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P M Desmond

Publications and source records attributed to P M Desmond.

At least 19 recordsLinked to original sources
PubMed2005

Elevated hematocrit is associated with reduced reperfusion and tissue survival in acute stroke.

BACKGROUND: Elevated hematocrit (Hct) contributes to blood viscosity and has an adverse effect in acute stroke. The authors investigated the influence of Hct on tissue fate using serial MRI in acute stroke patients. METHODS: The effects of Hct on reperfusion, penumbral salvage, and infarct expansion in 64 patients presenting within 24 hours of stroke onset were measured. MRI was performed at baseline (< 24 hours), days 3 to 5, and 90 days from stroke onset. RESULTS: Median Hct was 42% with a bimodal distribution. There was a strong inverse relationship between Hct and reperfusion (Spearman rho = -0.74, p < 0.0001). The odds of major reperfusion (> 50% resolution of the baseline perfusion-weighted imaging deficit) were significantly lower with increasing Hct (odds ratio [OR] = 0.53; 95% CI = 0.97 to 1.00), independent of age, perfusion, and diffusion lesion volumes and recombinant tissue plasminogen activator (rtPA) administration. There was a trend toward reduced penumbral salvage at days 3 to 5 with increasing Hct (p = 0.06, 95% CI = -4.76 to 0.14). An increasing Hct was a significant predictor of infarct growth (OR = 1.26, 95% CI = 1.00 to 1.59), independent of baseline perfusion and diffusion volumes and glucose. The effect of Hct on reperfusion and infarct expansion was similar irrespective of rtPA administration (p = 0.31) and independent of smoking status. CONCLUSIONS: Higher hematocrit (Hct) values have a significant independent association with reduced reperfusion and greater infarct size after ischemic stroke. An elevated Hct may also be a potential physiologic determinant of reduced penumbral salvage.

Adult↗
PubMed2001

Comparison of MRI perfusion imaging and single photon emission computed tomography in chronic stroke.

There have been few direct comparisons between MR perfusion-weighted imaging (PWI) and established perfusion imaging techniques, and none in chronic stroke. We therefore studied 17 chronic hemispheric infarction patients (mean, 90 days) and compared hypoperfusion volumes determined from PWI maps of relative cerebral blood flow (rCBF) and volume (rCBV), and mean transit time (rMTT) with those measured with (99)Tc-HMPAO single photon emission computed tomography (SPECT). Comparisons were also made between infarct size (T(2)-WI) and clinical scales. Correlations were found between lesion location and volume in all three PWI hemodynamic parameter maps with clinical state and lesions on SPECT and T(2)-WI. In 3 patients, rCBF and rCBV lesions extended well beyond the borders of moderate-sized infarctions. We conclude that in chronic stroke, PWI can delineate regions of abnormal perfusion that reflect the degree of functional impairment and structural damage. The finding of peri-infarct hypoperfusion suggests that PWI may have the potential to provide a rapid and non-invasive template against which interventional strategies aimed at promoting functional recovery may be investigated.

Aged↗
PubMed2001

Perfusion magnetic resonance imaging maps in hyperacute stroke: relative cerebral blood flow most accurately identifies tissue destined to infarct.

