Biomedical subjects
Publications and source records attributed to R F Uren.
A 3.5-yr-old child presented with a large thoracic mass which showed avid accumulation of 67Ga and 201Tl was studied. Histology showed a peripheral neuroectodermal tumor of the chest wall typical of the malignancy described as the Askin tumor. The 201Tl studies were a more accurate method of following tumor response to therapy than 67Ga scintigraphy.
Lymphoscintigraphy (LS) has been performed for 8 years in patients of the Sydney Melanoma Unit, to define lymphatic drainage patterns. Over the past 2 years, LS has also been used to locate the sentinel lymph node prior to surgery. Our technique for LS and subsequent sentinel node biopsy has an accuracy of 97%. All sentinel nodes must be marked to ensure the successful application of the sentinel biopsy technique. We have found that the axilla and groin average just over one sentinel node per draining node group for lesions on the trunk and upper limb, but have noted that drainage to the groin differed when lower limb lesions were studied. Because of the anastomosis of lymph vessels in the upper thigh, multiple sentinel nodes are identified in the groin in some patients. We have found an average of three sentinel nodes in the groin when lymph drainage from lower limb lesions was studied with LS. This difference demands a modification of the LS technique, with early imaging of the groin nodes to identify all sentinel nodes in each patient. The depth of the sentinel nodes can also be measured and the location of all interval nodes marked on the skin. This ensures that all sentinel nodes and interval nodes can be removed at the time of surgery.
Thirty-five children (aged 0-9 yr) who had presented with Stage IV neuroblastoma were studied to see if avidity for 67Ga or 99mTc-methylene diphosphonate (MDP) uptake in both primary and secondary sites at diagnosis conferred any prognostic significance. Twenty-three percent of the patients were disease free and off treatment at the time of study. Crude survival did not differ between groups. Duration of survival and the likelihood of completing treatment were related to the scintigraphic appearance at the time of diagnosis, after adjustment for potential confounding effects, using Cox's proportional hazards regression and multiple logistic regression. After adjustment for confounding influences, neither 67Ga avidity nor uptake of 99mTc-MDP was associated with a significantly worse prognosis, both in terms of adjusted survival and likelihood of completing treatment. Patients with 67Ga-avid scans at diagnosis did not demonstrate significantly worse survival (HR 1.47, 95% CI 0.43-5.11) than those without 67Ga avidity. They were somewhat less likely to complete treatment (OR 0.23, 95% CI 0.03-1.63), but this did not reach statistical significance. Similarly, although patients with 99mTc-MDP positive scans demonstrated somewhat worse survival (HR 2.47, 95% CI 0.45-13.54), this result did not reach statistical significance, nor were they less likely to complete treatment (OR 0.69, 95% CI 0.07-6.67) than those with 99mTc-MDP negative scans. Uptake of 99mTc-MDP into extraosseous sites was also not associated with worse survival (HR 1.45, 95% CI 0.58-3.62) nor with decreased likelihood of completing treatment (OR 0.78, 95% CI 0.12-5.09). Other than indicating disease stage, these results do not support the hypothesis that the scintigraphic appearance at diagnosis confers prognostic information in children with advanced neuroblastoma.
Lymphoscintigraphy was performed in 209 patients with high-risk melanoma of the trunk referred to the Sydney Melanoma Unit and considered for lymph node dissection. Lymphoscintigraphy accurately defined the draining lymph node groups and was 94% sensitive in detecting draining sites that contained metastases. When combined with the clinical finding of palpable lymph nodes, the sensitivity rose to 98%. Most patients showed lymph drainage to one or two node groups and only 22 patients showed drainage to 3 or more node groups. The major lymph channels could also be marked on the skin prior to incontinuity dissection. Most patients had multiple draining lymph channels and these often diverged significantly from each other in the path to the draining node group. The number and location of interval nodes could be determined and marked on the skin. These and the major lymph channels could thus be excised at the time of surgery. Unusual drainage patterns were sometimes seen; for example, three patients displayed a new lymph pathway with direct drainage from the back anteriorly to the para-aortic nodes. The location of the sentinel nodes in each draining lymph-node group could also be marked on the skin prior to surgery, enabling quick and accurate identification of this node, using the blue-dye technique if biopsy were to be performed. These findings lead us to recommend lymphoscintigraphy prior to wide local excision in patients with truncal melanoma who are candidates for surgery. Lymphoscintigraphy results will help plan surgery and lead to minimum surgical intervention, consistent with effective surgical management.
The authors describe the scintigraphic findings of bone and Ga-67 imaging performed on three patients thought to have Pott's puffy tumor. Two patients did indeed have it, but the third patient's "puffy tumor" was a soft tissue abscess.
