Differences In Lesion Location Research Articles

Exploration of the effect of blood lipids on the lesion distribution pattern in acute ischemic stroke based on MRI study with population standard spatial analysis

Objective: To explore the effect of blood lipids on the lesion distribution pattern in patients with acute ischemic stroke by using MRI technology based on population standard spatial analysis. Methods: The MRI data of 1 202 patients with acute ischemic stroke in General Hospital of Eastern Theater Command from January 2015 to December 2020 and Nanjing First Hospital from January 2013 to December 2021 were retrospectively collected, including 871 males and 331 females, aged 26 to 94 (64±11) years. According to the condition of blood lipids, they were divided into the dyslipidemia group (n=683) and the normal blood lipids group (n=519). After the automatic segmentation of diffusion-weighted imaging (DWI) images by artificial intelligence, the infarct sites were registered to the standard space which was used to draw the frequency heat map. The chi-square test was used to compare the difference in lesion location between the two groups. Generalized linear model regression analysis was used to observe the correlation between each blood lipid index and lesion site, and inter-group comparison and correlation analysis were used to observe the relationship between each blood lipid index and lesion volume. Results: Compared with the normal blood lipid group, the lesions in the dyslipidemia group were more extensive, mostly distributed in the occipital temporal region of the right posterior cerebral artery and the frontal region of the left middle cerebral artery. The brain regions of higher triglyceride(TG) and higher low-density lipoprotein cholesterol(LDL-C) groups were concentrated in the posterior circulation. The brain regions in the higher total cholesterol(TC) and lower high-density lipoprotein cholesterol(HDL-C) groups were concentrated in the anterior circulation(all P<0.05). In the anterior circulation infarct volume, the higher TC group was significantly higher than the normal TC group[(27.58±5.34) vs (17.73±1.18)ml, P=0.029]. In the posterior circulation infarct volume, the higher LDL-C group and the TG group were significantly higher than the normal LDL-C and TG groups[(7.55±2.51) vs (3.55±0.31) ml; (5.76±1.19) vs (3.36±0.30) ml](both P<0.05). Correlation analysis showed that TC and LDL-C were non-linearly (U-shaped) correlated with anterior circulation infarct volume (both P<0.05). Conclusions: Different blood lipids have effects on the distribution pattern and volume of ischemic stroke infarcts. Different hyperlipidemia is related to the specific distribution site and the larger extent of infarction.

Functional and Structural MRI Changes Associated With Cognitive Worsening in Multiple Sclerosis: A 3-Year Longitudinal Study (P11-3.003)

