

Positron Emission Tomography (PET) is a new diagnostic imaging modality which will be available for the study of patients in the greater Nebraska area beginning mid year 1989. This technology will provide unique information on regional function and blood flow in a variety of body organs. Our emphasis will be placed on the identification of the viability of heart muscle in patients suffering a myocardial infarction or following thrombolysis who are being considered for a bypass procedure or angioplasty. We will also use PET to identify epileptic foci and to aid in the diagnosis of Alzheimer's disease, and for the assessment of the efficacy of various treatments of brain and other organ tumors. Despite the relatively high fixed costs of PET, we are confident that the unique information provided by this technology will prove not only to be effacacious but cost effective as well. Thus reimbursement through medical insurance programs, including Medicare, is expected to occur for those studies identified above. Likely coverage for additional PET procedures, particularly in the evaluation of psychiatric disorders, will occur after efficacy and cost effectiveness of these studies have been demonstrated.

Brain↗
PubMed1988

Progressive CT appearance of hepatic metastases from colorectal carcinoma.

An 8-year retrospective review of 106 serial computed tomographic (CT) examinations performed on 32 patients with colorectal carcinoma metastatic to the liver was done to determine if the CT appearance of such metastases changed with a favorable response to chemotherapy or with progression of disease. Of these 32 patients, 15 underwent placement of an infusion pump for delivery of chemotherapy directly into the hepatic artery, 3 underwent partial hepatectomy, 1 underwent both procedures, and 13 underwent neither. Regression of hepatic metastases (7 patients), only seen following infusion pump placement, was associated with a decrease in size and an increase in margination of lesions. In two of these patients regression of metastases was seen in one area of the liver with subsequent progression or development of metastases in another region, presumably due to preferential delivery of chemotherapeutic agent. Progression of disease (23 patients) was associated with an increase in both size and number of lesions that became progressively less well marginated. Development of poorly marginated or infiltrative characteristics at the periphery of the lesion was associated with a poor prognosis. Thus, the CT characteristics of hepatic metastases from colorectal carcinoma differ with a favorable response to chemotherapy and with progression of disease.

Adenocarcinoma↗
PubMed1987

The retropsoas recess. Demonstration using computed tomography.

The retropsoas recess, a previously undescribed normal anatomic variant, is reported. In most individuals, the space posterior to the belly of the psoas muscle contains fat within the posterior pararenal space. However, a retrospective review of 250 consecutive CT examinations of the abdomen revealed 11 cases (4.4%) in which bowel loops extended at least partially posterior to the psoas muscle. Unilateral left-sided occurrence was present in seven, with four bilateral. Colon was invaginated in five, small intestine in four, and both colon and small intestine in one. There was no age or sex predominance. A paucity of retroperitoneal fat is the primary predisposing factor for development of a retropsoas recess. Although recognition of this normal variant is generally not difficult, the CT appearance may mimic a retroperitoneal mass or abscess in less-than-ideal examinations or targeted studies. The potential presence of bowel loops in this location should be considered during interventional procedures.

Adipose Tissue↗
PubMed1987

Liver allograft transplantation: postoperative CT findings.

The CT findings in the abdomen after liver transplantation as seen on 72 examinations in 23 allograft recipients are described. CT was most useful in the evaluation of the gross structural integrity of the allograft and in the detection of extrahepatic fluid collections. Low-density foci within the allograft parenchyma were seen in 10 patients (43%) and were associated with infarction and necrosis, infection, malignancy, and rejection. Localized extrahepatic fluid collections (hematomas, bilomas, and seromas) were present in 16 patients (70%); four of the focal fluid collections detected by CT were infected. Since the nature of these fluid collections could not always be determined by CT characteristics, fine-needle aspiration was sometimes required for a specific diagnosis. Prominence of the portal structures was associated with previous or ongoing episodes of rejection in eight of nine patients, likely reflecting increased resistance to portal flow. CT occasionally showed low, dense, and calcified thrombi in the donor aorta and inferior vena cava. CT also showed biliary obstruction in four patients (17%) without identifying its cause. CT is a noninvasive means of imaging the hepatic allograft recipient; providing data on the hepatic parenchyma, vasculature, and biliary system; and identifying the presence of intraabdominal fluid.

Adolescent↗
PubMed1987

Ultrasound and computed tomographic evaluation in hepatic transplantation.

