Kazuya Nishigauchi

Relationship between thallium-201 uptake and tumour proliferative ability in thyroid nodules

To evaluate whether thallium-201 scan can reflect tumour proliferative activity in thyroid nodules. We compared the degree of 201T1 uptake with the tumour proliferative ability as assessed immunohistochmically by the labelling index of proliferating cell nuclear antigen (PCNA) in malignant and benign thyroid nodules. The case material comprised ten benign and 31 malignant surgically resected nodules from a total of 41 patients.201TI scan was performed 5 min (early scan) and 2 h (delayed scan) after intravenous injection of 74 MBq of201Tl. The degree of201TI uptake was visually divided into three grades [from (-) to (++)], as compared with its uptake in normal adjacent thyroid tissue. Immunohistochemical staining of PCNA was performed using a monoclonal antibody for PC 10 on paraffin-embedded specimens. On both the early and the delayed scans, the mean PCNA index in the nodules with an intense201T1, i.e. (++), was significantly higher than that in nodules with a lower or with negative 201T1 uptake. The correlation was higher on the delayed 201T1 scan (P=0.009) than on the early scan (P=0.019). Our results indicate that201TI uptake may reflect the tumour proliferative activity of thyroid nodules, and this is especially true with regard to the uptake on delayed scans.

Radionuclide imaging in emphysema after lung volume reduction surgery

Three dimensional (3D) surface displays of dynamic Xe-133 and Tc-99m MAA SPECT were performed to evaluate regional lung function in two patients with pulmonary emphysema before and after thoracoscopic lung volume reduction surgery. The 3D displays were reconstructed using a color-illuminated, surface-rendering technique. For the Xe-133 studies, a fusion display of 3D equilibrium (EQ) and 3-minute washout (WO) images was used to show the distribution of Xe-133 retention, which were transparently seen within the entire lung contours delineated by the EQ image. In both patients, these 3D displays allowed an overview of the localized poorly functioning lungs with Xe-133 retention or reduced perfusion with geometric realism. The location and extent were more easily comprehended on the displays compared to the slice-by-slice presentations of tomograms. Postoperatively, the displays efficiently revealed restored function in the remaining lungs. The 3D surface displays of the two SPECT procedures providing topographic information of regional lung function appears to contribute to the treatment strategy of this surgery.

201Tl SPECT as an indicator for early prediction of therapeutic effects in patients with non-small cell lung cancer

This study retrospectively investigated the good parameters on thallium-201 chloride (201T1) SPECT for early assessment of the therapeutic effects in patients with non-small cell lung cancer.Based on tumor response as determined by chest CT scan about 9 weeks after the end of irradiation with adjuvant chemotherapy, the subjects were divided to the responder group (tumor regression > 50%, n = 13) and non-responder group (tumor regression < 50%, n = 13).201T1 SPECT was performed before and at the halfway through the course of therapy (average tumor dose, 27.4 Gy ± 4.5) in all the patients. SPECT was conducted twice 15 min (early scan) and 120 min (delayed scan) after intravenous injection of 148 MBq (4 mCi) of201T1. Tumor-to-contralateral normal lung tissue count ratios on both scans were calculated as early and delayed uptake ratios (EUR and DUR), and a retention index (RI) was also derived from these ratios.In the responder group, a significant decrease in DUR and RI halfway through the therapy was observed compared to pretreatment (2.6 ± 0.6 vs. 3.5 ± 1.0; p < 0.01, and -2.3% ± 25.5 vs. 37.4% ± 17.8; p < 0.001, respectively), even though EUR did not change significantly (N.S.). By contrast, in the non-responder group, there were no significant changes in any of these parameters (N.S.). When comparing DUR and RI for the two groups halfway through the therapy, DUR and RI were significantly lower in the responder group (both; p < 0.01), but no significant difference was noted in EUR (N.S.), and the percent reduction in tumor size did not correlate with the percent decrease in DUR or RI (N.S.).These results indicate that the extent of decrease in DUR and RI after therapy can be a useful parameter for early assessment of the therapeutic effects in patients with non-small cell lung cancer.

Demonstration of inguinal hernia by means of peritoneal99mTc-MAA scintigraphy with a load produced by standing in a patient treated by continuous ambulatory peritoneal dialysis

A 45-year-old man receiving continuous ambulatory peritoneal dialysis developed scrotal swelling and edema which was aggravated in the standing position. Physical examination failed to find inguinal hernia and although ultrasonography revealed the patent had processus vaginalias, it failed to prove its continuity to the peritesticular space of the tunica vaginalis. Peritoneal scintigraphy with intraperitoneal instillation of99mTc-Macroaggregated albumin followed by standing clearly demonstrated the connection. The use of the standing load makes possible faster visualization of a positive finding and more accurate diagnosis than examination in the supine position.

Delayed restoration of lung perfusion after removal of aspirated foreign body.

