Search

Sensitivity and specificity of captopril renoscintigraphy (CRS) with Tc-99m DTPA has been analyzed in 41 cases, 16 with renovascular hypertension (RVH) and 25 with non-RVH. The sensitivity and specificity of the baseline study were 63% (10/16) and 63% (12/19), respectively, based on the split renal function study in which the lower limit of normal was assumed to be 42% of the total renal uptake. Captopril renoscintigraphy yielded 67% (12/18) sensitivity and 76% (19/25) specificity. The low specificity of CRS was due to the application of a prospective criterion of the captopril-induced reduction rate (CRR) of less than -20%, which was calculated from the renal uptake before and after captopril. When criteria of CRR less than -25% were used, the specificity of CRS was improved to 96%, but the sensitivity declined to 61%. Changes in the configuration of the renogram induced by captopril also had high specificity but low sensitivity. Renovascular hypertension was most likely when criteria for both CRR and the renogram were fulfilled. These criteria often were diagnostic in patients with bilateral renal artery stenosis that showed variable scintigraphic responses to captopril challenge. Captopril renoscintigraphy is a very specific means to evaluate RVH, but may have limitations in certain clinical situations such as poorly preserved function of the affected kidney, prior long-term administration of captopril, prior surgical manipulation of stenotic renal artery, and chronic renal parenchymal damage.

Tc-99m-labeled mercaptoacetyltriglycine (Tc-99m MAG3) is a recently introduced radioagent that is excreted by tubular function. The aim of this study was to test Tc-99m MAG3 as an imaging agent for renal scintigraphy and renal plasma flow measurement. Image quality was tested with four different administered doses of Tc-99m MAG3, 100 MBq, 200 MBq, 300 MBq and 400 MBq, in four patients each. All administered doses except 100 MBq were sufficient for visible inspection of the nephrogram and drainage images; however, an administered dose higher than 300 MBq was necessary to maintain the quality of the blood perfusion image. The blood clearance with Tc-99m MAG3 or I-131 orthoiodohippurate (I-131 OIH) was calculated within the same day by the single blood sampling method. The blood clearance with Tc-99m MAG3 was 1.2-fold lower than with I-131 OIH, but correlated well (OIH = 91.34 +/- 0.932 MAG3, r = 0.953, P < 0.001). The blood clearance with Tc-99m MAG3 also correlated with the percentage of renal uptake estimated by the count-based gamma camera method at 1.5 to 2.5 minutes after injection (ERPF = -59.13% +/- 16.87% uptake, r = 0.845, P < 0.01). The mean labeling yield of Tc-99m MAG3 was 97%. None of the patients complained of side effects from Tc-99m MAG3. Tc-99m MAG3 is concluded to have good properties as a tubular radioagent for dynamic renal scintigraphy and renal plasma flow measurement.

Phase II clinical study of mercaptoacetylglycyl-glycylglycinate (99mTc) technetium (99mTc-MAG3), a new scintigraphic and renographic agent, was performed to evaluate its safety, clinical usefulness and optimal dosage at 5 institutions in total 88 patients with mild renal or urinary disorders. There was no case showed adverse reaction in patients studied and the administration of the agent was proved to be safe. The effectiveness of the agent was evaluated and revealed to be effective in all cases analyzed. A range of dosage 200-400 MBq was found to be optimal, from image quality and clinical information obtained. It is concluded that 99mTc-MAG3 is a safe and useful radiopharmaceutical for the diagnosis of renal dynamic function.

The roles of planar imaging and SPECT with 99mTc-labeled RBC, US, Dynamic CT and angiography in the diagnosis of hepatic hemangioma were evaluated. The study group consisted of 18 patients with a total of 40 hemangiomas and 13 patients with a total of 21 non-hemangiomas. Among these patients, 5 patients with a total of 8 hemangiomas and 10 patients with a total of 14 non-hemangiomas were diagnosed by operation and biopsy. In all 40 hemangiomas, sensitivity for planar imaging was 35%, SPECT 50%, US 53%, Dynamic CT 82% and angiography 81%, respectively. When the tumor size was greater than 2.2 cm by SPECT and 2.8 cm by planar imaging, their sensitivity for both methods was 100%. Specificity for planar imaging was 100%, SPECT 95%, US 81%, Dynamic CT 100% and angiography 83%, respectively. One patient with hepatocellular carcinoma diagnosed by angiography showed increased uptake on SPECT. Because of the highest accuracy for SPECT in hemangioma greater than 2.0 cm, SPECT should be considered to be the method of choice for noninvasive diagnosis of hemangioma.