<h3>Objective:</h3> To apply a multiparametric MRI approach to identify mechanisms associated with cognitive worsening in multiple sclerosis (MS). <h3>Background:</h3> Heterogeneous processes may contribute to cognitive impairment in MS; however, its association with brain structural and functional MRI changes still need to be fully explored. <h3>Design/Methods:</h3> Brain dual-echo, 3D T1-weighted, diffusion-weighted imaging, and resting state (RS) functional MRI scans were acquired at baseline and after median follow up of 3.4 years in 35 MS patients and 22 healthy controls (HC). Associations between cognitive worsening at Rao’s battery and longitudinal changes in T2-hyperintense lesion location, WM microstructural damage, gray matter (GM) atrophy and RS functional connectivity (FC) were explored using tract-based spatial statistic, tensor-based morphometry and independent component analysis. <h3>Results:</h3> Fifteen (43%) MS patients were cognitively impaired at baseline and 10 (29%) showed cognitive deterioration at follow-up. At baseline, compared to HC, MS patients showed widespread WM damage and GM atrophy, and decreased RS FC in some clusters of executive control (ECN) and working memory networks (WMN). At follow-up, annualized volume loss of caudate nucleus was significantly higher in MS patients with vs without cognitive deterioration (−1.2% vs −0.2%, p&lt;0.05). No significant between-group differences in lesion location, WM microstructural changes or GM atrophy were found. Compared to stable MS patients, worsened patients showed decreased RS FC in right hippocampus of right WMN and in right insula of default mode network. In the opposite comparison, increased RS FC in left insula of ECN was found. <h3>Conclusions:</h3> While cognitively-stable MS patients showed increased RS FC in left insula, possibly reflecting a compensatory mechanism, cognitive deterioration in MS patients was associated with decreased RS FC in several functional brain networks, with limited GM atrophy progression. Our study suggests that, in MS patients already characterized by substantial structural damage, cognitive deterioration might be secondary to functional network collapse. <b>Disclosure:</b> Dr. Azzimonti has nothing to disclose. Mr. Preziosa has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bristol Myers Squibb . Mr. Preziosa has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Sanofi Genzyme. Mr. Preziosa has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Novartis. Mr. Preziosa has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Roche. Mr. Preziosa has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Merck. Paola Valsasina has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for ACCMED. Elisabetta Pagani has nothing to disclose. Olga Marchesi has nothing to disclose. Dr. Tedone has nothing to disclose. Carmen Vizzino has nothing to disclose. Dr. Filippi has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Bayer, Biogen Idec, Merck-Serono, Novartis, Roche, Sanofi Genzyme, Takeda, and Teva Pharmaceutical Industries. Dr. Filippi has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Bayer, Biogen Idec, Merck-Serono, Novartis, Roche, Sanofi Genzyme, Takeda, and Teva Pharmaceutical Industries. Dr. Filippi has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Springer Nature. The institution of Dr. Filippi has received research support from Biogen Idec, Merck-Serono, Novartis, Roche, Teva Pharmaceutical Industries, Italian Ministry of Health, Fondazione Italiana Sclerosi Multipla, and ARiSLA (Fondazione Italiana di Ricerca per la SLA). Maria Assunta Rocca has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Bayer, Biogen, Bristol Myers Squibb, Celgene, Genzyme, Merck Serono, Novartis, Roche, and Teva. The institution of Maria Assunta Rocca has received research support from Italian Ministry of Health, MS Society of Canada and Fondazione Italiana Sclerosi Multipla.

Resting-state functional alterations in patients with brain arteriovenous malformations involving language areas.

Brain arteriovenous malformations (AVMs) may involve language areas but usually do not lead to aphasia. This study evaluated resting-state functional alterations and investigated the language reorganization mechanism in AVM patients. Thirty-nine patients with AVMs involving language areas and 32 age- and sex-matched healthy controls were prospectively enrolled. The AVM patients were categorized into three subgroups according to lesion location: the frontal (15 patients), temporal (14 patients), and parietal subgroups (10 patients). All subjects underwent resting-state functional magnetic resonance imaging (rs-fMRI), and the amplitude of low-frequency fluctuation (ALFF) approach was applied to analyze rs-fMRI data. Language abilities were normal in all participants based on the Western Aphasia Battery. Compared with those of healthy subjects, ALFF values significantly increased (FDR corrected p < .01) in the anterior part of the right putamen in the frontal AVM subgroup, in the posterior part of the right inferior and middle temporal gyrus in the temporal AVM subgroup, and in the inferior lateral part of the left cerebellar hemisphere (lobule VIII) and the right inferior parietal lobule in the parietal AVM subgroup. Functional annotation using Neurosynth indicated that the ALFF t-map was only significantly positively associated with the language-related domain (FDR corrected p < .01). In patients with AVMs involving the language cortex, language network reorganization occurs to maintain normal language abilities. The brain areas recruited into the reorganized language network were located in the right cerebral and left cerebellar hemispheres, both of which are nondominant hemispheres. Differences in lesion location led to distinct reorganization patterns.

Combined SUVmax and localized colonic wall thickening parameters to identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci.

