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In rat the uptake of colloids by the femur and tibia is dependent on bone plasma flow even if other factors modulate the relationship. We warn Nuclear Medicine scientists against the use of colloid uptake measurement as a marker of the bone macrophagic population, especially in situations associated with modified bone plasma flow.
A new method for the sequential monitoring of skeletal uptake of 99mTc-diphosphonate over a 5-day period, utilising both a gamma camera and whole-body monitor, is presented. It has been found that diphosphonate continues to be removed from bone over this period. Normal subjects appear to lose skeletal activity initially at a more rapid rate than those with altered skeletal metabolism and it is suggested that differences in binding characteristics may exist.
Autoradiography of smears and frozen sections of labelled cell suspensions was used to study the distribution of radioactivity in and among blood cells labelled in either whole blood or leucocyte-rich plasma (LRP) with technetium-99m-SnF2 colloid. The tracer proved selective for neutrophils: the labelling probability (relative to that for erythrocytes) for each cell type in LRP (mean of five samples) was: neutrophils, 9.4; lymphocytes, 3.7; monocytes, 3.0; eosinophils 1.4; erythrocytes, 1.0. When labelling was carried out in whole blood (five samples), 74.5% +/- 8.3% of the cell-bound radioactivity was bound to erythrocytes, 13.6% +/- 6.5% to neutrophils, and 11.9% +/- 2.1% to lymphocytes, whereas in LRP (in which the leucocytes were only slightly outnumbered by erythrocytes), 76.5% +/- 14.9% of radioactivity was neutrophil bound. Labelled cells in smear autoradiographs exhibited two distinct silver grain patterns, "diffuse", consistent with an intracellular radioactive particle (in neutrophils), and "focal", consistent with a cell surface-adhering particle in direct contact with the emulsion (in other leucocyte types and erythrocytes). The phagocytic inhibitor cytochalasin B neither reduced the proportion of labelled neutrophils nor altered the labelling pattern. Neutrophils were able to scavenge radioactivity from the surface of erythrocytes. It is concluded that neutrophils bind 99mTc-SnF2 intracellularly by phagocytosis, with high affinity; other cells become labelled at the cell surface reversibly and with lower affinity. This selectivity is high enough to permit predominantly leucocyte labelling in LRP but not in whole blood.
To study the potential usefulness of 99mTc-methoxy isobutyl isonitrile (99mTc-MIBI) as a substitute for 201Tl in assessing patients with ischaemic heart disease, 24 patients underwent 1 day rest and exercise 99mTc-MIBI single photon emission computerised tomography (SPECT) 1 week after SPECT exercise 201Tl. All patients were catheterized within 1 month after myocardial imaging. In 17 patients, resting first pass radionuclide angiography (FPRNA) was performed with 99mTc-MIBI. The heart to lung ratio for 99mTc-MIBI and 201Tl was calculated both at rest and exercise. The segmental analysis for myocardial perfusion reveals that 87/96 segments (91%) were correctly classified by SPECT 201Tl and 84/96 segments (88%) were correctly classified by 99mTc-MIBI. A significant correlation was present between LVEF measured by 99mTc-MIBI FPRNA and contrast ventriculography (r = 0.85, P less than 0.0001). The heart to lung ratio both at rest and exercise for 99mTc-MIBI is significantly higher than 201Tl (P less than 0.01 and less than 0.001 respectively). We conclude that 99mTc-MIBI is a promising agent for simultaneous evaluation of myocardial perfusion and cardiac function.
