Limited value of 99mTc depreotide single photon emission CT compared with CT for the evaluation of pulmonary lesions.

OBJECTIVES: A contrast-enhanced multidetector CT (MDCT) scan is the first choice examination when evaluating patients with suspected lung cancer. However, while the clinical focus is on CT, research focus is on molecular biological methods whereby radiolabelled pharmaceuticals are injected into participants and target malignant lung tumours. We examined whether a contrast-enhanced MDCT scan supplied with an additional non-contrast enhanced high-resolution CT scan, or a newer but more expensive (99m)Tc depreotide single photon emission CT (SPECT) scan, was the better first-choice examination for the work-up of pulmonary lesions. Furthermore, we examined whether a (99m)Tc depreotide SPECT scan was an appropriate second-choice examination for patients with indeterminate lesions. METHODS: 140 participants were included in the analysis. CT images were given a malignancy potential rating of 1, 2 or 3 with higher rating being indicative of disease. (99m)Tc depreotide SPECT images were graded either positive or negative. Histopathology and CT follow-up were used as reference standard. Sensitivity, specificity and diagnostic accuracy were calculated. RESULTS: Overall sensitivity, specificity and diagnostic accuracy of CT were 97%, 30% and 84%, respectively. Overall sensitivity, specificity and diagnostic accuracy of (99m)Tc depreotide SPECT were 94%, 58% and 76%, respectively. For indeterminate lesions sensitivity, specificity and diagnostic accuracy of (99m)Tc depreotide SPECT were 71%, 68% and 69%, respectively. CONCLUSION: Both CT and (99m)Tc depreotide SPECT made valuable contributions to the evaluation of pulmonary lesions. (99m)Tc depreotide SPECT results were not superior to CT results and did not contribute further to the diagnostic work-up. Regarding indeterminate lesions,( 99m)Tc depreotide SPECT sensitivity was too low.

Patients with ovarian cancer have elevated (51)Cr-EDTA plasma clearance early post-operatively.

Plasma clearance of (51)Cr-EDTA (Clp(EDTA)) is widely used to determine glomerular filtration rate prior to carboplatin based chemotherapy. We have observed that many patients with ovarian cancer have elevated Clp in the early post-operative phase compared to later phases. The purpose of this study was to examine whether this observation reflects a systematic difference. We retrospectively analysed data from 53 patients who had undergone surgery for ovarian cancer. Twenty-six patients had Clp(EDTA) measured early after the operation (mean, 8 days (range, 3-16 days)) (early group), and 27 patients had Clp(EDTA) measured late post-operatively (mean, 32 days (range, 19-48 days)) (late group). Clp(EDTA) values was measured before the first, third and fifth course of chemotherapy. Additionally, age, height, weight, cancer stage, ascites and tumour histology were noted. Mean Clp(EDTA) in the early group was significantly higher than in the late group (104+/-4.4 vs 89+/-3.5 ml.min(-1) per 1.73 m(2); P =0.005). Clp(EDTA) declined significantly in the early group from the first measurement after the operation until measurement before the third course of chemotherapy but remained constant in the late group. Clp(EDTA) was not correlated to ascites, cancer stage or tumour histology. It is concluded that patients with ovarian cancer have significantly higher Clp(EDTA) in the early post-operative phase than similar patients with Clp(EDTA) measured late post-operatively.

A 14-year follow-up of conservative treatment for vesico-ureteric reflux.

OBJECTIVE: To determine renal function in patients with vesico-ureteric reflux (VUR) during 14 years of conservative treatment (no surgery). PATIENTS AND METHODS: Sixty patients with VUR were consecutively included between 1981 and 1982. The degree of VUR was determined by conventional voiding cysto-uretherography (VCUG) after 3 months of prophylactic antibiotics. The VUR was grade I-IV, with grades III and IV characterized as high-grade VUR. In all patients, any urinary tract infections and bladder-urethral dysfunction were treated. Renal function and reflux were monitored by renal and bladder scintigraphy using 123I-hippuran and the glomerular filtration rate (GFR) was determined using the plasma clearance of 51Cr-ethylaminediamine tetra-acetic acid. RESULTS: Of the 60 patients who entered the study, 51 were followed for a mean of 13.7 years; nine patients were lost to follow-up. None of the patients underwent antireflux surgery. All patients were in good health and normotensive (except two with borderline hypertension). Of the 51 patients 21 had low-grade, 21 unilateral high-grade and nine bilateral high-grade reflux. In those with low-grade reflux both the mean renal split function on the most refluxing kidney and the GFR remained stable during the whole monitoring period. Eighteen patients who had a persistent reduction in renal split function or initially had had a significantly reduced functional share to the most refluxing kidney had their GFR re-assessed in adolescence. However, the body surface-corrected GFR remained constant. Total GFR and single kidney GFR increased significantly. CONCLUSION: A conservative treatment regimen in patients with VUR can ensure stable kidney function, although kidneys with a lower renal function at referral seem to have an impaired functional growth potential.

