Biomedical subjects

Charles Pelizzari

Publications and source records attributed to Charles Pelizzari.

8 recordsLinked to original sources

PubMed2006

OSP-Immunofluorescent remyelinating oligodendrocytes in the brainstem of toxically-demyelinated Wistar rats.

Central nervous system (CNS) remyelination following toxically-induced demyelination is a well known process. Oligodendrocytes constitute the bulk of the myelinating cells in the brain whereas Schwann cells overwhelm oligodendrocytes numbers in spinal cord remyelination. Despite the common knowledge of these facts, we still do not know completely the origin of both remyelinating cells. The present study investigated the participation of mature oligodendrocytes in remyelination after ethidium-bromide (EB) induced demyelination in the brainstem of normal and cyclosporin A-immunosuppressed Wistar rats. Thirty adult female rats were divided into three experimental groups. In group 1 the rats received a single intracisternal injection of 10 microL of 0.1% ethidium bromide (EB) in 0.9% saline (n=10); in group 2 the rats received the EB injection while immunosuppressed with cyclosporin A (n=10); in group 3 the rats received a single 10 microL injection of 0.9% saline while treated with cyclosporin A. The rats were killed at 15, 21 and 31 days after injection. Within the EB lesions, from 15 days onward many cells within the periphery of the lesions stained positive for OSP (oligodendrocyte specific protein) a marker for mature oligodendrocytes and myelin. This cell marking signals that, at least, part of the process of repairing the myelin sheaths is carried out by mature cells of the oligodendrocyte lineage.

Animals↗

PubMed2005

Opacity transfer function optimization for volume-rendered computed tomography images of the prostate.

RATIONALE AND OBJECTIVES: The selection of an opacity transfer function is essential for volume visualization. Computed tomography (CT) scans of the pelvis were used to determine an optimal opacity transfer function for use in radiotherapy. MATERIALS AND METHODS: On sample datasets (a mathematical phantom and a patient pelvis CT scan), standard viewing orientations were selected to render the prostate. Opacity functions were selected via (1) trapezoidal manual selection, (2) trapezoidal semiautomatic selection, and (3) histogram volume-based selection. Using an established metric, the errors using each of these methods were computed. RESULTS: Trapezoidal manual opacity function optimization resulted in visually acceptable images, but the errors were considerable (6.3-9.1 voxel units). These errors could be reduced with the use of trapezoidal semiautomatic selection (4.9-6.2 voxel units) or with histogram volume-based selection (4.8-7.9 voxel units). As each visualization algorithm focused on enhancing the boundary of the prostate using a different approach, the scene information was considerably different using the three techniques. CONCLUSION: Improved volume visualization of soft tissue interfaces was achieved using automated optimal opacity function determination, compared with manual selection.

Algorithms↗

PubMed2004

Impact of radioimmunoscintigraphy on definition of clinical target volume for radiotherapy after prostatectomy.

UNLABELLED: The goal of this study was to evaluate the role of radioimmunoscintigraphy (RIS) directed against prostate-specific membrane antigen in modifying postprostatectomy prostate fossa clinical target volume (CTV) definition. METHODS: The records of 25 postprostatectomy patients who received external-beam radiotherapy after prostatectomy and who underwent vessel-based RIS/planning CT registration were reviewed. For each patient, the CTV that would have been treated (CTV(pre)) before this registration was compared with that defined after the registration (CTV(post)). In addition, using a standard dose of 66 Gy in 2-Gy fractions, the corresponding bladder and rectum dose volume histograms were compared using 2 endpoints: volume receiving > or =60 Gy (V60) and area under the curve (AUC). RESULTS: The mean CTV(pre) vs. CTV(post) volumes were 24.4 vs. 35.0 cm(3), respectively (P = 0.032). The V60 results for CTV(pre) and CTV(post) were 32.7 vs. 41.0 cm(3), respectively, for the rectum (P = 0.168) and 33.9 vs. 46.6 cm(3), respectively, for the bladder (P = 0.015). The AUC results for CTV(pre) and CTV(post) were 4,027 vs. 4,516 Gy x cm(3), respectively, for the rectum (P = 0.396) and 4,782 vs. 5,561, respectively, for the bladder (P = 0.119). No Radiation Therapy Oncology Group grade 3, 4, or 5 (acute or late, gastrointestinal, or genitourinary) toxicity was observed. Two-year biochemical failure-free survival (with failure defined as 2 consecutive prostate-specific antigen rises above 0.2ng/mL) was 87% for the cohort. CONCLUSION: Incorporating RIS uptake resulted in significant modifications in CTV definition. The consequences of these modifications on the rectum V60 or AUC or on the bladder AUC were not significant, although the bladder V60 did increase. However, observed toxicity was low, with acceptable short-term biochemical control, suggesting that treatment to the modified CTV was tolerable.