A single photon emission computed tomography (SPECT) with 201Tl chloride (Tl-201) was carried out prospectively in 50 patients with pulmonary nodules and its diagnostic value was compared with those of 67Ga citrate (Ga-67) and 99mTc-labeled hexamethylpropyleneamine-oxime (Tc-99m-HMPAO). Tl-201 SPECT provided 88% (early)-91% (delayed) sensitivity, 85% (early and delayed) specificity and 87% (early)-89% (delayed) accuracy. The sensitivity of the Tl-201 planar image was 56 (early)-62% (delayed), which was significantly lower than that of SPECT. Delayed SPECT images at 2 hour postinjection were more preferable to disclose the malignant pulmonary nodule than early SPECT images at 15 minutes postinjection. The application of SPECT with Ga-67 failed to improve the sensitivity of planar imaging for malignant pulmonary nodules. Tc-99m-HMPAO was concentrated in 62% of 13 patients with malignant pulmonary nodules, which was slightly higher than Ga-67 in 54% of 28 patients. In an analysis of the histologic types of lung cancer, the sensitivity of Tl-201 was not significantly different in all types. On the other hand, Ga-67 was positive only in 25% of 12 patients with adenocarcinoma. A combination of SPECT and Tl-201 is the best choice among routine scintigraphic techniques for depicting malignant pulmonary nodules. The Tl-201 SPECT image may play a complementary role in the characterization of pulmonary nodules which are revealed on a plain radiograph and computed tomography.

In vivo distribution of Tc-99m labeled recombinant tissue-type plasminogen activator (Tc-99m-rt-PA) was studied in control rats and thrombus-bearing rats. To compare fibrin binding in vivo with that in vitro, Tc-99m-rt-PA binding to fibrin gel in vitro was also imaged. Rapid blood clearance and accumulation into the liver and kidneys were observed in both control and thrombus-bearing rats. Accumulation in the stomach, which indicates instability of labeled rt-PA in vivo, was very low until two hours after injection. Tc-99m-rt-PA accumulation in the clots was higher than that in skeletal and heart muscles, although it was lower than in blood, liver, and kidneys. Administration of aprotinin, an antifibrinolytic agent, significantly prolonged clot accumulation of Tc-99m-rt-PA at 30 minutes after injection. These results suggest that fibrinolysis is responsible for the low rt-PA concentration in the clots. A scintigram of a thrombus-bearing rat demonstrated increased radioactivity at the clot forming site. On the other hand, Tc-99m-labeled human albumin, which was used as a control, was not accumulated in the clot. Tc-99m-rt-PA binding to fibrin gel in vitro was clearly imaged. By comparison, in vivo fibrin binding of Tc-99m-rt-PA was much lower than in vitro. The reasons for low thrombus uptake in vivo may be: 1. biochemical inactivation of extrinsically administered rt-PA by t-PA inhibitor. 2. fibrinolysis by rt-PA activated plasminogen. Overcoming these limitations will enable Tc-99m-rt-PA to reach the stage of clinical trials.