BACKGROUND AND PURPOSE: In ischemic stroke, perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) provide important pathophysiological information. A PWI>DWI mismatch pattern suggests the presence of salvageable tissue. However, improved methods for distinguishing PWI>DWI mismatch tissue that is critically hypoperfused from benign oligemia are required. METHODS: We investigated the usefulness of maps of relative cerebral blood flow (rCBF), volume (rCBV), and mean transit time (rMTT) to predict transition to infarction in hyperacute (<6 hours) stroke patients with PWI>DWI mismatch patterns. Semiquantitative color-thresholded analysis was used to measure hypoperfusion volumes, including increasing color signal intensity thresholds of rMTT delay, which were compared with infarct expansion, outcome infarct size, and clinical status. RESULTS: Acute rCBF lesion volume had the strongest correlation with final infarct size (r=0.91, P<0.001) and clinical outcome (r=0.67, P<0.01). There was a trend for acute rCBF>DWI mismatch volume to overestimate infarct expansion between the acute and outcome study (P=0.06). Infarct expansion was underestimated by acute rCBV>DWI mismatch (P<0.001). When rMTT lesions included tissue with moderately prolonged transit times (mean delay 4.3 seconds, signal intensity values 50% to 70%), infarct expansion was overestimated. In contrast, when rMTT lesions were restricted to more severely prolonged transit times (mean delay 6.1 seconds, signal intensity >70%), these regions progressed to infarction in all except 1 patient, but infarct expansion was underestimated (P<0.001). CONCLUSIONS: The acute rCBF lesion most accurately identified tissue in the PWI>DWI mismatch region at risk of infarction. Color-thresholded PWI maps show potential for use in an acute clinical setting to prospectively predict tissue outcome.

Acute Disease↗
PubMed2001

The value of apparent diffusion coefficient maps in early cerebral ischemia.

BACKGROUND AND PURPOSE: Prediction of the regions of the ischemic penumbra that are likely to progress to infarction is of great clinical interest. Whether lowered apparent diffusion coefficient (ADC) values were present in the ischemic penumbra of patients presenting with acute ischemic stroke and were specific to regions of the penumbra that proceeded to infarction was investigated. METHODS: Nineteen patients with hemispheric stroke of less than 6 hours' onset and with acute scans showing a perfusion lesion greater than a diffusion lesion (ischemic penumbra) were studied. Scans also were performed subacutely (days 3 to 5) and at outcome (day 90). The outcome scan was used to identify regions of the penumbra that proceeded to infarction. RESULTS: The ADC ratios were significantly reduced (P <.00001) in regions of the penumbra that progressed to infarction on the outcome scan compared with those that remained normal. In regions that showed transition to infarction, the mean ADC ratios were typically 0.75 to 0.90. CONCLUSION: Intermediate ADC values are present in the ischemic penumbra and are indicative of tissue at risk of infarction.

Aged↗
PubMed2000

Combined (1)H MR spectroscopy and diffusion-weighted MRI improves the prediction of stroke outcome.

BACKGROUND: The prognostic value of the biochemical changes seen with proton MR spectroscopy (1H MRS) in ischemic stroke was examined. Acute diffusion-weighted imaging (DWI) was used to identify regions of ischemia for 1H MRS voxel localization. METHODS: Nineteen patients had 36 1H MRS studies, 13 patients acutely (mean, 11.1 hours), 10 subacutely (mean, 3.9 days), and 13 at outcome (mean, 82 days). Single-voxel, long-echo, timepoint-resolved spectroscopy was used to obtain lactate, n-acetylaspartate (NAA), choline, and creatine levels from the infarct core. Outcome measures were final infarct volume and clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale). RESULTS: Acute lactate/choline ratio correlated more strongly with clinical outcome scores (r = 0.76 to 0.83; p < 0.01) and final infarct size (r = 0. 96; p < 0.01) than acute DWI lesion volume or acute NAA/choline ratio. Combination of acute lactate/choline ratio with acute DWI lesion volume improved prediction of all outcome scores (R2 = 0.80 to 0.90). The predictive effect of acute lactate/choline ratio was independent of acute DWI lesion volume (p < 0.001). In subacute and chronic infarction, both lactate/choline and NAA/choline ratios continued to correlate with outcome (p < 0.05). At the chronic stage, persistent lactate/choline ratio elevation strongly correlated with outcome measures (r = 0.71 to 0.87). CONCLUSION: Lactate/choline ratio measured in the acute infarct core by 1H MRS improves the prediction of stroke outcome and provides prognostic information complementary to DWI. Lactate/choline ratio could be used as an additional marker to select patients for acute and chronic therapies.