ObjectiveTo evaluate the detection ability of 18F-FDG PET/CT for identifying high-risk lesions (high-risk adenomas and adenocarcinoma) from incidental focal colorectal 18F-FDG uptake foci combining maximum standard uptake value (SUVmax) and localized colonic wall thickening (CWT). The secondary objective was to investigate the factors of missed detection of high-risk adenomas by 18F-FDG PET/CT.Patients and methodsA total of 6394 patients who underwent 18F-FDG PET/CT in our hospital from August 2019 to December 2021 were retrospectively analysed, and 145 patients with incidental focal colorectal 18F-FDG uptake foci were identified. The optimal cut-off value of SUVmax for 18F-FDG PET/CT diagnosis of high-risk lesions was determined by receiver operating characteristic (ROC) curves. SUVmax and localized CWT were combined to identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci. The characteristics of incidental adenomas detected and high-risk adenomas missed by 18F-FDG PET/CT were compared.ResultsOf the 6394 patients, 145 patients were found to have incidental focal colorectal FDG uptake foci (2.3%), and 44 patients underwent colonoscopy and pathological examination at the same time. In fact, 45 lesions, including 12 low-risk lesions and 33 high-risk lesions (22 high-risk adenomas, 11 adenocarcinoma), were found by colonoscopy. The area under the ROC curve of SUVmax for low-risk lesions and high-risk lesions was 0.737, and the optimal cut-off value was 6.45 (with a sensitivity of 87.9% and specificity of 58.3%). When SUVmax ≥6.45, the combination of localized CWT parameters has little influence on the sensitivity and specificity of detection; when SUVmax <6.45, the combination of localized CWT parameters can improve the specificity of detection of high-risk lesions, but the sensitivity has little change. In addition, the size of high-risk adenomas discovered incidentally by 18F-FDG PET/CT was larger than that of high-risk adenomas missed, but there was no significant difference in lesion location, pathological type or intraepithelial neoplasia between the two groups.ConclusionsThe combination of SUVmax and localized CWT parameters of 18F-FDG PET/CT helped identify high-risk lesions from incidental focal colorectal 18F-FDG uptake foci, especially for lesions with SUVmax <6.45. Lesion size may be the only factor in 18F-FDG PET/CT missing high-risk adenomas.

Racial Disparities in Magnetic Resonance Imaging and Perfusion-Diffusion Mismatch

Background The central concept of mismatch between perfusion and diffusion targets identified by magnetic resonance imaging offers an approximation of the tissue at risk of infarction if reperfusion is not achieved. This measure is becoming increasingly relevant in determining eligibility for and prognosis following thrombolytic and endovascular treatments, particularly at extended time windows. A few studies have shown that Black stroke patients are more likely to suffer small-vessel ischemic strokes and fewer cardioembolic strokes occluding large vessels. We investigated the relationship between race and arterial occlusion targets, including diffusion-perfusion mismatch. Methods The LESION study was a prospectively collected cohort of 1,092 consecutive subjects, NIHSS>3, scanned within 24 hours of symptom onset of time last known well. The study collected demographics, presentation including time from last known well (TLKW), imaging findings, and treatments. Perfusion and diffusion imaging targets and diffusion-perfusion “mismatch” was qualitatively assessed. Occlusion at any arterial location was documented and location used to characterize MCAO targets (MCA-M1 or M2) and endovascular targets (ICA or MCA-M1). Results Black subjects were younger (66.3 vs 75.4 years; p Conclusion Persistent racial and ethnic disparities are observed in the presentation of stroke with perfusion diffusion mismatch. The absence of differences in imaging targets present on MRA, particularly with large vessel occlusions, challenges the assumption that the difference in mismatch is due to differences in lesion locations.

Diffusion-weighted imaging in relation to morphology on dynamic contrast enhancement MRI: the diagnostic value of characterizing non-puerperal mastitis