The "cold hip" sign on bone scan is often seen in patients referred with irritable hip. This sign is due to fluid in the hip joint under pressure causing impaired perfusion of the structures within the joint capsule. In a retrospective review, 22% of patients with this sign on bone scan were found to have septic arthritis at surgery. This fact would appear to justify surgical drainage or aspiration of any hip showing this sign on scan. An attempted follow-up study through the medical records was incomplete because of the short follow-up on most patients. The possibility that temporary impairment of blood supply to the head of the femur causes long-term damage to the hip is unanswered on this study, and a long-term recall follow-up study is underway.
The relationship between radionuclide and thermodilution measurement of stroke volumes (SV) was investigated in 30 patients without valvular regurgitation or intracardiac shunt (group A) at rest and during exercise. Both attenuated radionuclide right ventricular (RV) and left ventricular (LV) SV measurements correlated well with the SV determined by the thermodilution method (r = 0.87 and r = 0.93, all P less than 0.001). The reliability of the radionuclide method to estimate SV was evaluated prospectively in two additional groups of patients. In 11 patients without valvular regurgitation or intracardiac shunt (group B) the radionuclide RVSV and LVSV closely approximated to thermodilution SV at rest and during exercise. In 15 patients with aortic regurgitation (group C) the radionuclide stroke volume ratio correlated well with the angiographic regurgitant fraction. Thus, both RVSV and LVSV and the severity of aortic regurgitation can be reliably measured with gated radionuclide ventriculography.
To examine the effects of nifedipine on the left ventricular (LV) functional response to isometric exercise in patients with aortic regurgitation (AR), 20 patients with isolated, moderate to severe AR performed 3 minutes of handgrip exercise at 33% of their maximal voluntary contraction, before and after administration of 20 mg of sublingual nifedipine. Although handgrip exercise produced similar increases in heart rate and systolic blood pressure before and after nifedipine treatment, heart rate was higher and systolic blood pressure lower with handgrip exercise during nifedipine treatment. LV end-diastolic volume index was not different during the control period and nifedipine handgrip exercise, but the increase in end-systolic volume index was smaller and the ejection fraction was higher during nifedipine handgrip exercise. Nifedipine reduces afterload and ameliorates handgrip exercise-induced LV dysfunction in patients with AR.
This study was undertaken to assess the role of gallium-67 studies in the management of malignant melanoma. Gallium-67 studies were performed in 41 patients prospectively to determine the presence of regional lymph-node spread or distant metastatic disease. A high correlation was found in the assessment of lymph-node status between the results of the gallium-67 study and those of the histological examination. Distant metastases were demonstrated in brain, lung, bone, and liver. In three patients, lymphoscintigraphy was performed before the gallium-67 study in order to assess regional drainage; this may prove to be a very useful combination in determining treatment strategy, especially in patients with truncal melanoma.
Hepatic haemangioma is the most common vascular abnormality of the liver occurring in 0.4% to 7% of reported autopsy series. Its diagnosis is critical, as biopsy of these lesions can lead to catastrophic results owing to uncontrolled haemorrhage. Hepatic angiography is normally used for diagnosis. Previous reports of attempts to confirm the diagnosis by non-invasive means such as ultrasound and computed tomography (CT) have shown these tests to be non-specific. The usefulness of the patient's own red blood cells labelled with technetium-99m (99mTc RBC) in the non-invasive diagnosis of hepatic haemangioma was investigated. After the intravenous injection of the isotope, flow, early static, and delayed static views were obtained. A flow study demonstrating decreased perfusion and a late blood-pool study showing local blood volume markedly greater than that of the normal liver were characteristic of haemangioma. 99mTc RBC studies are useful in the evaluation of focal defects in the liver when cavernous haemangioma is suspected. A diagnostic pattern is present in patients with cavernous haemangioma.
The Budd-Chiari syndrome is an uncommon clinical entity, in which invasive investigations are necessary to make a definitive diagnosis. Liver scintigraphy is a simple, safe, non-invasive screening test that can be performed when this diagnosis is suspected. If the appearance on the liver scan supports the diagnosis, further, more definitive, procedures can be undertaken. Four cases are reported to illustrate the role of liver scans in this condition. A case of superior vena caval obstruction which was diagnosed on a liver scan is also presented for comparison.