A comparative study of the renal uptake rate of 99mTc-dimercaptosuccinic acid (DMSA) was performed using a phantom study and clinical data from 100 patients (200 kidneys) with a variety of renal diseases. The measurement methods for renal uptake rate studied here include a posterior-view method, a conjugate-view method, and a method using single photon emission computed tomography (SPECT). The renal uptake rates obtained by the posterior-view method significantly (P less than 0.001) depended on kidney depth correction. With the SPECT method, the cut-off level for delineating the kidney was changed according to the background count ratio using the results of the phantom study. The renal uptake rates obtained by the SPECT method correlated significantly (P less than 0.001) with those obtained by other methods, and there were no significant differences as compared with those obtained by the conjugate-view method. An analysis of error with the above methods indicated that the error relating to the sensitivity to body thickness was smallest for the SPECT method and greatest for the posterior-view method. In terms of measurement of renal uptake rate only, the conjugate-view method is considered the most useful because it needs no kidney depth correction and requires very little additional effort or examination time.
Soft-tissue vascular anomalies such as haemangioma and vascular malformation are treated by surgical resection, arterial embolization or sclerotherapy. Because the effect of sclerotherapy, i.e. the percutaneous injection of sclerosing agents, depends on intralesional haemodynamics, estimation of flow characteristics of soft-tissue vascular anomalies is essential when determining appropriate patient management. However, lesions are at present divided into only two groups: high flow and low flow. We have developed a new method, direct puncture scintigraphy, to evaluate in detail the haemodynamics of vascular anomalies under conditions simulating sclerotherapy. Twenty-six soft-tissue vascular anomalies in 21 patients were studied. After 30 MBq of technetium-99m Sn colloid was injected percutaneously into the intravascular space of the lesion, dynamic imaging was performed for 5 min. A time-activity curve for the lesion was generated, with the infiltrated activity on injection subtracted. A monoexponential curve was fitted to the declining phase of the time-activity curve, and mean vascular transit time (MTT) was obtained. The lesions were classified into high-flow and low-flow lesions based on radionuclide angiography with intravenous injection of 99mTc-labelled red blood cells, and estimates of MTT in the two groups were compared. The imaging procedures were carried out with no major complications, and broad intralesional diffusion of 99mTc-Sn colloid was achieved in most lesions. The high-flow lesions (six lesions) had a short MTT, ranging from 1.6 to 3.4 s, while the low-flow lesions (20 lesions) had a longer MTT, with no overlap between the groups. MTT showed a wide range in low-flow lesions: it was less than 30 s in six lesions and more than 10 min in five other lesions. Direct puncture scintigraphy provides a quantitative indicator of the flow characteristics of soft-tissue vascular anomalies, and may aid in determining treatment strategies for patients with vascular anomalies.
Glomerular filtration rate (GFR) and renal uptake of dimercaptosuccinic acid (DMSA) were measured in 31 patients with progressive chronic nephropathy before and immediately after the start of treatment with angiotensin converting enzyme (ACE) inhibitor in order to control adverse effects on kidney function. Scintigrams of the kidneys showed an unaltered distribution of DMSA during treatment. GFR estimated by 51Cr-EDTA plasma clearance fell by 14% (P less than 0.01), but renal uptake of 99mTc-DMSA increased by 10% (P less than 0.01). It is concluded that DMSA in chronic renal failure is mainly taken up by the tubular cells from the peritubular capillaries since the uptake was unaffected by the acute decrease in GFR.
In a series of 31 duodenal ulcer patients (23 males and 8 females), who underwent a highly selective vagotomy, gastric emptying characteristics of a solid meal, labeled with [99mTc]stannous colloid, were assessed before, two weeks and six months after operation. The clinical diagnosis was confirmed by endoscopy and x-ray; failure of treatment with H2 antagonists or antacids during 1-18 (mean 5) years was the direct indication for operative treatment. A temporary delay in gastric emptying is noted two weeks after operation (T1/2: 124 vs 57 min). After six months, gastric emptying time has practically normalized. It appears that this is the result of the preservation of the antropyloric vagal nerve supply. In these patients, a 10% recurrence rate is noted, comparable to the results in the literature. Highly selective vagotomy proves to be a safe and effective procedure with few side effects. It does not impair gastric motility.