Humans↗

PubMed2004

Influence of radioimmunoscintigraphy on postprostatectomy radiotherapy treatment decision making.

UNLABELLED: The aim of this study was to evaluate the role of radioimmunoscintigraphy (RIS) directed against prostate-specific membrane antigen (PSMA) in influencing postradical retropubic prostatectomy (RRP) radiotherapy (RT) decision making. METHODS: The records of consecutive patients who underwent RRP, who were referred for consideration of RT, and for whom an RIS scan was obtained were reviewed. The RT decisions, with regard to (a) the decision to offer RT and (b) the general volume to be treated [prostate fossa (PF) only versus PF + pelvis (P)] before knowledge of the RIS findings were charted. The RIS findings, with regard to uptake in the PF, uptake in the P, or extrapelvic (EP) uptake were tabulated. Then, the RT treatment decisions based on the RIS knowledge were evaluated and compared with the pre-RIS RT treatment decisions. RESULTS: Of the 54 patients originally referred for post-RRP RT, the initial decision was to recommend RT to the PF only in 52 cases and to PF+P in 2 cases. The RIS findings were as follows: PF only, 43 patients; PF+P, 8 patients; PF+EP, 2 patients; PF+P+EP, 1 patient. After knowledge of these RIS results, the decision to offer RT was withdrawn in 4 of 54 patients (7.4%; P = 0.046). Furthermore, RIS changed the general treatment volume (PF only to PF+P) in 6 of 54 patients (11.1%; P = 0.015). In total, RIS altered the RT decision in 10 of 54 patients (18.5%; P = 0.0067). Three-year biochemical failure-free survival (with failure defined as 2 consecutive prostate-specific antigen [PSA] rises above 0.2 ng/mL after PSA nadir) was 78%; no patient, disease, or treatment factor reached statistical significance on univariate or multivariate analysis. CONCLUSION: RIS was found to influence post-RRP RT decision making for the identification of patients not likely to benefit from RT and for guiding general target volume definition.

Aged↗

PubMed2004

Radioimmunoscintigraphy for postprostatectomy radiotherapy: analysis of toxicity and biochemical control.

UNLABELLED: Our goal was to evaluate the role of radioimmunoscintigraphy (RIS) directed against prostate-specific membrane antigen (PSMA) in influencing postprostatectomy radiotherapy (RT) toxicity and biochemical control. METHODS: The records of 107 postprostatectomy RT patients were reviewed. The group for whom no RIS scan was obtained (group A, n = 54) was identified as was the group for whom a RIS scan was obtained (group B, n = 53). Group B was further subdivided into those who had a RIS and CT-scan correlation to aid in treatment planning (subgroup B1, n = 40) versus those who did not (subgroup B2, n = 13). Gastrointestinal (GI) and genitourinary (GU) toxicities were reviewed for each of these groups and subgroups and compared. Biochemical failures (defined as 2 successive PSA rises after a nadir of >or=0.2 ng/mL) were identified to generate biochemical failure-free survival (BFFS) curves for each of the groups and subgroups. RESULTS: No significant differences in late toxicity were observed between any group or subgroup. However, acute GI toxicity was higher in group B versus group A (P = 0.026), and acute GU toxicity was higher in subgroup B2 versus subgroup B1 (P = 0.050). Overall, most toxicity was grade 1 or 2; only one case of grade 3 toxicity and no cases of grade 4 or 5 toxicity were observed. Three-year BFFS was higher for group B versus group A (80.7% vs. 75.5%) and for subgroup B1 versus subgroup B2 (84.5% vs. 71.6%). On multivariate analysis of pretreatment (age, race), surgical/staging (stage, grade, margin status, extracapsular extension, lymph node status, seminal vesicle invasion, post-radical retropubic prostatectomy [RRP] prostate-specific antigen [PSA] nadir, maximum post-RRP PSA, and RRP-to-RT interval), and treatment (hormone therapy, RT dose, RT technique, RIS scan, and RIS/CT correlation) factors on BFFS, the only covariate reaching significance was RIS/CT correlation (P = 0.042). CONCLUSION: A small BFFS advantage was observed in patients for whom RIS was used to guide RT decision making and treatment planning; however, this advantage only reached significance in this study for those for whom the RIS/CT correlation was used to guide target definition. The improved PSA control using RIS was achieved with a small increase in acute toxicity but with no observed change in late toxicity. These findings can serve as the basis for prospective studies in this area of investigation.