Myocardial perfusion imaging in breast cancer patients treated with or without post-mastectomy radiotherapy.

PURPOSE: To assess the occurrence and location of myocardial perfusion defects in left-sided mastectomized breast cancer patients, treated with or without postoperative radiotherapy according to the guidelines from the Danish Breast Cancer Cooperative Group (DBCG). PATIENTS AND METHODS: Seventeen left-sided breast cancer patients, with a median age of 59 years (range, 47-75 years), randomized to post-mastectomy irradiation plus systemic treatment, or systemic treatment alone, were examined after a median follow-up of 7.9 years (range, 6.0-12.2 years). The chest wall and the ipsilateral internal mammary nodes had been treated through two anterior-shaped electron fields, and the electron energy was chosen according to chest wall thickness, measured individually by ultrasound. The median absorbed dose was 50 Gy in 25 fractions, with 5 fractions/week. Information on clinical history was obtained and symptoms of ischemic heart disease (IHD), as well as major risk factors, were recorded. All patients had a physical examination, blood chemistry, electrocardiogram (ECG), chest X-ray and myocardial perfusion imaging by sestamibi-single photon emission computerized tomography (SPECT). SPECT-scanning was performed as a rest/dipyridamole 2-day protocol. The evaluation of regional myocardial perfusion was based on scintigrams using a 20-segment model. RESULTS: There was no significant difference between the scintigraphic findings in the two groups. Four of ten irradiated patients and four of seven non-irradiated patients showed scintigraphic defects. An anterior defect was found in one non-irradiated patient. CONCLUSIONS: This study does not indicate that the described radiotherapy technique induces detectable coronary artery disease. However, the small number of patients does not allow strong conclusions to be drawn.

Clearance and renal extraction of technetium-99m-L,L-ethylenedicysteine, I-131-ortho-iodohippurate and I-125-iothalamate in pigs.

99mTc-L,L-ethylenedicysteine (99mTc-EC) has been proposed as a 99mTc-labelled alternative to radio-iodinated ortho-iodohippurate (OIH) for renal imaging and evaluation of renal function. The kinetics of this new renal function agent were studied by a single-injection plasma clearance technique in pigs. 99mTc-EC, 131I-OIH and 125I-iothalamate were injected and the plasma concentration of the three tracers was followed for 240 min. Renal, hepatic and total plasma clearance were calculated. There was no difference between the renal plasma clearance of 99mTc-EC and 131I-OIH (175 +/- 9 versus 178 +/- 8 ml min-1, P = 0.43), whereas the difference between the total plasma clearance of 99mTc-EC and 131I-OIH was highly significant (268 +/- 16 versus 185 +/- 9 ml min-1, P = 0.0001). 99mTc-EC had a significant hepatic clearance of 83 +/- 10 ml min-1 whereas the hepatic clearance of 131I-OIH was negligible. Renal plasma extraction of both 99mTc-EC and 131I-OIH decreased significantly between 2 and 240 min post-injection from 0.85 to 0.45% for 99mTc-EC and from 0.93 to 0.57% for 131I-OIH. Red blood cell binding of 99mTc-EC and 131I-OIH was 6.1% and 20%, respectively. The protein binding of 99mTc-EC and 131I-OIH was 32% for both tracers. We conclude that 99mTc-EC is not a suitable tracer for measuring renal function by the single-injection plasma clearance technique in pigs. This is due to a decreasing renal extraction and a significant hepatic clearance.

Location of adrenal medullary pheochromocytoma by I-123 metaiodobenzylguanidine SPECT.

