Yasuto Onoyama

Multi-institutional studies on hyperthermia using an 8-MHz radiofrequency capacitive heating device (Thermotron RF-8) in combination with radiation for cancer therapy

A joint clinical trial of hyperthermia using a newly developed 8‐MHz radiofrequency (RF) capacitive heating device (Thermotron RF‐8; developed in cooperation with Yamamoto Vinyter Co. of Osaka) was performed under collaboration of seven institutions. Radiation with 4 Gy twice a week for a total of 40 Gy or 2 Gy five times a week for a total of 50 Gy was delivered. After irradiation, hyperthermia at 42.5°C ± 0.5°C for 40 to 60 minutes was given twice a week for a total of 10 times. Tumors examined in this trial were located in various depths in the body, and included those which were considered refractory to conventional treatments or radioresistant such as malignant melanoma and soft tissue tumors. Of the 63 tumors treated, 52.4% showed complete regression (CR); 19.0% more than 80% regression (PRa); 20.6%, 80% to 50% regression (PRb); and 8.0% no regression (NR). Our joint clinical trial demonstrated that hyperthermia with the use of the Thermotron RF‐8 is safe and effective in the treatment of radioresistant tumors located in superficial, subsurface, and in some cases deep regions, if the surface cooling is properly managed by the temperature‐controlled saline pad and electrodes of appropriate size are paired.

Techniques, Indications and Results of Intraoperative Radiotherapy of Advanced Cancers

After removing resectable lesions at operation, residual cancer nests were sterilized by irradiation before surgical closure. The great advantage of intraoperative radiotherapy lies in the treatment of lesions such as gastric cancers located near radiosensitive organs, and radioresistant tumors, such as soft-tissue sarcoma. Since the lesion is exposed directly to irradiation, a cancerocidal dose can be delivered without affecting normal structures. Clinical results have shown that cure can be expected following excision of the primary mass.

Thallium‐201‐chloride thyroid scintigraphy to evaluate benign and/or malignant nodules usefulness of the delayed scan

The purpose of this study is to evaluate benign and/or malignant thyroid tumors with 201TI thyroid scan. We studied 76 cases of histologically verified thyroid tumors, all seen as cold nodules on the 123I thyroid scan. 201TI thyroid scan was performed 5–15 minutes (early scan) and 3–5 hours (delayed scan) after intrayenous administration of 1.5–2.0 mCi of 201TI. In 35 (94.6%) of 37 malignant tumors (anaplastic carcinoma, six; papillary carcinoma, 23; follicullar carcinoma, five; epidermoid carcinoma, one; malignant lymphoma, 1), 201TI accumulated in the cold nodule of the 123I thyroid scan on both early and delayed scans. On the other hand, the delayed 201TI scan was negative in 35 out of 39 (89.7%) benign tumors. Employing early and delayed 201TI scans, we were able to differentiate most malignant thyroid tumors from those which were benign. False‐negative and ‐positive cases are discussed.

Radiation therapy of brain tumors in children

The case histories of 124 children irradiated for brain tumors were reviewed to determine survival rate and functional prognosis, with special reference to somatic growth. Five-year survival rates (29% of 97 patients with gliomas and 70% of 27 patients with non-gliomatous tumors) were approximately the same as in our adult series, despite the differences in histology and predilection. Although 70% of 42 long-term survivors had active, useful lives, stunted growth was observed in 15 of them. More attention should be directed to the growth of children irradiated for brain tumors.

MR appearance of Rathke's cleft cysts

SummaryTwo of three patients who proved to have symptomatic Rathkes cleft cysts presented with visual field deficit and all with diabetes insipidus. CT showed intra- and suprasellar cystic low density lesions with ring enhancement. MR showed intra-and suprasellar masses. On the T1-weighted images two of the three had hyperintense portions similar to fat and the other a hyperintense portion similar to white matter within the cysts. These portions were isointense to brain on the T2-weighted images in all cases. This characteristic intensity on MR images provides differentiation from cystic pituitary adenomas and cystic craniopharyngiomas, and leads to correct diagnosis of Rathkes cleft cyst.

MR imaging of intraspinal tumors--capability in histological differentiation and compartmentalization of extramedullary tumors.

SummaryMagnetic resonance (MR) images of 29 consecutive patients with intraspinal neoplasms (9 intramedullary tumors, 20 extramedullary tumors) were reviewed to evaluated the utility of MR imaging in distinguishing the intraspinal compartmental localisation and signal characteristics of each lesion. Compartment and histology of all neoplasms were surgically proven. MR correctly assigned one of three compartments to all lesions, 9 intramedullary, 14 intradural extramedullary (6 schwannomas, 3 neurofibromas, 5 meningiomas), and 6 extradural (3 schwannomas, 1 meningioma, 1 cavernous hemangioma, 1 metastatic renal cell carcinoma). All intramedullary tumors showed swelling of the spinal cord itself. In all five extradural tumors a low intensity band was visualized between the spinal cord and tumor. On the other hand, a low intensity band was demonstrated in no cases with intradural tumors. Visualization of this low intensity band is important in differentiating extradural from intradural-extramedullary lesions. We call this low intensity band, “the extradural sign”. Signal intensity of intradural tumors varied with histology. In extramedullary tumors, signal intensity of schwannomas was similar to that of the cerebrospinal fluid (CSF) both on T1 weighted (inversion recovery) and T2 weighted spin echo (SE) images. On the other hand, meningiomas tended to be isointense to the spinal cord on both T1 and T2 weighted SE images. We found relatively reliable signal characteristics to discriminate meningioma from schwannoma.

Radiation therapy of pineal tumors.

The case histories of 58 patients irradiated for pineal tumors were reviewed to assess indications and radiotherapy techniques. The survival rates were 61% at five years and 58% at 10 years in all cases. The five-year survival rate was 85% for 21 patients with germinoma, 69% of 26 with tumors not histologically confirmed, and zero for patients with glioma and teratoma. Doses ranging from 1,500 to 1,699 rets with or without decompression definitely improve the prognosis in pineal tumors. Field size and changes in CT scans during radiotherapy are also discussed.

Facial nerve neuromas: CT findings.

Although neuromas of the facial nerve are rare, they present with uniform clinical and radiological findings. Their pluridirectional tomography findings have been well described; however, the appearance of the intracranial extension of the neuroma which is best visualized by CT has not been emphasized. We report five cases of facial nerve neuromas with particular attention to their intracranial extension. For comparative purposes we also have reviewed 10 cases of acoustic and eight cases of trigeminal neuromas, all involving the cerebellopontine angle (CPA) and the middle cranial fossa. Two of the five facial nerve neuromas affected the second and third segments of the facial canal, and three involved both the CPA and the middle cranial fossa spreading across the midpetrosal bone. This type of tumor extension seems to be characteristic of facial nerve neuromas. In acoustic and trigeminal neuromas the tumor crossing toward the middle fossa takes place via the tentorial hiatus (acoustic) and the petrous apex (trigeminal).

Radiation therapy of craniopharyngioma.

The histories of 32 patients with craniopharygioma who had received radiotherapy after surgery were reviewed to assess the effect and adequacy of the radiation dose. The survival rates were 69% at 5 years and 60% at 10 years in all cases, but depended markedly on sex and age. Symptomatic improvement and histological changes in the irradiated tumor are also discussed. Radiation therapy with a dose ranging from 5500 to 6000 rads (approximately 1700 rets) after the first surgical intervention definitely improves the prognosis.

Magnetic resonance images of tuberous sclerosis

SummaryThe cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.