[Pitfalls in the assessment of radioresponse as determined by tumor regression: consideration based on the location and histologic constitution of tumors].

PURPOSE: To prove the following hypotheses regarding tumor shrinkage after radiotherapy. Tumors located on an outer tissue surface, e.g. esophageal tumors, shrink faster than parenchymal tumors, e.g. lymph-node metastasis, because two clearance mechanisms, exfoliation and absorption, can operate in the former type of tumors whereas only absorption can function in the latter. Tumors which are being controlled do not necessarily respond completely, because tumors are constituted not only of tumor cells but also stromal tissues that are difficult to be absorbed. MATERIALS AND METHODS: Long-term shrinkage patterns of a parenchymal tumor were determined by using 18 curatively irradiated hepatomas. Preoperatively irradiated thymomas (10) and lymph-node metastases (37) from head and neck cancers were examined histopathologically. Twenty-one esophageal cancers were used for intra-patient response comparison between the primary disease and the lymph-node metastases. RESULTS: Shrinkage patterns were generally biphasic: rapid exponential regression followed by a plateau phase. Histologically, thymomas generally consisted of predominant fibrous tissues and few remaining tumor cells. Radioresponse did not predict the presence of remaining cancer cells in the lymph nodes. Esophageal-cancer radioresponse was always higher for the primary disease than the lymph-node metastases. CONCLUSION: The location and histologic constitution of tumors must be taken into account in predicting radiocurability using radioresponse.

[Anomalous origin of the left coronary artery from the pulmonary trunk with myocardial infarction and severe left ventricular dysfunction in infancy--assessment of myocardial damage using SPECT studies with 201TlCl and 123I-BMIPP].

A 4-month-old male infant with Bland-White-Garland (BWG) syndrome complicated myocardial infarction was reported. Signs included tachypnea, coughing, and failure to thrive. However, there was no sign of myocardial infarction. A chest radiograph revealed cardiomegaly (CTR = 65%) and electrocardiogram showed abnormal Q waves in I, aVL, V6 leads. Cardiac catheterization and angiography revealed marked dilatation of left ventricle (end-diastolic volume = 384 ml/m2) and extremely depressed ejection fraction (16%), confirming the diagnosis of BWG syndrome. A 201TlCl-myocardial SPECT demonstrated apical defect and hypoperfusion in the anterolateral, inferoposterior walls, whereas 123I-beta-methyl-p-iodophenylpentadecanoic-acid (123I-BMIPP) SPECT showed a wider defect area. SPECT studies with 201TlCl and 123I-BMIPP, are useful to assess myocardial viability more accurately in BWG syndrome.

[Clinical assessment of 99mTc-MAG3 scintigraphy for impaired renal function].

The renal scintigraphy and clearance of 99mTc-mercaptoacetyltriglycine (MAG3) and 123I-ortho-iodohippuric acid (OIH) were compared in 12 patients with impaired renal function. The patients were first studied with MAG3 and then reinvestigated with OIH two days later. The MAG3 renal scintigraphy gave better quality and functional information in comparison with OIH. The MAG3 and OIH renogram showed identical relative kidney uptake and Tmax, but T1/2 of MAG3 was longer (p < 0.001). The plasma clearance of MAG3 was lower than that of OIH, but they correlated significantly (r = 0.87, p < 0.005). Also, the plasma clearances of MAG3 and para-aminohippuric acid (calculated by the standard clearance technique) showed good correlation (r = 0.77, p < 0.05). The urinary excretion during the first 60 min after injection was the same for the two radiopharmaceuticals. We conclude that 99mTc-MAG3 is a suitable alternative to 123I-OIH in renal scintigraphy.

Malignancy associated with chronic empyema: radiologic assessment.

Radiologic findings of six cases of malignancy associated with chronic empyema 5-39 years in duration were reviewed. Pathologic examination confirmed three B-cell non-Hodgkin lymphomas, one round-cell sarcoma, one mesothelioma, and one adenocarcinoma. Retrospective findings on plain chest radiographs suggested the occurrence of malignancy: increased radiopacity in the thoracic cavity, soft-tissue bulgings and/or unsharpness of fat planes in the chest walls, destruction of bone near the empyema, and extensive medial deviation of the calcified pleurae. Computed tomography delineated masses with soft-tissue attenuation more clearly than radiography in all cases. Magnetic resonance images of three cases were informative because empyema cavities were surrounded by low-intensity rims, and two of them showed a signal intensity different from that of necrotic tumors. Scintigraphy revealed increased uptake of gallium in all cases. Ultrasonography was useful for biopsy guidance. Every radiologist should know this entity in observation of chest radiographs obtained in patients with chronic empyema, and further radiologic assessment and aggressive biopsy are recommended if malignancy is suspected.