ObjectivesTo demonstrate the value of diffusion-weighted imaging (DWI) in the characterisation of mastitis lesions.MethodsSixty-one non-puerperal patients with pathologically confirmed single benign mastitis lesions underwent preoperative examinations with conventional MRI and axial DWI. Patients were categorised into three groups: (1) periductal mastitis (PDM), (2) granulomatous lobular mastitis (GLM), and (3) infectious abscess (IAB). Apparent diffusion coefficient (ADC) values of each lesion were recorded. A one-way ANOVA with logistic analysis was performed to compare ADC values and other parameters. Discriminative abilities of DWI modalities were compared using the area under the receiver operating characteristic curve (AUC). P < 0.05 was considered statistically significant.ResultsADC values differed significantly among the three groups (P = 0.003) as well as between PDM and IAB and between PDM and GLM. The distribution of non-mass enhancement on dynamic contrast-enhanced (DCE) MRI differed significantly among the three groups (P = 0.03) but not between any two groups specifically. There were no differences in lesion location, patient age, T2WI or DWI signal intensity, enhancement type, non-mass internal enhancement, or mass enhancement characteristics among the three groups.ConclusionsADC values and the distribution of non-mass enhancement are valuable in classifying mastitis subtypes.Key points• Mastitis subtypes exhibit different characteristics on DWI and DCE MRI.• ADC values are helpful in isolating PDM from other mastitis lesions.• Distribution of non-mass enhancement also has value in comparing mastitis subtypes.

Microvascular pathology and morphometrics of sporadic and hereditary small vessel diseases of the brain.

Small vessel diseases (SVDs) of the brain are likely to become increasingly common in tandem with the rise in the aging population. In recent years, neuroimaging and pathological studies have informed on the pathogenesis of sporadic SVD and several single gene (monogenic) disorders predisposing to subcortical strokes and diffuse white matter disease. However, one of the limitations toward studying SVD lies in the lack of consistent assessment criteria and lesion burden for both clinical and pathological measures. Arteriolosclerosis and diffuse white matter changes are the hallmark features of both sporadic and hereditary SVDs. The pathogenesis of the arteriopathy is the key to understanding the differential progression of disease in various SVDs. Remarkably, quantification of microvascular abnormalities in sporadic and hereditary SVDs has shown that qualitatively the processes involved in arteriolar degeneration are largely similar in sporadic SVD compared with hereditary disorders such as cerebral autosomal arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Important significant regional differences in lesion location within the brain may enable one to distinguish SVDs, where frontal lobe involvement appears consistently with almost every SVD, but others bear specific pathologies in other lobes, such as the temporal pole in CADASIL and the pons in pontine autosomal dominant microangiopathy and leukoencephalopathy or PADMAL. Additionally, degenerative changes in the vascular smooth muscle cells, the cerebral endothelium and the basal lamina are often rapid and more aggressive in genetic disorders. Further quantification of other microvascular elements and even neuronal cells is needed to fully characterize SVD pathogenesis and to differentiate the usefulness of vascular interventions and treatments on the resulting pathology.

Evaluation of Sonographic Features for Patients with Urinary Bladder Paraganglioma: A Comparison with Patients with Urothelial Carcinoma

The goals of the work described here were to analyze the ultrasonographic characteristics of urinary bladder paraganglioma and to evaluate the use of ultrasonography (US) in diagnosis. Ten patients with bladder paraganglioma (3 males, 7 females) and 51 patients with urothelial carcinoma (37 males, 14 females) were enrolled. Ultrasonographic characteristics as well as clinical features were analyzed. Patients with urothelial carcinoma were significantly older than those with paraganglioma (62.9 y vs. 48.1 y, p = 0.001). The patients with paraganglioma had higher average systolic blood pressure than those with urothelial carcinoma (146.7 mm Hg vs. 130.7 mm Hg, p = 0.012). All bladder paragangliomas were solitary, and 40% were located on the dome. There was a statistically significant difference in location of lesions between the bladder paraganglioma and urothelial carcinoma groups (p = 0.014). The longest diameters in 80% of the bladder paragangliomas were in the range 1.1–3.0 cm; 60% were hypoechoic, and 40% were located in the submucosa of the bladder. Color Doppler revealed that 40% of the bladder paragangliomas were highly vascular. One patient with paraganglioma and four patients with urothelial carcinoma underwent contrast-enhanced ultrasound, which revealed rapid contrast enhancement and slow wash-out, with a non-enhanced area. Contrast-enhanced ultrasound of urothelial carcinomas revealed rapid homogeneous enhancement and variable wash-out patterns. Pre-operative ultrasonography detected all neoplasms of the urinary bladder in the 10 patients with pathologically confirmed paraganglioma, but made the correct diagnosis in only 2 cases (20%). Although there is overlap in US findings among different diseases, solitary, submucosal masses arising on the dome may be the key US imaging characteristic for bladder paraganglioma.