Tissue-type plasminogen activator (t-PA) is a thrombolytic agent that directly binds to fibrin formed in clots. In terms of radiolabeling and nuclear imaging, t-PA has several advantages in Tc-99m labeling: it is stable in acidic solution at pH 3, which is suitable for labeling Tc-99m by a method of stannous reduction and blood disappearance after administration is rapid, which is desirable for imaging targets using short-lived radionuclides. Recombinant t-PA was labeled with Tc-99m by a method of stannous reduction without significant degradation of biochemical activity, over 95% of which was retained after the labeling procedure. Labeling efficiency in paper chromatography was over 98%. The moiety of hydrolyzed Tc-99m that was not eluted through the Sephadex column was estimated to be less than 10%. Tc-99m labeled t-PA, however, appeared to become unstable when diluted with normal saline. Nevertheless, in in vitro fibrin binding, Tc-99m labeled t-PA showed high affinity with fibrin: 80% of 100 ng/ml of Tc-99m t-PA bound to 10(-5) mol of the fibrinogen. Preliminary animal studies also showed a concentration of Tc-99m labeled t-PA at fresh thrombi formed in the inferior vena cava. Tc-99m labeled t-PA appears to have potential for thrombus imaging and the preparation of an instant kit.

To assess the nature of adrenal mass incidentally discovered on computed tomography, adrenocortical scintigraphy with I-131-6 beta-iodomethyl-19-norcholest-5(10)-en-3 beta-ol (I-131 Adosterol) in 29 patients was retrospectively reviewed. All patients had no clinical symptoms and biochemical evidence of adrenal hyperfunction. Six of them had extra-adrenal malignancy. Increased tracer uptake on the side of adrenal mass was observed in 13 patients (concordant group): cortical adenoma in 8, macronodular hyperplasia in 1, no growing tumor in 1, and no further examination in the remaining 3 patients. No cancer patients were included in the concordant group. Symmetric uptake was seen in 9 patients (symmetric group): 1 cortical adenoma and 1 ganglioneuroma, 6 no growing tumor (two of them had malignancy), and no further examination in 1 patient. Decreased uptake were shown in 7 patients (dis-concordant group): metastasis in 4, adrenal cyst in 2, and no growing tumor in 1. Adrenocortical scintigraphy was helpful in distinguishing benign functioning adrenal masses from non-functioning adrenal masses such as metastatic tumor and cyst.

A case of a 63-year-old female with craniopharyngioma is reported. She first suffered from occult pituitary apoplexy and had recurrent enlargement and characteristic changes of a tumor during short periods. This patient was hospitalized after suddenly developing bitemporal hemianopsia. An intra-and suprasellar hematoma was revealed on computed tomography (CT) and magnetic resonance imaging (MRI). At the first operation, the hematoma was removed totally by the transsphenoidal approach, but tumor tissues were not identified. During the following 12 months, operations were repeated three times due to the recurrence and/or enlargement of a tumor associated with visual symptoms. Pathological diagnosis was squamous-type craniopharyngioma without any malignancy. Microscopic appearance of the tumor apparently changed during the clinical course. The characteristic findings were revealed respectively on MRI and CT. On the first preoperative MRI, a lesion of diffuse high signal intensity was observed on both T1 and T2 weighted images. At the second operation, the lesion was also revealed as having high signal intensity on T1 and T2 weighted images but the tumor had a large cyst with serous-yellowish fluid contents. A differential diagnosis was made on CT. At the third and fourth operations, the tumor was solid and had atheromatous contents. The lesion was revealed as having low signal intensity on T1 image and high on T2 respectively. Occult pituitary apoplexy with intra and suprasellar hemorrhage is very rare in cases of craniopharyngioma and only nine cases have been reported until now. It is also interesting with this high-aged patient that repeated recurrence and/or enlargement of a tumor with different microscopic appearances occurred during such short periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic renal scintigraphy on 15 patients of dissecting aneurysm of abdominal aorta extending below the renal arteries were retrospectively studied. The results were reviewed and classified into 3 types according to perfusion images and parenchymal tissue uptake: Type A: symmetric perfusion and parenchymal tissue uptake, Type B: asymmetrical perfusion and parenchymal tissue uptake, Type C: Delayed perfusion of one kidney and symmetric parenchymal tissue uptake. The number of patients who showed Type A, Type B, and Type C were 3 cases, 6 cases, and 6 cases, respectively. In all Type A and 3 of Type B, perfusion of bilateral renal arteries was mainly from true lumen. In the remaining 3 cases of Type B, 2 had one renal artery obstructed with thrombus; 1 had a deformity of one kidney (the blood supply was mainly from a false lumen), suggestive of renal infarction. On the other hand, in all 6 Type C cases, the renal artery where perfusion was delayed was apparently supplied from false lumen. It is suggested in this retrospective study that the findings in Type C, where delayed perfusion of one kidney and symmetric parenchymal tissue uptake were found, were due to the presence of delayed flow through the false lumen; and therefore, specific to cases where the main blood supply of one renal artery from false lumen.

