Potentialities of Combined PET and CT in Diagnosis of Mass Pathologic Cerebral Lesions

I.V. Boikov, G.E. Trufanov, V.E. Parfenov, N.I. Dergunova, E.M. Mikhailovskaya, B.V. Martynov, B.E. Ivanishchak

Chair of Rentgenology and Radiology Medicomilitary Academy, Saint Petersburg, Russia

 

The goal of the present investigation was studying potentialities of combined PET and CT (PET/CT) from the point of view of revealing and differential diagnosis of cerebral pathologic formations, as well as estimation of efficacy of combined conservative and surgical treatment of malignant neoplasms.

There were 42 patients, who were examined either with the purpose of primary diagnosis (18) or after treatment (24). The BIOGRAPH (Siemens) apparatus was used. All the patients underwent spiral CT with I/V bolus enhancement and subsequent positron-emission scanning (after administration of 150-200 MBq of 18 F-desoxiglucose). Examination time was 15-20 minutes. PET/CT data were verified during intervention and on the basis of histological examination.

As for the patients of the first group, we diagnosed malignant and benign tumors in 11 and 6 of them respectively. Results in the second group coincided with data, verified earlier; a prolonged growth of neoplasms was diagnosed in 11 cases.

Hyperfixation of 18 f-desoxiglucose was watched in all patients with malignant neoplasms. There was no hyperfixation of the radiopharmaceutical preparation in 2 cases, though CT and MRI findings were indicative of malignant neoplasms. A subsequent histological examination confirmed presence of a benign tumor. Increased metabolism of 18 F-desoxiglucose was typical of a prolonged growth of tumor or its malignant degeneration. Benign tumors and their prolonged growth or relapse, as well as post-radiation necrosis (2 cases) were characterized by marked hypometabolism of 18 F-desoxiglucose. Quantitative estimation of 18 F-desoxiglucose metabolism was carried out with the help of the SUV index; it was compared with hemilateral cerebral areas.

Thus, the obtained data serve the grounds for coming to the following conclusion: combined PET/CT is a modern and highly informative method of radiation diagnosis, permitting to reveal pathologic cerebral formations and prolonged growth; to assess metabolism of the brain and affected areas by accumulation of a radiopharmaceutical preparation.