Measured count-rate performance of the Discovery STE PET/CT scanner in 2D, 3D and partial collimation acquisition modes.

We measured count rates and scatter fraction on the Discovery STE PET/CT scanner in conventional 2D and 3D acquisition modes, and in a partial collimation mode between 2D and 3D. As part of the evaluation of using partial collimation, we estimated global count rates using a scanner model that combined computer simulations with an empirical live-time function. Our measurements followed the NEMA NU2 count rate and scatter-fraction protocol to obtain true, scattered and random coincidence events, from which noise equivalent count (NEC) rates were calculated. The effect of patient size was considered by using 27 cm and 35 cm diameter phantoms, in addition to the standard 20 cm diameter cylindrical count-rate phantom. Using the scanner model, we evaluated two partial collimation cases: removing half of the septa (2.5D) and removing two-thirds of the septa (2.7D). Based on predictions of the model, a 2.7D collimator was constructed. Count rates and scatter fractions were then measured in 2D, 2.7D and 3D. The scanner model predicted relative NEC variation with activity, as confirmed by measurements. The measured 2.7D NEC was equal or greater than 3D NEC for all activity levels in the 27 cm and 35 cm phantoms. In the 20 cm phantom, 3D NEC was somewhat higher ( approximately 15%) than 2.7D NEC at 100 MBq. For all higher activity concentrations, 2.7D NEC was greater and peaked 26% above the 3D peak NEC. The peak NEC in 2.7D mode occurred at approximately 425 MBq, and was 26-50% greater than the peak 3D NEC, depending on object size. NEC in 2D was considerably lower, except at relatively high activity concentrations. Partial collimation shows promise for improved noise equivalent count rates in clinical imaging without altering other detector parameters.

Expanding SimSET to include block detectors: performance with pseudo-blocks and a true block model.

We present a study that introduces two approaches to implementing block detectors into SimSET and compares their performance. SimSET is a photon tracking simulation package, which currently incorporates only detectors made of a solid annulus of scinitillator material. A pseudo-block approximation has been imposed on the solid annulus of conventional SimSET by discarding interactions in annulus segments that span the angular block gap. This yields blocks that are annulus segments, not rectangles. This is a quick and easy approximation of block structure, which brings SimSET results closer to actual scanner measurements. Even better agreement is expected with a deeper modification of the SimSET code that implements true rectangular blocks in the detector module (to be released late 2007/early 2008). This approach enables the greatest amount of variability and trueness to detail.We compare results from both block structure implementations to the conventional SimSET results and to measurements from a GE DSTE PET/CT scanner. Differences are evaluated in terms of sensitivities, crystal maps, and energy spectra, as well as in benchmark time tests of the simulation runs and their ease of use.Either implementation of block structure can aid in improving simulation accuracy by ameliorating one known cause of discrepancies, the geometric nature of the block detectors.

Detection of alcoholism relapse: comparative diagnostic value of MCV, GGTP, and AANB.

Mean red blood cell volume (MCV), plasma gamma glutamyl transpeptidase (GGTP), and plasma alpha amino-n-butyric acid (AANB) were measured in 245 patients undergoing treatment for alcoholism at the V.A. Medical Center, Bronx, N.Y. and Raleigh Hills Hospitals, Denver, Colo. AANB and GGTP, but not MCV, decreased following withdrawal from alcohol and during a period of abstinence. Among patients who relapsed, AANB and GGTP, but not MCV, increased in a majority of subjects. The combined use of AANB and GGTP identified 28/33 heavy drinkers, while 4/33 patients in remission had positive tests. In conclusion, measurement of AANB and GGTP are useful in documenting the success of treatment for alcoholism and in identifying patients who relapse following treatment for alcoholism.

Medical-behavioral treatment of the older alcoholic patient.

The purpose of the present research was to assess the treatment effectiveness of a multimodality alcoholism treatment program with older alcoholic patients. Treatment success was defined as 1 year of sobriety following inpatient treatment in a multicomponent program oriented around aversion conditioning to alcohol. A total of 87 patients, 65 years or older, were admitted, and a total of 78 patients were treated in the Raleigh Hills Hospital-Portland over a 2-year period. Descriptive psychological test data, demographic characteristics, and symptom history data were obtained for these patients and related to treatment outcome. This population of elderly alcoholic patients treated as successfully as younger patients. Their abstinence percentage combined for the two treatment years was 65.4% continuous sobriety over a 12-month follow-up period.

One year follow-up of total abstinence in chronic alcoholic patients following emetic counterconditioning.

The present study is a crossvalidation in the Fair Oaks Raleigh Hills Hospital of a 1970 outcome study by Wiens et al. from the Portland Raleigh Hills Hospital. The 1975 Fair Oaks crossvalidation sample included all 275 patients treated during 1975. These results were further recrossvalidated using all 290 patients treated in the Fair Oaks hospital during 1976. Results were 12-mo abstinence levels of 63% for the 1970 Portland sample and 39% and 50%, respectively, for the two Fair Oaks cross-validation samples. If the more stringent total abstinence without a slip of a single drink was the outcome measure used, these 1975 and 1976 12-mo abstinence levels became 33% and 43%, respectively. Additional analyses revealed the important role in these outcome rates of such demographic variables as Medicare recipient status, marital status, employment status, and a combined status of married and employed.

Replicable abstinence rates in an alcoholism treatment program.

Treatment outcome studies of alcoholism have historically had innumerable difficulties and controversy. Few investigators ever have reported a replication of their initial study results, let alone the crossvalidation of such initial results. This article provides results of a four-year replication study of a medical behavioral treatment approach. Comparisons of patients receiving a uniform treatment were made at yearly intervals. A few variables are identified to clarify who will or will not achieve and maintain follow-up sobriety, although it is admitted that our knowledge in this area is still rudimentary. These results affirm for the practitioner today that the alcoholic patient is treatable with a high probability of success. When the outcome of treatment is positive, the diagnosis and referral become crucial for alcoholism just as for other treatable diseases.