Adenoma, advanced adenoma and colorectal cancer prevalence in asymptomatic 40‐ to 49‐year‐old subjects with a first‐degree family history of colorectal cancer

First-degree relatives (FDRs) of patients with colorectal cancer (CRC) have an increased CRC risk. Few studies have addressed if adenoma and advanced adenoma risk is increased among individuals, 40-49 years of age, with a family history of CRC. Therefore, the aim of the study was to define the prevalence and location of adenoma, advanced adenoma and CRC, according to age, in asymptomatic individuals with a family history of CRC. Retrospective study of asymptomatic FDRs, 40 to ≥70 years of age undergoing first screening colonoscopy over a 3-year period, of CRC patients. Among 464 individuals studied, the prevalence of adenoma and advanced adenoma was 18.1% and 6.4%, respectively. According to age intervals, the prevalences of adenoma and advanced adenoma were 14% and 3.5%, respectively, in subjects 40-49 years of age; 14.4% and 6.3%, respectively, in subjects 50-59 years of age; 27% and 8%, respectively, in subjects 60-69 years of age; and 25% and 14%, respectively, in subjects ≥70 years of age; no significant difference was found among the four groups. No difference in lesion location was found, with similar numbers of preneoplastic lesions being present in the right colon and the left colon. CRC was diagnosed in three (0.64%) subjects, one of whom was in the 40-49 years age group. In our population of FDRs of CRC patients, 40-49 years of age, the prevalences of adenoma and advanced adenoma were similar to those observed in older subjects with the same CRC risk. Our data support the current indication to perform screening colonoscopy earlier than 45 years of age in subjects at high CRC risk.

The clinical and radiological spectrum of posterior reversible encephalopathy syndrome: the retrospective Berlin PRES study

The aim of the study was to characterize the clinical and radiological spectrum of posterior reversible encephalopathy syndrome (PRES) in a large cohort. The radiological report data bases of the authors' university hospitals were searched for patients with PRES. Various imaging features at onset of symptoms and on follow-up as well as clinical and paraclinical data were tabulated in those patients fulfilling the criteria for PRES. Exploratory univariate analyses were performed. A total of 96 patients with PRES were included into the study. Wide differences in lesion location, diffusivity, distribution pattern, edema severity, hemorrhage, underlying diseases, symptoms, mean arterial pressure (MAP) and coagulation status were encountered. Hemorrhage occurred significantly more frequently in patients with altered coagulation state and was significantly associated with higher edema grades and with the presence of cytotoxic edema. There was a significant difference in MAP between toxic associations with higher MAP in infection, eclampsy and autoimmune disorders, while lower MAP was found in chemotherapy and immunsupression. In 82% of patients complete or near complete resolution of edema was noted during follow-up. Higher MAP levels were associated with incomplete edema resolution. In 43% of patients residual lesions were seen with a relatively even distribution between focal gliosis, infarction, posthemorrhagic residua, atrophy and laminar necrosis. PRES in this large hospital-based retrospective study comprises a wide radiological and clinical spectrum. Residual lesions were encountered more frequently than commonly expected. Our results point towards a differential contribution of high blood pressure to the course of PRES in different underlying etiologies.

Cryoablation time-dependent dose-response effect at minimal temperatures (-80 C): an experimental study

AimsTo establish a temporal safety window for cryoablation at minimal temperatures and to assess the electrophysiological and histological changes as a function of the application duration.Methods and resultsTwenty mini-pigs underwent AV nodal cryoablation at −80°C without prior cryomapping. The duration of the cryoapplication following atrioventricular block (AVB) was randomized to 0, 10, 20, 40, or 60 s. Atrioventricular block was obtained in all animals after a median of 3 (1–8 interquartile range) applications. One week later, AV nodal conduction fully recovered in animals with application duration <10 s, whereas persistent AVB incidence increased as a function of time in animals with longer applications duration. Cryoablation application duration following AVB was the only independent predictor of persistent AVB (OR, 1.116; 95% CI, 1.013–1.229; P = 0.026). There was no difference in lesion location or size between animals with vs. those without persistent AVB at 1 week. However, animals randomized to longer application duration demonstrated higher degree of cell destruction and fibrotic content.ConclusionIn this closed-chest pig model, there was a relation between cryoapplication duration following AVB at −80°C and recovery of conduction. A safety window of at least 10 s was observed in all cases.