A pharmacokinetic model was developed for the renal imaging agent 99mTc-DMSA in anesthetized rats, which incorporated data from serial measurements of blood and urine simultaneously with dynamic images obtained over an 8-h period. Animals which received a 10 mg/kg dose of unlabeled DMSA immediately before 99mTc-DMSA injection had a significantly reduced kidney accumulation and greater urinary elimination of 99mTc than animals which received the radiopharmaceutical alone. The kidney clearance was also significantly lower in rats receiving unlabeled DMSA, but no significant difference was determined between the urine clearance estimates of the two animal groups. Because the increase in the amount eliminated in the urine was not coupled with a significant change in urine clearance, it would appear that unlabeled DMSA saturated the kidney uptake mechanism(s) of 99mTc-DMSA without modifying the urinary clearance process. This interpretation is consistent with the hypothesis that renal handling of 99mTc-DMSA is governed by both glomerular filtration and peritubular capillary uptake. The simultaneous acquisition of blood, urine and non invasive image data allows for a comprehensive and informative model of the physiological disposition of 99mTc-DMSA.
The authors report 14 lymphoscintigraphies of the ovary, 8 before and 6 after the menopause. Injection of colloid labeled with technetium 99 m with elective lymphatic absorption was made into the mesovarium under laparoscopic control. Frontal and lateral images of the lymphatic drainage were made with a gamma camera 4-6 h after injection. Even in this short preliminary series, the premenopausal women showed major local and regional lymphatic circulation with drainage to the lumbo-aortic and pelvic nodes. After the menopause the lymphatic flow decreased and drainage was essentially by the aorto-lumbar nodes.
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A patient is described with a rapidly progressive Kaposi's sarcoma following immunosuppressive therapy with fludarabine monophosphate (FAMP) for chronic lymphocytic leukemia. The development of this tumor was accompanied by progressive thrombocytopenia, due to trapping of the platelets in the Kaposi sarcoma, without signs of consumptive coagulopathy or microangiopathic hemolytic anemia. This sequestration process might be caused by the abnormal structure of the tumoral vessels, leading to exposure of subendothelial structures like collagen, von Willebrand's factor, and tenascin to the vessel lumen. A severe immunosuppression due to the lymphocytotoxic effect of FAMP on several T-cell subpopulations was seen. This case confirms the importance of immunosuppression as a co-factor in the development of Kaposi's sarcoma also in HIV-negative patients, and adds Kaposi's sarcoma to the differential diagnosis of thrombocytopenia in immunosuppressed patients.
OBJECTIVE: Determine the evolution of left ventricular ejection fraction during weaning. DESIGN: Prospective study. SETTING: Intensive care unit of a university teaching hospital. PATIENTS AND PARTICIPANTS: 12 consecutive mechanically ventilated patients, without documented coronary artery disease, suffering from acute exacerbation of chronic obstructive pulmonary disease and able to be weaned. MEASUREMENTS AND RESULTS: Left ventricular ejection fraction was determined during mechanical ventilation, inspiratory pressure support (10 cmH2O) and spontaneous ventilation with constant inspiratory oxygen fraction using technetium 99m radionuclide angiography. Spontaneous ventilation induced a significant decrease in left ventricular ejection fraction from 54.5 +/- 12.4 to 47.0 +/- 13% (p < 0.01). Inspiratory pressure support induced a slight but non-significant decrease in left ventricular ejection fraction from 55.0 +/- 12.1 to 50.3 +/- 12.4%. Left ventricular ejection fraction was homogeneously reduced by spontaneous ventilation without patent regional wall motion abnormalities of the left ventricle. Myocardial 201thallium imaging performed 15 min after weaning showed a normal perfusion in the left ventricle anterior and posterior free wall. CONCLUSION: Weaning of patients suffering from chronic obstructive pulmonary disease without coronary artery disease induced a significant reduction in left ventricular ejection fraction. The non significant decrease in left ventricular ejection fraction observed with inspiratory pressure support suggested that our results might be explained by a weaning induced increase in afterload.