The acute effects of nifedipine (20 mg sublingually) on hemodynamics and cardiac function were studied at rest and during supine bicycle exercise in 20 patients with aortic regurgitation. At rest, heart rate increased by 13%, systemic vascular resistance decreased by 34% and regurgitant index decreased by 17%. The change in systemic vascular resistance was related to its initial rest level (r = 0.82, p less than 0.001) and to the changes in forward cardiac output (r = 0.58, p less than 0.01) and regurgitant index (r = 0.60, p less than 0.01). Left ventricular end-diastolic and end-systolic volumes, stroke volume and ejection fraction were unchanged, whereas right ventricular ejection fraction increased. During exercise, nifedipine administration further increased heart rate by 8% and decreased systemic vascular resistance by 19%. Both forward stroke volume and forward cardiac output increased, but total left ventricular stroke volume was unchanged, resulting in a significant decrease in regurgitant index. Although left ventricular end-diastolic volume was slightly decreased, end-systolic volume did not increase; thus, ejection fraction was higher than that during control exercise (p less than 0.01). Right ventricular ejection fraction increased further. In aortic regurgitation, the acute administration of nifedipine improved cardiac performance and reduced regurgitation at rest and during exercise as a result of afterload reduction and increased heart rate. Whether these beneficial effects will occur during long-term therapy requires further investigation.
A case of focal defects seen on liver scintigraphy on the basis of right ventricular failure is presented. The pattern bore a striking similarity to that seen in hepatic metastases.
Radionuclide plethysmography (RPG) is a new technique that uses Tc-99m labelled red blood cells to ascertain changes in venous volumes by detecting the change in counts in response to the inflation and deflation of proximal thigh cuffs. Diagnosis of ileofemoral venous occlusion is possible using this technique, which also provides kinetic data of venous outflow. A range of normal values was defined in 19 subjects for per cent change in venous capacitance and venous outflow. Twenty-one patients with suspected deep venous thrombosis were studied prospectively using RPG, radionuclide venography (RV), and contrast venography (CV) to establish the usefulness of RPG alone and in combination with RV in the diagnosis of deep venous thrombosis. RPG proved to be a reliable technique for the diagnosis of ileofemoral venous thrombosis (sensitivity, 91%; specificity, 100%). RV was less sensitive (73%) and less specific (93%) in diagnosing that condition. When RPG is used as the criterion for the detection of ileofemoral vein thrombosis and RV is used as the criterion for the detection of calf vein thrombosis, the combined techniques show improved sensitivity (92%) and specificity (93%) for the detection of all deep venous thromboses.
The recent development of single-photon emitting radiopharmaceuticals that reflect cerebral blood flow has introduced a new era for the useful application of nuclear medicine to the investigation of neurological disease. Using 123I labelled N-isopropyl-p-iodoamphetamine, we have performed emission-computed tomographic scans of the brain in several clinical settings. These studies display cross-sectional maps of cerebral blood flow and promise significant clinical utility in a variety of brain diseases. In the eight patients with epilepsy, the scans showed good localization of the abnormal foci, and correlated well with the findings at operation in the five patients who were submitted to surgery. All 10 patients with stroke had abnormal scans, and the abnormalities in cerebral blood flow were frequently more extensive than the lesions seen on the transmission-computed tomographic scan. This initial experience leads us to anticipate an increasing role in clinical neurology for single-photon emission computed tomographic scans of cerebral blood flow.
Bleeding from angiodysplasia of the gastrointestinal tract has become widely recognized. In most patients there is a single focal lesion in the colon. Small bowel involvement is rare and usually associated with colonic lesions. There have been no reports of bleeding angiodysplasia affecting the small bowel only. We were able to detect bleeding from an isolated angiodysplasia of the jejunum and correctly localize it. Our diagnosis was greatly aided by the use of dynamic data collection and by the cinematic display of the data.
An all-digital nuclear medicine department is described. Nuclear medicine images are acquired by a separate computer interfaced to each camera. The digital images are viewed, manipulated, and interpreted from remote display stations in an interpretation area. The interpretation is dictated into a Rapid Telephone Access System (RTAS), where the voice is digitized and stored. By dialing the patient's identification number, the referring physician can hear the interpretation over any telephone. The images are filed on large storage discs. The digital scans can be rapidly and easily accessed for later review by the use of several directory programs. This system has brought not only efficiency and cost savings, but the ability for remote viewing elsewhere in the hospital and telephone transmission of nuclear cardiology studies from community hospitals for interpretation in the digital nuclear medicine department.
Data of nuclear cardiology studies are acquired on a computer and transmitted by telephone from a community hospital to a computer at a teaching hospital for analysis. Interpretations of the studies are dictated into a RTAS radiology reporting system. The referring physician and transcriptionists from the sending hospital may hear the interpretations by calling into RTAS on the same day as the studies were performed.