Pulmonary Abnormalities in Immunocompromised Patients: Comparative Detection with Parallel Acquisition MR Imaging and Thin-Section Helical CT

To compare parallel acquisition magnetic resonance (MR) imaging with thin-section helical computed tomography (CT) for depiction of pulmonary abnormalities suggestive of pneumonia in immunocompromised patients. The institutional review board approved this study; prior consent was obtained. Thirty consecutive neutropenic patients (10 women, 20 men; mean age, 51 years +/- 15 [standard deviation]; range, 25-75 years) with fever of unknown origin or clinical signs and symptoms of lung infection were examined with breath-hold single-shot half-Fourier turbo spin-echo MR imaging. To reduce image blurring and increase MR signal in the lungs, the echo time was shortened with generalized autocalibrating partially parallel acquisition (GRAPPA). Patients underwent thoracic CT (four detector rows and 1-mm section thickness [4 x 1 mm]; pitch, 6) as reference standard. Pulmonary abnormalities (ill-defined nodules, ground-glass opacity areas, and consolidation), their location and distribution, and lesion characteristics were analyzed at MR imaging by three readers, blinded to results of CT, in consensus. Frequencies were calculated for each feature; paired Wilcoxon rank sum test was used to examine whether differences between CT and MR imaging features were statistically significant (alpha < .05). Bonferroni adjustments were performed. Overall sensitivity, specificity, and positive and negative predictive values were determined. Twenty-two patients had pulmonary abnormalities at CT. In 21 (95%) patients, pneumonia was correctly diagnosed with MR imaging. One false-negative finding occurred in a patient with ill-defined nodules smaller than 1 cm at CT. One false-positive finding with MR imaging was the result of blurring and respiratory artifacts (sensitivity, 95%; specificity, 88%; positive predictive value, 95%; negative predictive value, 88%). There was no significant difference in lesion location and distribution. With parallel imaging (GRAPPA technique) and fast MR imaging, detection of pulmonary abnormalities is almost as good as with CT. MR imaging has a slight disadvantage in its lower capability to assist in characterization of specific internal features, such as cavitations.

Lobar Distribution of Lesion Volumes in Late-Life Depression: The Biomedical Informatics Research Network (BIRN)

White matter hyperintense lesions on T2-weighted images are associated with late-life depression. Little work has been carried out examining differences in lesion location between elderly individuals with and without depression. In contrast to previous studies examining total brain white matter lesion volume, this study examined lobar differences in white matter lesion volumes derived from brain magnetic resonance imaging. This study examined 49 subjects with a DSM-IV diagnosis of major depression and 50 comparison subjects without depression. All participants were age 60 years or older. White matter lesion volumes were measured in each hemisphere using a semiautomated segmentation process and localized to lobar regions using a lobar atlas created for this sample using the imaging tools provided by the Biomedical Informatics Research Network (BIRN). The lobar lesion volumes were compared against depression status. After controlling for age and hypertension, subjects with depression exhibited significantly greater total white matter lesion volume in both hemispheres and in both frontal lobes than did control subjects. Although a similar trend was observed in the parietal lobes, the difference did not reach a level of statistical significance. Models of the temporal and occipital lobes were not statistically significant. Older individuals with depression have greater white matter disease than healthy controls, predominantly in the frontal lobes. These changes are thought to disrupt neural circuits involved in mood regulation, thus increasing the risk of developing depression.

Optimal location of thalamotomy lesions for tremor associated with Parkinson disease: a probabilistic analysis based on postoperative magnetic resonance imaging and an integrated digital atlas.

