Comparison of independent aura, ictal and interictal cerebral perfusion.

Technetium-HMPAO cerebral SPECT was performed interictally, immediately after an independent aura and ictally in a patient with complex partial seizures. Interictally there was a left inferior frontoparietal region of decreased perfusion. Ictally there were a number of foci of increased perfusion. The aura study showed focal hyperperfusion in the left frontal region and decreased perfusion in the adjacent cortex posteriorly, suggesting a zone of suppression. This may be the cause or effect of the nonprogression of the aura. The case raises the possibility that cerebral perfusion studies performed immediately after independent auras may localize seizure foci if ictal studies are nonfocal.

An unusual cutaneous lymphoma with B and T cell characteristics showing gallium-67 positive benign thymic hyperplasia following intensive chemotherapy.

This case illustrates two interesting features. Firstly it describes an unusual cutaneous lymphoma in an adolescent girl. This lymphoma showed features of B and T cell lineages with rearrangements of both immunoglobulin heavy chain and T cell beta chain genes. Secondly it describes the development of gallium-67 citrate (67Ga) scan positive benign thymic hyperplasia, 15 months after diagnosis and three months after cessation of intensive chemotherapy.

Tc-99m white cell scintigraphy in suspected acute infection.

The usefulness of In-111 labeled white cells in acute infection is well documented but the role of Tc-99m labeled white cell scintigraphy (WCS) has not been as clearly established. Using stannous fluoride colloid and a simple labelling procedure with 20 ml of autologous whole blood, three cases are presented in which Tc-99m WCS established unexpected diagnoses in patients who had remained undiagnosed despite extensive investigation.

Current role of gallium scanning in the management of lymphoma.

Gallium 67 scanning in the malignant lymphomas has been done, with variable success, for over 20 years. After initial enthusiasm, the technique fell into disrepute and it was not until the early 1980s that it enjoyed a revival. There have been many major contributions to the literature, both favourable and unfavourable. The reasons for the latter include: poor instrumentation (only single-pulse height analysis), low gallium 67 doses, impatient and careless scanning techniques, timing of the study after treatment (chemotherapy, radiation) and insensitive methods of confirmation of the presence or absence of disease ("truth"). Anatomical diagnostic techniques (computed tomography, plain X-radiography, magnetic resonance imaging and others) are incapable of distinguishing viable tumour in normal-size lymph nodes or necrotic/fibrotic residual masses. With improvements in instrumentation (triple-pulse height analysis, gamma camera resolution and tomographic techniques) gallium 67 can detect active tumour in residual masses and in normal-size nodes. This is due to gallium 67's unique ability to localize in viable tumour cells. It has greater than 90% sensitivity, specificity, accuracy and positive predictive value in patients with lymphoma. Its major contributions are in: staging (changing management of mediastinal disease, obviating the need for a laparotomy and clearly identifying stage IV disease); detecting relapse or residual, progressive disease (it establishes true complete remission and is often the first and only evidence of relapse before clinical evidence); predicting response to therapy (failure to convert to a negative scan post-treatment signals a poor prognosis and alternative therapy is required); and predicting outcome--prognosis (it is the only diagnostic modality to predict outcome accurately).

Gallium scanning in the management of mediastinal Hodgkin's disease.

Gallium-67 scanning was performed pre- and post-therapy in 25 patients with Hodgkin's disease and a mediastinal mass. At restaging after therapy, radiographs (or CT scans) did not predict the presence of active disease whereas gallium scans did with a high degree of accuracy. Gallium-67 determined disease activity in those patients who had a residual mediastinal mass predicting outcome in 11 out of 12 patients; one had a late relapse at 7 years. In patients without a residual mass gallium scanning was again accurate, predicting outcome in 11 of 13 patients. Two patients with negative gallium scans but subsequent active disease were scanned too soon after chemotherapy. The results suggest that gallium scanning has an important role in the management of mediastinal Hodgkin's disease and is superior to all current methods of assessing disease activity irrespective of the presence of a residual mediastinal mass.

Normalised radionuclide measures of left ventricular diastolic function.

Abnormal left ventricular diastolic function is being increasingly recognised in patients with clinical heart failure and normal systolic function. A simple routine radionuclide measure of diastolic function would therefore be useful. To establish this, the relationship of peak diastolic filling rate (normalized for either end diastolic volume, stroke volume, or peak systolic emptying rate), and heart rate, age, and left ventricular ejection fraction was studied in 64 subjects with normal cardiovascular systems using routine gated heart pool studies. The peak filling rate, when normalized to end diastolic volume, correlated significantly with heart rate, age and left ventricular ejection fraction, whereas normalization to stroke volume correlated significantly to heart rate and age but not to left ventricular ejection fraction. Peak filling rate normalized for peak systolic emptying rate correlated with age only. Multiple regression equations were determined for each of the normalized peak filling rates in order to establish normal ranges for each parameter. When using peak filling rate normalized for end diastolic volume or stroke volume, appropriate allowance must be made for heart rate, age and ejection fraction. Peak filling rate normalized to peak ejection rate is a heart rate independent parameter which allows the performance of the patient's ventricle in diastole to be compared with its systolic function. It may be used in patients with normal systolic function to serially follow diastolic function or if age corrected, to screen for diastolic dysfunction.

