[Transient ischemic dilatation of the left ventricle observed on dipyridamole-stressed thallium-201 scintigraphy].

To assess clinical significance of transient ischemic dilatation of the left ventricle (TID) on dipyridamole-stressed 201Tl myocardial scintigraphy, 110 patients suspected with coronary artery disease, including 13 with normal coronary, 48 with single vessel disease, 30 with 2 vessel disease, and 19 with 3 vessel disease were analyzed. TID was visually and quantitatively assessed calculating the ratio of the area within the left ventricular region on the initial and delayed image (TID ratio). TID was observed in 3 of 1 vessel disease (6%), 5 of 2 vessel disease (17%), and 8 of 3 vessel disease (42%). None of normal coronary artery showed TID. In patients with multivessel disease (MVD), TID was observed more frequently (27%) than in patients with 1 vessel disease (6%) (p < 0.025). Furthermore, the TID ratio tended to be higher (1.15 +/- 0.11) than those with single vessel disease (1.03 +/- 0.03). To identify patients with MVD, TID had a sensitivity of 27% and a specificity of 95%. ECG changes were observed more often in patients with TID than those without TID. Five patients showing TID underwent coronary artery bypass graft surgery, TID disappeared postoperatively in each patient. In conclusion, TID on dipyridamole 201Tl scan seems to be a specific although not sensitive marker for detecting MVD.

99mTc-labelled monodisperse latex particles coated with amino or carboxyl groups for studies of GI function.

Latex particles coated with either amino or carboxyl groups were labelled with 99mTc. Two labelling methods were used: (1) direct labelling with tin reduction and (2) ligand exchange with tin pyrophosphate. Labelling efficiency and the radiochemical impurities were determined by thin-layer chromatography. Effect of [Sn2+] and pH on labelling yield was investigated to find the optimum labelling conditions. 99mTc-labelled latexes were administered orally to six normal subjects, and scintigrams from the abdomen were obtained at 1, 3, 6, and 24 h. Whole-body scintigrams were also taken by a gamma-camera. The first method was found to be efficient for carboxyl coated latexes and the second method for both types, giving > 98 per cent labelling efficiency. Labelled latexes were stable up to 24 h of testing at RT (> 99 per cent labelled). Scintigraphic studies showed that the labelled particles remained in GIT (98.11 +/- 0.92 per cent at 6 h) without dissociation of the label. No radioactivity was observed in the thyroid, stomach (at late images) and urinary bladder. This study demonstrated that latex particles coated with either amino or carboxyl groups can be efficiently labelled with 99mTc and used in the studies of GI function.

Visualization of bone pathologies and lung cancer with 99mTc-glucose phosphate: a comparative study.

Glucose phosphate (GP) labelled with 99mTc was used to obtain scintigraphic images of bone lesions in one group of patients (n = 28) and of lung tumors in another (n = 35). All bone lesions detected by 99mTc-MDP were also demonstrated by 99mTc-GP; all lung tumors except 4 were detected by 99mTc-GP, the failure rate being about the same as that for 67Ga. The use of 99mTc-GP is preferable to that of 99mTc-MDP because the former does not accumulate in normal bone; the advantage of 99mTc-GP over 67Ga lies in its better physical characteristics and in the fact that the result of the study is available within a few hours rather than three days.

Functional assessment of human gastrointestinal tract using 99Tcm-latex particles.

99Tcm-latex particles (LP) is a newly developed radiopharmaceutical for the evaluation of the gastrointestinal (GI) tract. Following oral ingestion, it passes through the entire GI tract undissolved. The purpose of the present investigation was to introduce the clinical application of 99Tcm-LP. A group of 11 healthy volunteers was studied. Following a 12 h fast, the subjects were given 150 ml of water containing 37 MBq of 99Tcm-LP orally. Dynamic images up to 2 h were recorded to document temporal progression of radioactivity. Static images of the abdomen and whole body were taken at intervals. In normal subjects the tracer arrival times at the caecum and sigmoid colon were 3.2 +/- 0.9 and 11.2 +/- 3.2 h, respectively. The average t1/2 value for gastric emptying, 50% colonic filling and small bowel transit time were found to be 21.6 +/- 5.6, 233 +/- 72 and 211 +/- 66.4 min, respectively. In conclusion, 99Tcm-LP has the potential of providing functional information of the GI tract.

[Clinical value of thallium-201 reinjection after delayed imaging in patient showing incomplete or no redistribution].

To asses clinical value of Tl-201 (Tl) reinjection after delayed imaging, 30 patients who showed incomplete or no redistribution in stress-delayed Tl myocardial scintigraphy were studied. Of 76 myocardial segments with incomplete or no redistribution on the delayed images, 29 segments (38%) showed improvement of Tl uptake after Tl reinjection. Reinjection was considered effective in 24 segments (32%) where no or little redistribution were observed on the delayed images but improved after reinjection. The contrast ventriculography showed less wall motion abnormality in the segments with improvement after reinjection than that without improvement after reinjection (regional wall motion score: 2.55 +/- 0.50 vs. 0.59 +/- 0.97 p less than 0.01). History of myocardial infarction was also significantly less in the former (p less than 0.05). We conclude that Tl reinjection is useful in cases showing no or equivocal redistribution on the delayed images.