Cohort Studies↗

PubMed2003

Noninvasive identification of human central sulcus: a comparison of gyral morphology, functional MRI, dipole localization, and direct cortical mapping.

The locations of the human primary hand cortical somatosensory and motor areas were estimated using structural and functional MRI, scalp-recorded somatosensory-evoked potential dipole localization, expert judgments based on cortical anatomy, and direct cortical stimulation and recording studies. The within-subject reliability of localization (across 3 separate days) was studied for eight normal subjects. Intraoperative validation was obtained from five neurosurgical patients. The mean discrepancy between the different noninvasive functional imaging methods ranged from 6 to 26 mm. Quantitative comparison of the noninvasive methods with direct intraoperative stimulation and recording studies did not reveal a significant mean difference in accuracy. However, the expert judgments of the location of the sensory hand areas were significantly more variable (maximum error, 39 mm) than the dipole or functional MRI techniques. It is concluded that because expert judgments are less reliable for identifying the cortical hand area, consideration of the findings of noninvasive functional MRI and dipole localization studies is desirable for preoperative surgical planning.

Adult↗

PubMed2003

Transient inability to distinguish between faces: electrophysiologic studies.

It is not known with certainty at which level of face processing by the cortex the distinction between a familiar and an unfamiliar face is made. Subdural electrodes were implanted under the fusiform gyrus of the right temporal lobe in a patient who developed an unusual inability to distinguish differences between faces as part of the epileptic aura ("all faces looked the same"). A cortical region located posterior to the epileptic focus was identified that exhibited a maximum evoked response to the presentation of facial images (N165), but not to objects, scenes, or character strings. Evoked potentials elicited by a variety of visual images indicated that any perturbation away from novel whole-face stimuli produced submaximal responses from this region of the right temporal lobe. Electrical stimulation of this region resulted in an impairment of face discrimination. It was found that presentation of familiar faces (grandmother, treating physician) produced a different response from that observed for novel faces. These observations demonstrate that within 165 msec of face presentation, and before the conscious precept of face familiarity has formed, this cortical region has already begun to distinguish between a familiar and an unfamiliar face.

Adult↗

PubMed2003

A preliminary investigation of local tomography for megavoltage CT imaging.

We investigate the problem of reconstructing a two-dimensional (2-D) cross-sectional image of a tumor volume from a set of truncated MV projections that are produced by radiation therapy treatment beams. Our proposed approach is conceptually distinct from previously investigated approaches in that it utilizes a noniterative local tomography reconstruction algorithm. A local tomography reconstruction algorithm is implemented and systematically investigated using several sets of simulated and experimental MV projection data. We demonstrate that the conventional (nonlocal) filtered backprojection reconstruction algorithm cannot, in general, accurately reconstruct the edges and boundaries of low-contrast features from truncated MV projection data. We demonstrate that the local tomography algorithm is not adversely affected by projection truncation and can reconstruct accurately the boundaries of low-contrast structures within the region of interest from truncated MV projections.

Algorithms↗