Renewed interest in stereotactic neurosurgery for movement disorders has led to numerous reports of clinical outcomes associated with different treatment strategies. Nevertheless, there is a paucity of autopsy and imaging data that can be used to describe the optimal size and location of lesions or the location of implantable stimulators. In this study the authors correlated the clinical efficacy of stereotactic thalamotomy for tremor with precise anatomical localization by using postoperative magnetic resonance (MR) imaging and an integrated deformable digital atlas of subcortical structures. Thirty-one lesions were created by stereotactic thalamotomy in 25 patients with tremor-dominant Parkinson disease. Lesion volume and configuration were evaluated by reviewing early postoperative MR images and were correlated with excellent, good, or fair tremor outcome categories. To allow valid comparisons of configurations of lesions with respect to cytoarchitectonic thalamic boundaries, the MR image obtained in each patient was nonlinearly deformed into a standardized MR imaging space, which included an integrated atlas of the basal ganglia and thalamus. The volume and precise location of lesions associated with different clinical outcomes were compared using nonparametric statistical methods. Probabilistic maps of lesions in each tremor outcome category were generated and compared. Statistically significant differences in lesion location between excellent and good. and excellent and fair outcome categories were demonstrated. On average, lesions associated with excellent outcomes involved thalamic areas located more posteriorly than sites affected by lesions in the other two outcome groups. Subtraction analysis revealed that lesions correlated with excellent outcomes necessarily involved the interface of the nucleus ventralis intermedius (Vim; also known as the ventral lateral posterior nucleus [VLp]) and the nucleus ventrocaudalis (Vc; also known as the ventral posterior [VP] nucleus). Differences in lesion volume among outcome groups did not achieve statistical significance. Anatomical evaluation of lesions within a standardized MR image-atlas integrated reference space is a useful method for determining optimal lesion localization. The results of an analysis of probabilistic maps indicates that optimal relief of tremor is associated with lesions involving the Vim (VLp) and the anterior Vc (VP).

Myxobolus Cerebralis Infection in Rainbow Trout (Oncorhynchus Mykiss) and Brown Trout (Salmo Trutta) Exposed Under Natural Stream Conditions

From early April into mid-June 1977, sequential groups of juvenile rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta) were each exposed for 10 days to the parasite Myxobolus cerebralis by immersion in a stream inhabited by infected wild trout. Following incubation in a M. cerebralis-free facility, trout were subsequently killed, and heads and gill arches were examined by routine histologic methods. A grading scale to quantify lesion severity was developed and applied. Percentage infected, lesion severity scores, effects of water temperature and flow rates on percentage infected and lesion severity scores, and resulting pathology were determined for each species at each exposure period. The percentage of rainbow trout infected with M. cerebralis was significantly higher than the percentage of brown trout infected for each exposure period. The percentages of rainbow trout infected in exposure periods later in the calendar year were significantly higher than those in earlier periods. The percentages of brown trout infected were not significantly different among exposure periods. Overall average lesion severity scores were significantly higher in rainbow than in brown trout. Lesion severity scores in rainbow trout increased over time (a positive correlation with exposure period). Lesion severity scores were not significantly different for brown trout among exposure periods. A significant correlation existed between water temperature and percentage of rainbow trout infected; a significant correlation also existed between water temperature and lesion severity scores in rainbow trout. Similar correlations did not exist for percentage of brown trout infected or accompanying lesion severity scores. In rainbow trout, ventral calvarium was the most common site of M. cerebralis replication, followed by gill arches. In brown trout, lesions were virtually confined to gill arches. Early lesions consisted of foci of cartilage necrosis with small numbers of M. cerebralis developmental stages. More advanced lesions consisted of multifocal areas of cartilage necrosis with numerous M. cerebralis developmental stages and/or mature myxospores bordered and/or infiltrated by mono- and multinuclear leukocytes. Lesions in brown trout were smaller and had fewer associated leukocytes and M. cerebralis developmental stages and/or mature myxospores. Higher infection rates, lesion severity scores, and differences in lesion location in rainbow versus brown trout explain in part why numbers of rainbow but not brown trout have fallen in western rivers inhabited with M. cerebralis-infected trout.