We hereby describe a patient with amyloidosis complicated by reversible functional asplenia and spontaneous rupture of the liver with subcapsular hematoma which resolved completely with conservative therapy. These two rare findings may result from extensive vascular amyloid in this patient.
A study was made of 26 patients diagnosed as phase I reflex sympathetic dystrophy. In all of them, a bone:soft tissue uptake index was quantified by scintigraphic scanning before treatment and 3 months later. Eighteen patients were treated with 100 MRC units salmon calcitonin, followed by 500 mg elemental calcium 4 hours after hormone administration. The treatment was administered 10 days a month separated by intervals free of therapy. The other 8 patients were treated without interruption with 500 mg naproxen every 12 hours. In the group treated with calcitonin and calcium, the uptake index declined from 13.3 +/- 8.2 to 4.1 +/- 1.8 (p less than 0.001). The uptake index rose from 2.1.3 +/- 17.7 to 31.1 +/- 23.0 (NS) in the naproxen group. Using the Student t-test for paired samples to evaluate individual changes, a highly significant difference was reached (p less than 0.005) in the calcitonin-calcium group. The difference was also significant (p less than 0.01) in the naproxen group, but it was negative (t = 3.620). These results confirm the efficacy of treating reflex sympathetic dystrophy with calcitonin and calcium and the superiority of this treatment as compared with nonsteroidal anti-inflammatory drugs.
BACKGROUND: Preoperative cutaneous lymphoscintigraphy (LS) to identify sentinel (first-tier) lymph nodes was performed in 250 consecutive melanoma patients before wide local excision only or wide local excision with sentinel node biopsy. METHODS: The location of the sentinel nodes was marked on the overlying skin in all patients. Whether or not tracer was present in second-tier lymph nodes on the delayed scans was recorded for each patient and related to the lesion site at which the tracer had initially been injected. For 100 consecutive patients the rate of tracer movement through the lymphatic channels was compared to the incidence of second-tier drainage. RESULTS: Second-tier nodes were visualized in all patients with melanomas on the leg and thigh, and in almost all patients with melanomas on the forearm and hand, but were seen less often in patients with more centrally located melanomas. There was a significant correlation between the rate of lymph flow and the incidence of demonstrable second-tier drainage. CONCLUSION: The results suggest that the physiology of the lymphatic system varies depending on the origin of the lymphatic vessel. These findings have important implications for application of the sentinel node biopsy technique in individual patients.
The bone-seeking agent 99mTc-labeled 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) unexpectedly binds to particles of human articular cartilage as well as cortical bone in vitro. Collagen also sequesters this compound, suggesting that collagen contributes to the uptake of 99mTc-HEDP by cartilage and bone. Particles of the bone mineral calcium hydroxyapatite also bind 99mTc-HEDP in vitro. Pretreatment of particles with Er3+ stimulates binding in each case. Lowering the pH of incubation to pH 2 has this effect for bone, cartilage, and collagen, but not for calcium hydroxyapatite. Mechanisms additional to the simple ionic attraction between the phosphonate groups of HEDP and metal cations such as Ca2+ are responsible for the uptake of 99mTc-HEDP by body tissues.
We have recently found that antimony (originating from the technetium 99m antimony trisulfide colloid, used for preoperative lymphoscintigraphy) can be measured in tissue sections from archival paraffin blocks of sentinel nodes (SNs) by means of inductively coupled plasma mass spectrometry (ICP-MS) to confirm that removed nodes are true SNs. We performed a retrospective analysis of antimony concentrations in all our false-negative (FN) SNs to determine whether errors in lymphadenectomy (i.e., failure to remove true SNs) may be a cause of FN SN biopsies (SNBs). Among 27 patients with an FN SNB, metastases were found on histopathologic review of the original slides or additional sections in 7 of 23 patients for which they were available; however, antimony concentrations were low in 5 of 20 presumptive SNs. Our results suggest that an FN SNB can occur because of failure to remove the true SN as well as histopathologic misdiagnosis.