Dynamic renal scintigraphy with 99mTc-DTPA before (baseline renography: BS-RG) and 1 hour after administration of 25 mg to 50 mg of captopril (captopril-enhanced renography: CP-RG) was performed in a selected series of 18 patients suspected of having renovascular hypertension. Final diagnosis was made by angiography and further clinical follow-up. Eight patients were considered as renovascular hypertension (RVH), 6 with bilateral renal artery stenosis (BRAS) and 2 with unilateral renal artery stenosis (URAS). The remaining 10 patients were non-renovascular (non-RVH). Two criteria were prospectively employed for evaluating positive response induced by captopril. Glomerular filtration rate (GFR) on BS-RG (GFRbase) and on CP-RG (GFRcap) was estimated by early (120-180 seconds) DTPA uptake by the kidney, and then captopril response rate (CRR) was calculated in the following: CRR = (GFRcap-GFRbase)/GFRbase X 100 (%). CP-RG was considered positive when it was less than 20%. Renogram shape was also independently evaluated. CP-RG was also considered positive when either a delay of time to peak activity of more than 5 min or conversion of renogram shape to an obstructive or non-functioning pattern was observed. The sensitivity and specificity of CRR and change in renogram were 50% and 80%, 63% and 100%, respectively. In BRAS, positive response was observed in the unilateral kidney alone which maintained relatively a good renal function. CP-RG could not differentiate RVH with URAS from that with BRAS. Four patients were followed after the surgical or angioplastic treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasonographic findings of 13 patients with cystic papillary carcinoma (CPC) of the thyroid gland were reviewed retrospectively correlating with pathologic findings. A 4-6 cm oval cystic structure with a 2-3 cm pedunculated projection of mass into the lumen was the characteristic sonographic findings of CPC. However, other sonographic findings of CPC simulated adenoma, nodular goiter or follicular carcinoma. Pathological investigation revealed that malignant cells tended more to be located in intracystic pedunculated mass and/or pericystic region than in the cyst wall. In most of the cases cyst walls were chiefly composed of granulomatous tissue with scattered malignant cells. These findings indicate that the needle biopsy should be done under ultrasonographic guidance to obtain sufficient material for accurate cytologic and/or pathologic diagnosis, thereby reducing the number of false negative cases.

Three cases with paraganglioma of urinary bladder are described. All cases complained of palpitation, headache and paroxysmal hypertension after micturition. 131I metaiodobenzylguanidine scintigraphy successfully visualized the tumor of the bladder in all three cases.

Scintigraphy with 67Ga-DFO-DAS-fibrinogen (67Ga-fibrinogen) was performed for the positive delineation of thrombi in patients with suspected venous or arterial thrombus formation. Five out of 17 patients showed 67Ga-fibrinogen accumulation corresponding to thrombus formation, as confirmed by other examination including radionuclide venography, contrast angiography, and CT scan. There was some difference in 67Ga-fibrinogen uptake between venous and arterial thrombi. With arterial thrombi, 67Ga-fibrinogen uptake was observed over one year after the appearance of clinical symptoms of dissecting aneurysm and arteriosclerosis obliterans. However, with venous thrombi, 67Ga-fibrinogen uptake occurred less than three weeks after the onset of venous edema. These results may indicate different mechanisms of thrombus organization between venous and arterial thrombi. Further, the thrombi age seems to be an important factor in analyzing the diagnostic accuracy of radioagents used for thrombus scintigraphy.

A 50-year-old man with traumatic CCF was presented. Spontaneous cure with closure of the fistula occurred just after orbital venography and it was confirmed by clinical examinations and followed up carotid angiography. The possible mechanisms responsible for the spontaneous cure of CCF were discussed.