Ultrasound and CT are valuable in the non-invasive evaluation of complications of hepatic transplantation. Ultrasound is particularly helpful in detecting biliary obstruction and in documenting vascular patency. As with renal transplantation, the value of US in the assessment of rejection will likely increase with time. Computed tomography is most valuable in identifying large parenchymal abnormalities and abdominal fluid. Both US and CT can be used to guide diagnostic and therapeutic percutaneous procedures in hepatic transplant recipients.

Biliary Tract Diseases↗
PubMed1986

Hydrophilic-lipophilic balance as predictor of mucus coating with barium sulfate.

In order to improve barium coating of the mucus layer covering the alimentary tract, various surface active substances are added to commercially available contrast media. The action of additives can be expressed in part by their hydrophilic-lipophilic balance (HLB). In an experimental study using human colonic mucus and barium sulfate USP, surfactants of varying HLB (range, 3-11) were used to study the range of HLB resulting in optimal coating. The best coating occurred with an HLB of 7. Quality of coating may be predicted based on knowledge of the HLB of various surface active additives.

Barium Sulfate↗
PubMed1986

The preliminary evaluation of Mn DTPA as a potential contrast agent for nuclear magnetic resonance imaging.

The pharmacokinetics of 54Mn administered as Mn-diethylenetriamine pentaacetic acid (DTPA) are being investigated to determine if tissue-specific uptake of manganese could be observed while increasing urinary excretion. This chelation and increased excretion should reduce toxicity. In order to obviate the need for repetitive quantitative nuclear magnetic resonance imaging (NMR) we have substituted tracer amounts of a radioisotope of manganese, Mn-54, for the stable ion. By 6 hours, 58 +/- 7% of the injected dose had been excreted in the urine. Peak liver accumulation occurred within 30 minutes (0.50 +/- 0.14% injected dose/g X kg body weight). The pancreas also showed a relatively high accumulation of tracer (0.25 +/- 0.04%/g X kg body weight), reaching a peak at 4 hours. The pancreas to liver ratios were highest at 6 hours (0.7). There was also a substantial accumulation of the manganese in bile. The blood concentration fell very rapidly with little tracer remaining in the blood at 1 hour. Based on these pharmacokinetics, imaging experiments were conducted before, immediately after, and 9 or 24 hours postinjection. These images showed enhanced kidneys and, later (at 9 hours), an excellent parenchymal-collecting system differentiation. The gallbladder was negatively enhanced. The liver showed either increased or decreased signal strength relative to skeletal muscle depending on the pulse sequence used. We conclude that Mn++, administered as Mn-DTPA, merits further investigation as an NMR contrast agent.

Animals↗
PubMed1985

Catheter drainage of the left posterior subphrenic space: a reliable percutaneous approach.

Catheter drainage of left posterior subphrenic collections can be difficult because of lack of a safe access route. We have found that manual compression of the soft tissues of the posterior left flank can create a safe route for catheter drainage, which otherwise would not be possible. This report describes the technique we have used successfully in 8 cases.

Catheterization↗
PubMed1985

Significance of balloon pressure recording during angioplasty. An experimental study.

During angioplasty of artificial stenoses, atherosclerotic human cadaver arteries, and normal canine arteries, pressure and volume of the dilatation balloons were continuously recorded. We found that a sudden yield of a lesion corresponded to a sudden drop in the pressure curve and an increase of the balloon volume. Volume monitoring was insensitive, but pressure recording was very precise. Continuous pressure recording, using a non-compliant inflation system, correctly demonstrated small breaks and ruptures of atherosclerotic vessels, changes not seen on fluoroscopy.

Angioplasty, Balloon↗
PubMed1985

CT of pancreas transplantation.

Thirty-eight abdominal CT examinations obtained on 20 patients after pancreas transplantation were reviewed to determine the CT findings associated with pancreas transplantation and to assess the clinical utility of CT in this setting. Visualization of the transplanted pancreas was variable and was strongly influenced by adequacy of gastrointestinal opacification with contrast material. In four cases, linear high-density material was present within the graft, which, depending upon the surgical technique for handling exocrine secretions, represented either pancreaticojejunal stents or silicone within the pancreatic duct. Abdominal fluid collections were identified in 19 patients and were the most common complication identified by CT. Four of these collections were drained percutaneously. The major value of CT in pancreas transplantation is the identification and management of abdominal fluid collections in patients with abdominal pain and fever.

Abscess↗