Brain effects of TMS delivered over prefrontal cortex in depressed adults: role of stimulation frequency and coil-cortex distance.

Relative regional brain blood flow was measured in 23 clinically depressed adults by using ECD SPECT at baseline and again during actual prefrontal transcranial magnetic stimulation (TMS) following 5 daily sessions of TMS. TMS over prefrontal cortex caused increased activity in cortex directly under the stimulation (inversely correlated with distance from scalp to cortex) and decreased activity in remote regions (anterior cingulate and anterior temporal poles). High-frequency rTMS (20 Hz) caused more relative flow immediately below the TMS coil than did low-frequency rTMS (5 Hz). Confirming the hypotheses tested, repeated daily TMS over the prefrontal cortex in medication-free depressed adults appears to change both local and remote blood flow in a manner that may also depend on the frequency of stimulation and coil to outer cortex distance.

Changes in prefrontal cortex and paralimbic activity in depression following two weeks of daily left prefrontal TMS.

Twenty-two depressed adults were scanned with perfusion single-photon computed emission tomography before and after 2 weeks of left perfrontal transcranial magnetic stimulation (TMS) in a parallel design, double-blind treatment study. At medication-free baseline, across all subjects, blood flow in the bilateral medial temporal lobes, left prefrontal cortex, and caudate significantly declined with increased depression severity. Also at baseline, depressed adults who responded to TMS, compared with nonresponders, showed increased inferior frontal lobe activity. Following treatment, there was an even greater difference in inferior frontal blood flow in responders compared with nonresponders, and the negative baseline correlations between depression severity and limbic and prefrontal blood flow disappeared. These results suggest that in depressed adults, 10 days of prefrontal TMS affects prefrontal and paralimbic activity, which may explain its antidepressant effects.

Multiple previous alcohol detoxifications are associated with decreased medial temporal and paralimbic function in the postwithdrawal period.

BACKGROUND: Functional neuroimaging studies after alcohol cessation have demonstrated that chronic alcohol use globally reduces neuronal activity for several weeks. Less is known about the effects of previous alcohol use patterns on regional brain activity. Multiple previous alcohol detoxifications are associated with a worse clinical course and increased risk of seizures, perhaps due to sensitization of key brain structures. We performed the following imaging study in alcoholics in the postwithdrawal period to determine if blood flow in medial temporal structures would differ as a function of previous alcohol use (i.e., whether regions were kindled or sensitized due to multiple detoxifications). METHODS: Fourteen adults meeting DSM-IV criteria for alcohol dependence (mean age 35, 8 SD; 10 men) and participating in a double-blind detoxification medication study underwent a brain perfusion Tc99 m-ECD (Neurolite) single photon emission computed tomography scan on days 7 through 9 (mean 7.6, .5 SD) after their last drink and 2 to 3 days since their last detoxification medication. Seven nonpsychiatrically ill, nonalcohol-dependent healthy adults were scanned as control subjects. RESULTS: Alcoholics compared with controls had widely reduced relative activity in cortical secondary association areas and relatively increased activity in the medial temporal lobes (p < 0.01). Five alcoholic patients with > or = 2 previous detoxifications were compared with five patients in their first detoxification (age and detoxification medication matched). Multiple detoxification patients had significantly lower relative activity in bilateral anterior temporal poles and medial temporal lobes and in visual cortex (p < 0.01) compared with first episode patients. CONCLUSIONS: These studies are consistent with other studies comparing alcoholics and controls. They also suggest that on day 7 of detoxification, alcoholic subjects with multiple previous detoxifications have decreased visual cortex, medial temporal lobes, and anterior paralimbic blood flow, compared with those in their first detoxification. Further studies seem warranted to confirm these initial exploratory results.

Ultratag RBC kit for combined cardiac first-pass and multigated acquisition studies.

UNLABELLED: The authors developed a procedure to use the in vitro Ultratag (Mallinckrodt, St. Louis, MO) red blood cell (RBC) labeling kit for both first-pass (FP) and multigated acquisition (MUGA) studies with a high specific activity in a reduced volume (50 mCi/0.5 ml) and a high labeling efficiency that can be used with a single-crystal camera to yield a quality study. METHODS: A packed red blood cell (PRBC) bolus was created by two methods: (a) reducing the volume of the components of the Ultratag kit and (b) centrifuging the final dose volume. The labeling efficiency of each bolus was evaluated, each PRBC bolus was visually inspected for clots and percent hemolysis was assessed using a hemocytometer at 30 min, 1 hr and 2 hr postcentrifugation. RESULTS: Use of the first method, the 50% kit, provided the best results. However, the resulting volume from this kit only approached 1 ml, which is not clinically adequate for a first-pass study. In the second method, the total volume was centrifuged to form a PRBC bolus, which appeared to be stable in the syringe for at least 2 hr. A combined FP/MUGA study from a centrifuged 50% reduced kit was performed in one normal subject as a preliminary assessment of the clinical utility of this procedure. The image quality of the scan is diagnostically adequate. CONCLUSION: By using the in vitro Ultratag kit, a compact PRBC bolus was created that was stable in the syringe and could be reinjected safely into the patient for combined cardiac FP/MUGA studies.