Aged↗
PubMed1999

Absent middle cerebral artery flow predicts the presence and evolution of the ischemic penumbra.

OBJECTIVES: In acute ischemic stroke the pattern of a perfusion-imaging (PI) lesion larger than the diffusion-weighted imaging (DWI) lesion may be a marker of the ischemic penumbra. We hypothesized that acute middle cerebral artery (MCA) occlusion would predict the presence of presumed "penumbral" patterns (PI > DWI), ischemic core evolution, and stroke outcome. METHODS: Echoplanar PI, DWI, and magnetic resonance angiography (MRA) were performed in 26 patients with MCA territory stroke. Imaging and clinical studies (Canadian Neurological Scale, Barthel Index, and Rankin Scale) were performed within 24 hours of onset and repeated at days 4 and 90. RESULTS: MCA flow was absent in 9 of 26 patients. This was associated with larger acute PI and DWI lesions, greater PI/DWI mismatch, early DWI lesion expansion, larger final infarct size, worse clinical outcome (p < 0.01) and provided independent prognostic information (multiple linear regression analysis, p < 0.05). Acute penumbral patterns were present in 14 of 26 patients. Most of these patients (9 of 14) had no MCA flow, whereas all nonpenumbral patients (PI < or = DWI lesion) had MCA flow (p < 0.001). Penumbral-pattern patients with absent MCA flow had greater DWI lesion expansion (p < 0.05) and worse clinical outcome (Rankin Scale score, p < 0.05). CONCLUSIONS: Absent MCA flow on MRA predicts the presence of a presumed penumbral pattern on acute PI and DWI and worse stroke outcome. Combined MRA, PI, and DWI can identify individual patients at risk of ischemic core progression and the potential to respond to thrombolytic therapy beyond 3 hours.

Adult↗
PubMed1999

Correlation of ultrasound and magnetic resonance imaging with clinical outcome after patellar tenotomy: prospective and retrospective studies. Victorian Institute of Sport Tendon Study Group.

OBJECTIVE: To report the appearances of ultrasound (US) and magnetic resonance imaging (MRI) before and after surgery for chronic patellar tendinopathy and to correlate postoperative appearances with clinical outcome. DESIGN: A 12-month prospective longitudinal study and a retrospective study, each part using different patients. Prospective study included clinical assessment, ultrasound, and MRI all performed before and 12 months after surgery. Retrospective study included ultrasound and clinical assessment only (i.e., no MRI) 24 to 67 months after surgery. SETTING: Institutional athlete study group in Australia (Victorian Institute of Sport Tendon Study Group). PATIENTS: In the prospective study, 13 patients (all male; 15 tendons) who underwent patellar tenotomy; in the retrospective study, 17 different patients (18 tendons) who had undergone identical surgery. MAIN OUTCOME MEASURES: Ultrasound and MRI appearances and clinical assessment at baseline and 12 months after surgery (prospective study). Ultrasound appearance and clinical assessment 24 to 67 months after surgery (retrospective study). Dimensions of abnormal regions on imaging were measured. Clinical assessment included categorical rating and numerical Victorian Institute of Sport Assessment (VISA) score. RESULTS: In the prospective study, preoperative ultrasound and MRI appearances confirmed the clinical diagnosis of patellar tendinopathy. Postoperative ultrasound and MRI also revealed abnormalities consistent with patellar tendinopathy. Despite this, 11 of 15 (73%) tendons were rated clinically as either good or excellent. Imaging modalities were unable to distinguish tendons rated as good or excellent from those rated poor at 12 months. In the retrospective study, ultrasound images revealed abnormalities despite full clinical recovery. There was no correlation between dimension of ultrasound abnormality and either VISA score or time since surgery. CONCLUSION: After open patellar tenotomy, MRI and ultrasound findings remain abnormal despite clinical recovery. Thus, clinicians ought to base postoperative management of patients undergoing patellar tenotomy on clinical grounds rather than imaging findings. At present, there appears to be no role for routine postoperative imaging of patients recovering slowly after patellar tenotomy. However, this is not to suggest that imaging cannot play a role in special circumstances.