The role of nuclear medicine in liver transplantation.

The role of hepatobiliary isotopic scanning after liver transplantation was assessed in the first 12 adult patients in the Pilot National Liver Transplantation Programme who underwent this procedure at the Royal Prince Alfred Hospital. Iminodiacetic-acid derivative (HIDA) studies were useful in the non-invasive assessment of hepatic function and biliary excretion. The following four clinical situations were assessed by hepatobiliary scans: early graft function; rejection episodes; vascular complications; and biliary-tract problems. Nuclear medicine has an important and valuable role in the postoperative monitoring of patients after liver transplantation. The studies are non-invasive and can be performed readily at the bedside in the intensive care unit.

SPECT evaluation of arterial perfusion in regional chemotherapy.

Simultaneous emission and transmission tomography was performed after the injection of [99mTc]MAA in 30 patients undergoing intra-arterial chemotherapy to nonhepatic sites to determine the accuracy of catheter placement. The transmission and emission data were reconstructed in transverse, and optionally, coronal and sagittal planes. The correlation of the emission scan with the reconstructed transmission data allowed accurate anatomical localization of the infusate distribution. In seven patients, catheter placement resulted in perfusion to nontumor sites, and hence required repositioning. MAA accumulation was seen in the lungs of all patients, regardless of tumor site, indicating arterio-venous shunting of the MAA. The degree of uptake in the lungs was quantified from planar anterior/posterior thorax images in terms of injected dose in ten patients, with values of 5-50% of injected dose present in the lungs. The technique provides a noninvasive means of accurately determining regional perfusion of chemotherapeutic agents delivered intra-arterially.

Radionuclide cisternography in the diagnosis and management of cerebrospinal fluid leaks: the test of choice.

While leakage of cerebrospinal fluid is an intermittent and usually short-lived phenomenon, it may be fatal. The difficulty of making this diagnosis has led to the adoption of many diagnostic procedures. Fifteen patients have been studied by radionuclide cisternography with the concomitant use of nasal pledgets. Six of the studies showed cerebrospinal fluid leakage; the sensitivity of the technique was 100%. The site of leakage was confirmed surgically in three of the patients. No other technique offers comparable sensitivity with high patient acceptance and low morbidity.

Early supradiaphragmatic Hodgkin's disease. High-dose gallium scanning obviates the need for staging laparotomy.

Experience with 16 sequential patients with Stage IA/IIA supradiaphragmatic Hodgkin's disease who had no evidence of intra-abdominal disease using high-dose gallium and computerized tomography scanning is reported. Subsequent staging laparotomy also was negative in all these patients and did not alter management decisions. It is suggested that high-dose, whole-body gallium scanning and other noninvasive staging procedures give reliable data for therapeutic decisions.

Skin blood flow measurement with xenon-133 to predict healing of lower extremity amputations.

Many techniques have been proposed to help the surgeon select the most distal amputation level that will heal. Skin blood flow measurement with xenon-133 (133Xe) is one of the best documented predictors of amputation healing, but the lowest flow consistent with healing has not been agreed upon. Our early experience with the method is reported. Skin blood flow was measured in 16 patients undergoing 17 lower extremity amputations. Twelve amputations healed (mean skin blood flow 3.69 +/- 2.73 ml/100 g of tissue/min) and five failed (mean skin blood flow 0.80 +/- 0.61 ml/100 g of tissue/min) (P less than 0.05). No amputation healed if the skin blood flow was less than 1.0 ml/100 g of tissue/min. A skin blood flow above 1 ml/100 g of tissue/min, measured with 133Xe, may be a useful guide to the level at which to amputate while minimizing unnecessary proximal amputation, but the method requires further prospective evaluation.

Blood-pool studies of the liver. Diagnostic patterns exist in cavernous haemangioma.

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 role of gallium-67 studies in the management of malignant melanoma.

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.

Radionuclide plethysmography and Tc-99m red blood cell venography in venous thrombosis: comparison with contrast venography.

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.

Cardiac tamponade: accurate diagnosis by radionuclide angiography.

This study was performed to define the signs of cardiac tamponade on radionuclide angiography. The first pass studies were performed on a large field gamma camera, using a bolus of technetium pertechnetate. Three hundred and seventy-two studies were analysed. Cardiac tamponade requiring surgical intervention was present at the time in 28 studies. The diagnostic signs of cardiac tamponade on radionuclide angiography were: (1) Right ventricular compression--sensitivity 82%, specificity 97%, predicitive value of a positive result 72%, predictive value of a negative result 99%, and (2) Right atrial compression--sensitivity 21%, specificity 99%, predictive value of a positive result 75%, predictive value of a negative result 94%. Cardiac tamponade can be accurately diagnosed on radionuclide angiography and thus indicate those pericardial effusions which require urgent drainage.