Supraophthalmic chemotherapy with long tapered catheter: distribution evaluated with intraarterial and intravenous Tc-99m HMPAO.
Shigeki AokiH. TeradaShigeru KosudaNobuyuki ShitaraHiroyuki FujiiKei SuzukiYasumichi KutsukakeJuichi TanakaYoshihiko SasakiT Okubo
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Abstract:
Supraophthalmic intraarterial chemotherapy has not become popular due to a high incidence of damage to the normal brain and eye. This damage is due to inhomogeneous distribution of the agent secondary to streaming and other flow-related phenomena. To try to minimize this complication, the authors developed a catheter and studied different infusion techniques. A 4.5-F catheter tapered to 2.5 F was used to perform supraophthalmic intraarterial chemotherapy in 26 patients with malignant gliomas. Forty-one of 45 catheterizations were successful. In 17 patients (20 procedures), technetium-99m hexamethyl-propyleneamine oxime (HMPAO) was then injected through the catheter and single photon emission computed tomography was performed to assess the cerebral distribution of the radiopharmaceutical with either a pulsatile or continuous infusion technique. Diffuse and relatively homogeneous distribution of Tc-99m HMPAO was observed with fast pulsatile infusion (10 of 10 procedures); however, inhomogeneous distribution was mostly seen with slow continuous infusion (eight of 10 procedures).Keywords:
Pulsatile flow
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Sequential liver scintiphotography with Tc-99m pyrophosphate (PYP) was used to prospectively evaluate its uptake patterns in hepatoma. The scintiphotos and time-activity curves of 40 cases were analyzed. Two distinct patterns of tumor activity were noted: gradual but complete extraction and trapping of Tc-99m PYP in hepatoma in 38% of the patients (group 1), and absence of subsequent Tc-99m PYP uptake in hepatoma after initial blood pool activity in 62% of the patients (group 2). Since extraction and trapping of Tc-99m PYP occur approximately in two fifths of the patients with hepatoma, we conclude that Tc-99m PYP liver scintigraphy is not worthwhile supplementing the conventional radionuclide studies for diagnosing hepatoma, even in the selected patients in the countries where the prevalence of hepatoma is high.
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Canine leukocytes were labeled with a γ-ray emitting isotope by permitting them to phagocytize technetium Tc 99m sulfur colloid particles in vitro and removing the unphagocytized particles by washing the cells. The labeled cells were reinfused intravenously into the donor dogs. Scintigraphic scans were performed 4 and 24 hours following the leukocyte infusion. In animals with sterile and infected intramuscular abscesses and pulmonary infections, it was possible to localize the lesions by scintigraphic scanning four hours following administration of labeled leukocytes. In one experiment, a positive scan was observed 24 hours after the leukocyte infusion. It was also shown that labeled leukocytes tend to concentrate in abscess fluid. These results suggest that technetium Tc 99m sulfur colloid-labeled leukocytes may be a useful diagnostic tool in localizing abscesses and inflammatory lesions in humans.
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The binding of technetium-99m sulfur colloid to in vivo thrombi was studied in a rat model of deep vein thrombosis. After thrombosis was induced by mechanical traumatization of a right femoral vein segment, technetium-99m sulfur colloid was injected into the peripheral veins of different experimental groups at intervals of 30 min and 1-7 days. Ratios of mean activity in traumatized right femoral vein segment to activity in control segments of left femoral vein (R/L ratios) ranged form 2.97-11.0 for all in situ venous thrombi studied. There was no relation between clot size and R/L ratios. The significant uptake ratios observed by us for venous thrombi up to 1 wk in age suggest that in vivo thrombus detection may be feasible by imaging with a gamma camera after technetium-99m sulfur colloid injection in a peripheral vein.
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Although [99mTc] diethylenetriaminepentaacetic acid (DTPA) is currently the most widely used radioaerosol, rapid alveolar clearance limits its usefulness for single photon emission computed tomography (SPECT) ventilation lung imaging. Previous research has shown that [99mTc]phosphate compounds have high alveolar deposition and slow clearance and thus provide suitable aerosols for pulmonary ventilation studies. We have compared the pulmonary retention and blood levels of [99mTc]pyrophosphate (PYP) and [99mTc]DTPA in eight normal nonsmoking male volunteers. These two radioaerosols have comparable pulmonary deposition. Technetium-99m PYP, however, has a much slower pulmonary clearance which allows sufficient time (20 or more minutes) for SPECT data acquisition using a single-headed rotating gamma camera. While the radiation absorbed dose to the lungs for [99mTc]PYP (0.31 rad/mCi) is greater than for [99mTc]DTPA (0.11 rad/mCi), it is at a clinically acceptable and safe level.
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Twenty-seven paired Tc-99m sulfur colloid (SC) and Tc- 99m RBC studies were evaluated for the detection of Gl bleeding. The only two positive Tc-99m SC studies had positive early Tc-99m RBC studies as well. There were 15 other positive Tc-99m RBC studies (three during the first hour) and these were associated with normal Tc- 99m SC scans. Approximately 70% of the positive Tc- 99m RBC studies occurred after 1 hour. Tc-99m RBCs should be the initial test in patients with Gl bleeding.
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The effect of direct current (DC) countershock upon myocardial technetium-99m stannous pyrophosphate (PYP) uptake was studied in 22 dogs. All eight dogs imaged had positive abnormal PYP scintigrams that were usually indistinguishable from experimental infarction. In three animals, additional areas of radionuclide uptake were seen in overlying noncardiac tissue. Left and right ventricular myocardial PYP uptake averaged (+/- SEM) 23 +/- 5 times control and 24 +/- 6 times control, respectively. These activity ratios occurred without reduction in regional myocardial blood flow (RMBF), and were associated with histologic evidence of necrosis. The necrosis was usually epicardial, corresponding to the transmural site of greatest PYP uptake. The magnitude of PYP accumulation and the weight of damaged tissue increased with increasing applied energy. Thus, PYP uptake following DC countershock could result in false-positive interpretation of acute ischemic myocardial infarction. Since RMBF is normal in regions of PYP uptake, the major determinant of radionuclide accumulation is the extent of cellular damage.
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Technetium-99m (99mTc)-pyrophosphatc was investigated for use as an indicator of intestinal infarction in intussuscepted bowel. Irreducible intussusceptions were created in eight adult mongrel dogs. Technetium-99m-pyrophosphate was then injected intravenously 24 and 48 hrs later for external scanning. In six of the dogs, infarction developed in the intussusception, and each demonstrated increased uptake of 99mTcpyrophosphate on in vivo scintiscans. The two dogs without infarction showed no increased uptake of the radionuclide. Well-counting and specimen scanning confirmed increased radionuclide in the infarcted intussusceptions. These observations suggest that 99mTc-pyrophosphate is a reliable indicator of the vascular compromise that sometimes occurs with intestinal intussusception.
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