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Tc-99m hexamethylpropylene amineoxime (HMPAO) was used to image cerebral perfusion changes in 20 patients with chronic schizophrenia (19 male and 1 female, aged 22-48, at an average age of 29.0). All were being given neuroleptic drugs. Twelve had electroconvulsive therapy. In addition, all had abnormal studies except one, who was normal and had a poor response to treatment. Ventricular dilatation and cerebral atrophy was seen in eleven patients, and 77 focal lesions were detected. Forty-two lesions demonstrated increased HMPAO retention, which was distributed as follows: 26 in the basal ganglia in 14 patients (12 bilateral, 2 unilateral); 10 along the sylvian fissure in the parietotemporal region; and 3 in the frontal and 1 in each of the temporal, parietal, and occipital regions. Thirty-five focal lesions exhibited decreased perfusion: ten parietal, eight frontal, seven temporal, six cerebellar, and four occipital lobes. This study demonstrates the potential value of Tc-99m HMPAO in schizophrenia and other psychiatric disorders.

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To evaluate 201Tl in the detection of the primary tumour, lymph node involvement and mediastinal spread we have studied a total of 188 patients with histologically proven lung cancer, breast cancer or malignant lymphoma. Ten patients with benign lung disease were also examined. Static images were performed 20 min after intravenous injection of 75 MBq of thallous (201Tl) chloride. The results were compared with those of standard staging procedures including CT scanning and mediastinal exploration. Thallium-201 imaging was highly sensitive in detecting the primary tumour (lung cancer 86%, breast carcinoma 100%, lymphoma 85%), but showed low sensitivity in detecting mediastinal spread or lymph node involvement. Thallium-201 uptake was also observed in active sarcoidosis (one case) and active TB (two cases). We conclude that 201Tl imaging is unlikely to have a clinically useful role in the diagnosis or staging of lung cancer, breast cancer or lymphoma.

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We have studied the mechanism of tumour uptake of 201Tl by in vivo and in vitro studies. In a series of patients with breast cancer (n = 26), lung cancer (n = 56) and lymphoma (n = 15), the time course of tumour uptake of 201Tl paralleled that in the myocardium with almost identical times of peak uptake being obtained in tumours and myocardium. In a patient with hepatic metastases from colonic cancer undergoing laparotomy, 99mTc labelled microspheres and 201Tl were injected into the hepatic artery and biopsies of metastatic and normal liver tissue obtained. The tumour to normal liver activity ratios for 201Tl were one tenth of those for 99mTc microspheres. In the final part of the study, cells from a lung cancer tissue culture line were incubated for 30 min with 201Tl with and without the addition of cardiac glycoside, which acts a sodium potassium pump blocker. The cells exposed to the cardiac glycoside showed markedly decreased uptake of 201Tl compared to the cells not so exposed (0.6% +/- 0.1% vs 11.8 +/- 0.7.2% of the administered dose). The mechanism of 201Tl uptake of tumours is similar to that in the myocardium. Sodium potassium pump activity appears to be more important than tumour blood flow. 201Tl uptake may provide a useful means of studying tumour viability.

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Following the intravenous injection of 75 MBq 201Tl-chloride we have assessed the uptake kinetics in the myocardium and in the primary tumour in 56 patients with lung cancer, 26 with breast cancer and 13 with mediastinal lymphoma. The time of maximal tumour uptake ranged from 8-20 min post-injection and did not differ significantly between lung cancer (mean +/- SD = 11.9 +/- 3.34 min), breast cancer (11.21 +/- 1.88 min) and lymphoma (11.76 +/- 3.25 min). The time of maximum cardiac uptake of 201Tl was 11.61 +/- 3.25 min. There was no significant washout of 201Tl from the tumours in the first hour after injection in the various malignant lesions studied. The time of maximal tumour to background activity was 18.3 +/- 0.59 min for lung cancer, 13.0 +/- 1.16 min for breast cancer and 16.7 +/- 1.04 min for lymphoma. The time course of 201Tl uptake in the tumours suggests that the mechanism of uptake is similar to that in the myocardium. The optimal time of 201Tl tumour imaging is from 20-60 min following injection and did not differ in various tumours studied.

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Tc-99m pertechnetate is known for its uptake and excretion by the mammary gland. Generally, lactating women are not advised to have any radioisotopic studies. If it is necessary to have one, it is recommended that they do not breast-feed their children for at least 24 hours. Congenital absence of the mammary gland is a rare condition. This case was accidently discovered. Nuclear medicine physicians should be aware of the value of clinical examination of patients, and that not every absent or asymmetric breast shadow is due to surgical resection.

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