PET imaging of the 40 Hz auditory steady state response.

The auditory steady state response (aSSR) is an oscillatory electrical potential recorded from the scalp induced by amplitude-modulated (AM) or click/tone burst stimuli. Its clinical utility has been limited by uncertainty regarding the specific areas of the brain involved in its generation. To identify the generators of the aSSR, 15O-water PET imaging was used to locate the regions of the brain activated by a steady 1 kHz pure tone, the same tone amplitude modulated (AM) at 40 Hz and the specific regions of the brain responsive to the AM component of the stimulus relative to the continuous tone.

Brain imaging of the effects of lidocaine on tinnitus.

Using a single-blind placebo-controlled design, we mapped lidocaine related changes in neural activity, measured by regional cerebral blood flow (rCBF) with (15)O-H(2)O positron emission tomography. Intravenous lidocaine produced both increases and decreases in the loudness of tinnitus. The change in tinnitus loudness was associated with a statistically significant change in neural activity in the right temporal lobe in auditory association cortex.

Neuroanatomy of tinnitus.

We tested the hypothesis that tinnitus was due to excessive spontaneous activity in the central auditory system by seeking cerebral blood flow (CBF) changes that paralleled changes in the loudness of tinnitus in patients able to alter the loudness of their tinnitus. We found CBF changes in the left temporal lobe in patients with right ear tinnitus, in contrast to bilateral temporal lobe activity associated with stimulation of the right ear. The tones activated more extensive portions of the brain in patients than controls.

Staging of primary colorectal carcinomas with fluorine-18 fluorodeoxyglucose whole-body PET: correlation with histopathologic and CT findings.

Purpose: To evaluate the diagnostic usefulness of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) in patients with primary colorectal carcinomas.

Materials And Methods: Forty-eight patients with biopsy-proved (n = 44) or high clinical suspicion for (n = 4) colorectal cancer underwent whole-body PET after intravenous administration of 10 mCi (370 MBq) of FDG. FDG PET results were correlated with computed tomographic (CT), surgical, and histopathologic findings.

Development of oncology protocol using fluorine-18-FDG: one center's experience.

The major types of cancer studied at the authors' facility were colorectal (107 patients), head and neck (122 patients), gastric/esophageal (57 patients), lung (59 patients) and lymphoma (26 patients). This article presents guidelines and techniques for obtaining optimal PET studies. The authors devised these guidelines through trial and error and hope that by sharing them other facilities can avoid unnecessary mistakes and achieve better quality studies more efficiently.