Adolescent↗
PubMed1999

Pathophysiological topography of acute ischemia by combined diffusion-weighted and perfusion MRI.

BACKGROUND AND PURPOSE: Combined echoplanar MRI diffusion-weighted imaging (DWI), perfusion imaging (PI), and magnetic resonance angiography (MRA) can be used to visualize acute brain ischemia and predict lesion evolution and functional outcome. The appearance of a larger lesion by PI than by DWI quantitatively defines a mismatch of potential clinical importance. Qualitative lesion variations exist in the topographic concordance of this mismatch. We examined both the topographic heterogeneity and relative frequency of mismatched patterns in acute stroke using these MRI techniques. METHODS: Acute DWI, PI, and MRA studies of 34 prospectively recruited patients with supratentorial ischemic lesions scanned within 24 hours of stroke onset (range 2.5 to 23.3 hours, 12 patients <6 hours) were analyzed. RESULTS: Ischemic lesions were predominantly in the middle cerebral artery (MCA) territory (94%), with DWI lesions most commonly affecting the insular region. Mismatched patterns with PI lesion larger than DWI lesion occurred in 21 patients (62% overall), in all 4 patients imaged within 3 hours, and in 44% of patients imaged after 18 hours. A patient with a large PI but no DWI lesion and severe clinical deficit at 2.5 hours after stroke onset recovered completely. Regional variations in DWI and PI lesion loci were found, inferring site of proximal MCA occlusion, embolic pathogenesis, and regional arterial reperfusion. CONCLUSIONS: Analysis of the topographic concordance of PI and DWI lesions in acute stroke reveals regional PI lesions without concomitant DWI lesions, which do not necessarily progress to infarction but may suggest stroke pathogenesis and site of current arterial occlusion. Location of DWI lesions may suggest an earlier site of arterial occlusion and regions of maximal perfusion deficit.

Aged↗
PubMed1999

Identification of major ischemic change. Diffusion-weighted imaging versus computed tomography.

BACKGROUND AND PURPOSE: Thrombolytic therapy is not recommended in patients with CT changes of recent major infarction, which has been defined as reduced attenuation or cerebral edema involving >33% of the middle cerebral artery territory (European Cooperative Acute Stroke Study [ECASS] criteria). Diffusion-weighted imaging (DWI) is more sensitive than CT in detecting acute ischemia, and the combination of DWI, MR perfusion imaging, and MR angiography provides additional information from a single examination. We sought to determine whether DWI could identify the presence and extent of major ischemia as well as CT in hyperacute stroke patients. METHODS: Seventeen suspected hemispheric stroke patients were studied with both CT and DWI within 6 hours of symptom onset. None received thrombolytic therapy. The scans were examined separately by 2 neuroradiologists in a blinded fashion for ischemic change and cerebral edema, graded as normal, <33%, or >33% of the MCA territory. Final diagnosis of stroke was determined with the use of standard clinical criteria and T2-weighted imaging at day 90. RESULTS: Sixteen of 17 patients had a final diagnosis of stroke. Acute ischemic changes were seen in all 16 on DWI (100% sensitivity) and in 12 of 16 on CT (75% sensitivity). DWI identified all 6 patients with major ischemia on CT, with excellent agreement between the 2 imaging techniques (kappa=0.88). One patient eligible for thrombolysis on the ECASS CT criteria had major ischemia on DWI. CONCLUSIONS: DWI is more sensitive than CT in the identification of acute ischemia and can visualize major ischemia more easily than CT.

Adult↗
PubMed1999

Serial study of apparent diffusion coefficient and anisotropy in patients with acute stroke.