Evaluation of 99mTc-labelled vitamin K4 as an agent for testicular imaging.

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 +/- 9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 +/- 6.3% as determined by TCA precipitation. Blood clearance of 99mTc-K4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 +/- 0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection. 99mTc-K4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.

Evaluation of 99mTc labelled monodisperse polystyrene/polyacrylate latex particles for the study of colon transit and morphology.

A new radiopharmaceutical for the study of colon transit time and morphology is proposed. Polymeric latexes, as monodisperse polymeric spheres (1-10 microns in diameter), were prepared by a coaxial dispersion polymerization of styrene and dimethylaminoethyl-methacrylate (DMAEA). They were labelled with 99mTc by the tin reduction method with high efficiency (greater than 99%). The label was stable up to 48 h at pH values of 1-8 at room temperature. Scintigrams obtained in rabbits after oral administration of 37 MBq of 99mTc-latex particles showed that greater than 90% of the dose remained in the gastrointestinal tract. The cumulative faecal excretion was 8.6 +/- 6.7 in 24 h and 21.3 +/- 13.8% in 48 h. In human studies the colon was well visualized at 4 h. The thyroid and the urinary bladder were not detected on scintigrams, indicating the stability of the label in vivo. Our results demonstrated that the radiopharmaceutical developed in the present study was ideal for the intended purpose.

Evaluation of MRI in moyamoya disease.

We present the MRI findings of six patients with angiographically documented moyamoya disease. All patients underwent CT and MRI, and MRI findings were compared with those of CT. In two patients both preoperative and postoperative MRI were performed. Most of the abnormalities secondary to moyamoya disease were clearly identified on MRI, which proved to be superior to CT, and it was revealed that the effectiveness of surgery as well as the severity of the disease could also be evaluated successfully by this powerful technique.

Increased iodine-123-iodoamphetamine uptake in hepatomas.

In the current study, two cases of hepatoma are reported in which N-isopropyl-(I-123)-p-iodoamphetamine (IMP) liver scan demonstrated increased accumulation in the tumor corresponding to the areas enhanced on contrast enhanced CT (CE-CT). In contrast, there was no IMP accumulation in the necrotic area of the tumor in which no enhancement was found on CE-CT. Thus, IMP liver scan seems to have the potential to assess the viability of a hepatoma as well as to detect and localize it.

Subtracted synthetic images in Gd-DTPA enhanced MR.

The evaluation of Gd-DTPA contrast enhancement (CE) in high intensity tissues on T1-weighted magnetic resonance images, such as fat and bone marrow, is quite difficult. In this study, we used subtraction and subtracted color images in an attempt to show more clearly the Gd-DTPA CE. In addition, we also carried out sequential post-Gd-DTPA imaging to assess the changes in enhancement of lesions with time. Twenty patients were studied with these methods and our results are illustrated.

Assessment of magnetic resonance contrast enhancement with Gd-DTPA: comparison with the uptake of Tc-99m-DTPA.

To compare the contrast enhancement of Gd-DTPA with the uptake of 99mTc-DTPA, a study was carried out in two steps. In the first step, images comparable in terms of data acquisition time and thickness were obtained after computer processing, and processed images of 99mTc-DTPA and Gd-DTPA enhanced MRI were compared from the morphological aspect. In the second step, the arterial blood concentration of Gd-DTPA and the effect of T2 shortening on signal intensity were studied. It was concluded that Gd-DTPA enhanced MRI can provide functional information analogous to that obtained from radionuclide studies, possibly enabling semiquantitative analysis of contrast enhancement to be performed.

Scintigraphic and MRI studies in a patient with granulocytic sarcoma accompanied with CML and myelofibrosis.

Indium bone marrow, bone, and gallium scans and magnetic resonance imaging (MRI) were performed in a patient with granulocytic sarcoma accompanied with chronic myelocytic leukemia (CML) and myelofibrosis. The significance and implications of the findings of these studies are discussed.

An improved method for the in vivo labelling of red blood cells with 99mTc in gated cardiac imaging.

Red blood cells of 10 patients were labelled with 99mTc by the in vivo method, 5 of the patients were orally administered with 400 mg potassium perchlorate at the time of stannous pyrophosphate injection and 5 ml blood was withdrawn at 10 min postinjection of pertechnetate to determine the labelling efficiency of RBC's. The RBC and plasma volumes were also determined in all patients by the 51Cr method. Our results indicated higher incorporation of injected radioactivity into RBC's in the perchlorate administered group (83.8% +/- 9.2%) compared to the other (58.5% +/- 22.0%) (P less than 0.01). The thyroid and stomach were visualized in the control group, but not in the perchlorate administered group. In routine application, 50 MUGA studies have been done with perchlorate administration with excellent results. In 60 patients without perchlorate administration previous to the present study the EF could not be determined in 6 patients (10%). Our results indicated that potassium perchlorate may be used routinely for in vivo labelling of RBC's to improve the labelling efficiency and the quality of gated cardiac imaging.