Tc-99m MAA lung scan contributed to the diagnosis of an aspirated endobronchial foreign body in a 2-year-old boy, although there was no radiographic evidence of obstruction. Despite the complete removal of the foreign-body, a follow-up scan performed 8 days after removal demonstrated incomplete restoration of perfusion to the ipsilateral lung. It is not easy to explain this delayed improvement of hypoperfuslon, but it may reflect a slow recovery of reflex vasoconstriction with a partial bronchial obstruction, or it may reflect reduced perfusion caused by persistent, subclinical inflammatory changes in the peripheral lung.

Radionuclide Angiography and Ventilation/Perfusion Studies in Two Patients With Systemic Arterial Supply to the Basal Segment of the Left Lung

The findings of radionuclide studies in two adult men with systemic arterial supply to the basal segment of the left lung without sequestration are reported. Radionuclide angiography with Tc-99m human serum albumin-diethylenetriamine showed that the lung was perfused by the systemic circulation rather than by the pulmonary artery. Ventilation and perfusion scans with Xe-133 and Tc-99m MAA showed a V/Q mismatch in this area, suggesting the presence of normal bronchial communication without a pulmonary arterial supply. These results also suggest the presence of a left-to-left shunt in the well-ventilated lung in this area. MRI and conventional angiography showed an aberrant artery arising from the descending thoracic aorta, supplying the basal segment of the left lung without a pulmonary artery. In both patients, left lower lobectomy showed normal alveobronchial structures without sequestration. Radionuclide angiography and ventilation/perfusion imaging appear to be reliable noninvasive methods for diagnosing this rare anomaly with a left-to-left shunt.

Superimposition of In-111 platelet SPECT and CT/MR imaging in intracardiac thrombus

An initial attempt to superimpose in-111-labeled platelet SPECT over CT/MRI in two patients with intracardiac thrombus is presented. One patient was a 65-year-old woman with a history of mitral and tricuspid valve replacement. This patient had a large thrombus measuring 74 x 43 x 34 mm in the right atrium. Fusion imaging with CT showed increased in-111 activity on the surface of the thrombus, which was visualized as circular activity on a planar image. The other patient was a 72-year-old woman who had a thrombus measuring 17 x 14 x 12 mm at the cardiac apex. Planar imaging showed two discrete areas of abnormal in-111 activity. Superimposition of the SPECT image over MR revealed that one of these areas corresponded to the small thrombus, whereas the other related to a previous subendomyocardial biopsy. In both patients, the activity ratio of the abnormal in-111 accumulation versus the cardiac chamber on SPECT was greater than that on planar images. The correlation of in-111 platelet SPECT and CT/MRI was useful in accurately localizing the intracardiac thrombus.

SPECT with In-111 autologous platelets to detect residual splenic tissue in two patients with relapsed thrombocytopenia.

In two patients with relapsed thrombocytopenia, the authors used SPECT with In-111 labeled autologous platelets to identify residual splenic tissue after splenectomy. One case involved a previously splenectomized patient with idiopathic portal hypertension, while the other had relapsed chronic idiopathic thrombocytopenic purpura (ITP). In both patients, SPECT showed a higher In-111 uptake in the splenic tissues compared with planar images. In the patient with ITP, a small accessory spleen had been overlooked on abdominal CT because of post-operative changes, but it was identified by superimposition of SPECT/CT images. These cases indicate that In-111 platelet SPECT is useful in detecting and localizing residual accessory splenic tissue associated with relapsed thrombocytopenia.

The effects of new platelet inhibitory drug E-5510 on platelet deposition on aortic bifurcation grafts : Assessment by indium-111-oxime labeled platelet imaging

The effects of a recently synthesized anti-platelet aggregation drug (E-5510) on platelet deposition in a knitted Dacron aortic graft underwent preliminary evaluation by In-111 oxime labeled platelet imaging. Seven patients undergoing aortofemoral bypass using this graft for occlusive disease were randomized into two groups: those receiving E-5510 and those receiving no medication. This agent was administered for 17 days postoperatively, and on the 14th day In-111 platelets were injected and images were acquired at 24, 48, and 72 hours. Platelet deposits in the grafts were assessed by the ratios of graft radioactivity to that of the adjacent native iliac arteries. Platelet deposition at the sites of anastomosis and deposition along the entire graft were normalized by initial deposition at 24 hours, and had significantly decreased at 72 hours in the three treated patients, while the normalized deposition increased progressively over time in the remaining four nonmedicated patients. E-5510 seems to have the potential to inhibit excessive platelet deposition on recently implanted grafts.

Preliminary Tl-201 SPECT for assessment of treatment efficacy in three patients with pancreatic cancer.

To evaluate treatment efficacy, Tl-201 SPECT was performed in three patients with pancreatic cancer. In all of the patients, the degree of Tl-201 uptake by tumor, evaluated from the tumor-liver uptake ratio of Tl-201 activity, correlated well with alterations in serum level of a tumor marker (CA 19-9, DUPAN-2) after treatment. One of the patients showed no tumor shrinkage on CT after treatment; however, Tl-201 SPECT demonstrated reduced uptake in the tumor coupled with a decreased level of CA 19-9. These results suggest that Tl-201 SPECT may become a new tool for assessing the efficacy of treatment in pancreatic cancer.