Biomedical subjects
Publications and source records attributed to P R Koehler.
We studied the subjective rating of MR image quality as field strength, slice thickness, number of acquisitions and matrix size were varied. Matrix and number of acquisitions had the most significant effect on image quality. Therefore, in comparisons of image quality, technique must not be disregarded.
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New CT software programs allow rapid-sequence images to be obtained. During a period of 12 sec, multiple CT images can be produced, so that the progression of contrast flow at intervals of 1 sec or less can be followed. In addition, as many as 16 consecutive 3-sec scans can be performed, or arbitrary time intervals inserted between scans. The rapidity with which the contrast medium enters and leaves a specific tissue may be a valuable, non-invasive diagnostic tool in differentiating enhancing lesions. Other potential applications are mentioned.
The CT appearance of normal retroperitoneal lymph nodes has been described. In many instances the structures are too small to be identified. other retroperitoneal structures, such as collapsed bowel loops, vessels, and other perirenal structures, may simulate the presence of nodes. CT is of great benefit in disease with bulky tumors, such as non-Hodgkin's lymphoma, testicular tumors, etc. Its usefulness is much more limited in disease that may have extensive nodal involvement but no significant enlargement of the nodes. The accuracy of CT scanning in Hodgkin's disease and in many instances of genitourinary tumors is questioned, and we submit that further studies are needed to establish the reliability of this mode of examination.
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An accessory patient table has been built to take better advantage of the 90-cm gantry opening of the Varian whole-body scanner. Coronal and sagittal scans of the head can be made routinely and comfortably.
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Retrospective review of 100 lymphograms showed that routine chest radiography after injection of the lymphographic contrast medium and follow-up films 24-48 hr later yielded no clinically useful information. It was concluded that routine postlymphography chest radiography is not necessary and should be reserved for patients in whom complications are suspected.
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Recent government directives and manufacturers' warnings have strongly cautioned against reuse of angiographic catheters and guide wires following cleaning and sterilization. Though it is theoretically possible that complications might result from reuse, actual documentation is lacking. Complete sterility can be achieved by standard procedures even when the devices are intentionally infected. Survey data indicate no increased incidence of mechanical malfunction when these devices are reused.
In the early 1960's lymphography was received enthusiastically. Expectations were high that a very accurate diagnostic method for the detection of metastases had been found. This enthusiasm subsided after it became apparent that small lesions could not be discerned and that the images demonstrated were frequently nonspecific. Better correlation was achieved with advanced stages of cancer but because the presence of metastases was usually already known, it was questionable if the lymphogram contributed much to the management of the patient. In recent years, after the examination was placed in its proper prospective, the value and status of lymphography in patients with cancer were reassessed. The radiographic findings were divided into direct, or actual demonstration of metastastases, and indirect changes--those changes resulting from replacement of lymph nodes or blockage of the vessels by metastases. Lymphography proved particularly valuable in the diagnosis and staging of patients with pelvic cancer arising from such organs as cervix, uterus, vulva, ovary, and from tumors arising from the prostate, testicles, and penis. It also proved valuable in the assessment of extension of disease in melanomas of the extremities. The value of the positive lymphogram is easy to assess. However, when one encounters a "normal" lymphogram, one must realize that this does not exclude the presence of metastatic disease; it merely demonstrates that the the time of the study no lesions were recognized in visualized lymph nodes. Therefore, the negative lymphogram should not result in any modification of treatment which would have been prescribed under the same clinical circumstances if one did not have the lymphogram at hand.
Two patients with massive gastrointestinal bleeding are reported. One bled from an aneurysm of a branch of the left hepatic artery, the blood reaching the bowel through communication with the biliary tree. The second had an aneurysm of a branch of the splenic artery which communicated with the pancreatic duct. This type of bleeding is intermittent and, consequently, actual extravasation of contrast media is not always seen. Therefore, if one sees an aneurysm of a visceral artery, even if it does not directly supply the enteric tract, one should consider the possibility that it is the origin of the hemorrhage. Pathogenesis, diagnostic modalities, and therapeutic implications are discussed.
Fractionated administration of iopanoic acid (Telepaque) has already been shown to result in superior visualization of the gallbladder. A similar study was undertaken to evaluate the effect of fractionation when iocetamic acid (Cholebrine) is employed. It was found that the gall bladder is opacified better if Cholebrine is given in a single dose.
B-mode ultrasonography has been used in the evaluation of complications following renal transplantations. The main indications for examining the patient are decreased renal function, clinically suspected abscesses, or suggestions of a mass in the region of the transplant. In most patients, worsening renal function is due to rejection. In 10 of 50 patients, however, lesions such as lymphoceles, postoperative hematomas, abscesses, and urine leakage were diagnosed. Ultrasonography proved to be a noninvasive and reliable method for the assessment of these complications.
By employing the three basic diagnostic modalities of uroradiology--intravenous urography, retrograde pyelography, angiography--an accurate radiological diagnosis can be made. Since congenital multicystic disease by definition is a nonfunctioning dysplastic kidney with an atretic or absent ureter and absent renal vasculature, these diagnostic methods are tailored precisely to demonstrate the specific characteristic functional and pathological features of congenital multicystic kidney disease. We find no function on intravenous urography, hypoplastic atretic ureter on retrograde pyelography, and an absent or hypoplastic renal artery indicated on angiography.
A patient with hemorrhage into the pancreatic duct from a splenic artery aneurysm is presented. The angiographic, retrograde pancreatographic, and pathological findings are demonstrated. The diagnosis was established by demonstrating an enlarging aneurysm by serial angiograms. The location of the splenic artery aneurysm was confirmed by retrograde pancreatography before surgery. The distal pancreas containing the aneurysm was resected.
The high incidence of renal mass lesions, particularly the frequent occurrence of renal cysts in elderly patients, makes the differentiation of benign from malignant renal mass lesions an important clinical challenge. Accurate preoperative diagnosis is important for establishing the prognosis and for avoiding unnecessary surgery, with its increased morbidity and expense, when benignity can be established confidently. A broad spectrum of radiographically related imaging and biopsy techniques are currently available for the detection and characterization of renal mass lesions. In addition to plain film findings and radiographic contrast studies, nuclear medicine techniques and ultrasound analysis of renal mass lesions have made significant contribution to accurate differentiation of cysts from solid masses. Ultrasound scanning and cyst puncture in particular have attained critical significance in the workup of renal masses; Several recent publications analyze the accuracy, comparative costs, complications, and cumulative confidence of the various available procedures. An accuracy of 95% or greater appears attainable when definitive interpretation of the appropriate test is technically achieved, The current review will discuss the recent literature concerning renal mass lesions. The techniques and findings which should lead to acceptable confidence in the nonoperative differentiation of renal masses will be discussed. Factors regarding safety, accuracy, and expense will be considered.
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