This is a retrospective study evaluating the efficacy of SPECT in the location of pheochromocytoma. Thirty patients with a suspected pheochromocytoma underwent I-123 metaiodobenzylguanidine (I-123 MIBG) SPECT 4 and 22 hours after intravenous injection of 370 MBq I-123 MIBG. SPECT was compared with planar scintigraphy, CT scanning, histology, and clinical course. Twenty-two-hour I-123 MIBG SPECT correctly identified 10 patients with adrenal medullary pheochromocytoma and correctly excluded pheochromocytoma in 19 patients. The sensitivity of the 22-hour MIBG SPECT was 1.00 and the specificity was 0.95. The positive predictive value was 0.95 and the negative predictive value was 1.00. In 16 patients, planar scintigraphy was compared with SPECT. SPECT located normal adrenal glands and tumors with greater confidence in three dimensions, but the patients with adrenal medullary pheochromocytoma were all correctly identified by planar scintigraphy. The results of SPECT and CT agreed in 29 of 30 patients (96.7%). I-123 MIBG SPECT for the location of pheochromocytoma has a high sensitivity, specificity, and positive and negative predictive values. I-123 MIBG SPECT or CT scanning alone were equally good for locating adrenal medullary pheochromocytoma but the combination of MIBG SPECT and CT makes it possible to distinguish between functioning and nonfunctioning adenomas. I-123 MIBG SPECT may be used alone or in combination with planar scintigraphy when three-dimensional location of a lesion is wanted.

Approximation of arterial input curve data in MRI estimation of cerebral blood-tumor-barrier leakage: comparison between Gd-DTPA and 99mTc-DTPA input curves.

Accurate and reproducible MRI measurements of the blood-brain-barrier transport rate constant Ki require measurements of the arterial Gd-DTPA concentration to characterise the arterial input function to the brain. Methods of measuring [Gd] in human plasma are not common practice in clinical departments. In this study we present a fast and easy method of substituting Gd-DTPA with 99mTc-DTPA as the 'tracer' to be measured for the characterisation of the arterial input curve in MRI blood-brain-barrier (BBB) measurements. Gd-DTPA and 99mTc-DTPA was injected intravenously as a bolus into six brain tumor patients during dynamic, fast gradient-echo MRI. Arterial blood samples were collected with an interval of 10(5) during imaging. 99mTc-DTPA and Gd-DTPA were measured in the same blood samples by scintillation counting and Inductively Coupled Plasma Atomic Emission Spectroscopy respectively. The two methods yield the concentrations of both the tracers in mmol/l Gd-DTPA and hence the results are directly comparable. The data results showed no statistically significant difference between the two methods. However, the 99mTc-DTPA method had fewer 'bad points' than the direct Gd-DTPA measurement method. The input curves were in agreement. Conclusively, we found that Gd-DTPA and 99mTc-DTPA were equivalent with regard to distribution and elimination-kinetics during the first 10 min after administration and, therefore, characterisation of arterial input curves may be done using simultaneous injection of 99mTc-DTPA and Gd-DTPA in facilities where means of measuring Gd-DTPA is not available.

Pharmacokinetics and dosimetry of [111In] F(ab')2 fragments against prostatic acid phosphatase after intraprostatic injection for immunoscintigraphy in prostate cancer.

The purpose of this study was to investigate the pharmacokinetics and dosimetry of using [111In]-labelled F(ab')2 fragments against prostate acid phosphatase (FC-3001, Orion Corporation Farmos, Finland) for the detection of metastatic prostate cancer. Five patients in all were subjected to intraprostatic injection of 1 mg FC-3001 labelled with 85-100 MBq [111In]. In four of the patients the biodistribution was studied by sequential whole-body counting, gamma-camera scintigraphy of the abdomen in antero-posterior and postero-anterior projections. Blood and urine samples were collected sequentially up to 72 h after injection. Initially, significant amounts of antibody fragments were released from the site of injection. After the first 4 h, 22.0% of injected antibody (2.2-41.3% ID) remained in the prostate and was slowly released with a final half-life of 80.4 h (49.9-141.8 h). Labelled antibody appeared in the blood shortly after injection and was cleared from the blood with a final half-life of 27.7-300.9 h. The liver, the bone marrow and, in two patients, the kidneys accumulated antibody fragments in significant amounts during the period of investigation. An apparent relationship between the initial whole-body clearance and renal uptake is described. The effective dose averaged 0.37 mSv/MBq (range 0.24-0.52 mSv/MBq). The highest equivalent doses were received by the kidneys (0.46-2.81 mGy/MBq) the liver (0.44-1.59 mGy/MBq) and the bone marrow (0.37-0.57 mGy/MBq). Only in two of the patients with known metastases were pathological foci seen. The disappointing imaging results were probably caused by the biphasic release of antibody from the prostate, and indicates that intraprostatic injection of this antibody has no advantage for imaging, as well as being unpleasant for the patient. The biodistribution of the antibody following release from the prostate is similar to but more variable than the biodistribution seen in patients after intravenous injection of labelled antibodies.