BACKGROUND AND PURPOSE: We sought to characterize the evolution of apparent diffusion coefficient (ADC) and apparent diffusion anisotropy (ADA) in acute stroke and to evaluate their roles in predicting stroke evolution and outcome. METHODS: We studied 26 stroke patients acutely (<24 hours), subacutely (3 to 5 days), and at outcome (3 months). Ratios of the ADC and ADA within a region of infarction and the normal contralateral region were evaluated and compared with the Canadian Neurological Scale, Barthel Index, and Rankin Scale. RESULTS: Heterogeneity in ADC and ADA evolution was observed not only between patients but also within individual lesions. Three patterns of ADA evolution were observed: (1) elevated ADA acutely and subacutely; (2) elevated ADA acutely and reduced ADA subacutely; and (3) reduced ADA acutely and subacutely. At outcome, reduced ADA with elevated ADC was observed generally. We identified 3 phases of diffusion abnormalities: (1) reduced ADC and elevated ADA; (2) reduced ADC and reduced ADA; and (3) elevated ADC and reduced ADA. The ADA ratios within 12 hours correlated with the acute Canadian Neurological Scale (r=0.46, P=0.06), subacute Canadian Neurological Scale (r=0.55, P=0.02), outcome Barthel Index (r=0.62, P=0.01), and Rankin Scale (r=-0.77, P<0.0005) scores. CONCLUSIONS: Combined ADC and ADA provide differential patterns of stroke evolution. Early ADA changes reflect cellular alterations in acute ischemia and may provide a potential marker to predict stroke outcome.

Acute Disease↗
PubMed1998

Prediction of stroke outcome with echoplanar perfusion- and diffusion-weighted MRI.

OBJECTIVES: We examined the utility of echoplanar magnetic resonance perfusion imaging and diffusion-weighted imaging (DWI) in predicting stroke evolution and outcome in 18 patients with acute hemispheric infarction. METHODS: Patients were studied within 24 hours (mean, 12.2 hours), subacutely (mean, 4.7 days), and at outcome (mean, 84 days). Comparisons were made between infarction volumes as measured on perfusion imaging (PI) and isotropic DWI maps, clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale), and final infarct volume (T2-weighted MRI). RESULTS: Acute PI lesion volumes correlated with acute neurologic state, clinical outcome, and final infarct volume. Acute DWI lesions correlated less robustly with acute neurologic state, but correlated well with clinical outcome and final infarct volume. Three of six possible patterns of abnormalities were seen: PI lesion larger than DWI lesion (65%), PI lesion smaller than DWI lesion (12%), and DWI lesion but no PI lesion (23%). A pattern of a PI lesion larger than the DWI lesion predicted DWI expansion into surrounding hypoperfused tissue (p < 0.05). In the other two patterns, DWI lesions did not enlarge, suggesting that no significant increase in ischemic lesion size occurs in the absence of a larger perfusion deficit. CONCLUSIONS: Combined early PI and DWI can define different acute infarct patterns, which may allow the selection of rational therapeutic strategies based on the presence or absence of potentially salvageable ischemic tissue.

Adult↗
PubMed1997

Perfusion patterns in postictal 99mTc-HMPAO SPECT after coregistration with MRI in patients with mesial temporal lobe epilepsy.

OBJECTIVES: To assess patterns of postictal cerebral blood flow in the mesial temporal lobe by coregistration of postictal 99mTc-HMPAO SPECT with MRI in patients with confirmed mesial temporal lobe epilepsy. METHODS: Ten postictal and interictal 99mTc-HMPAO SPECT scans were coregistered with MRI in 10 patients with confirmed mesial temporal lobe epilepsy. Volumetric tracings of the hippocampus and amygdala from the MRI were superimposed on the postictal and interictal SPECT. Asymmetries in hippocampal and amygdala SPECT signal were then calculated using the equation: % Asymmetry =100 x (right - left) / (right + left)/2. RESULTS: In the postictal studies, quantitative measurements of amygdala SPECT intensities were greatest on the side of seizure onset in all cases, with an average % asymmetry of 11.1, range 5.2-21.9. Hippocampal intensities were greatest on the side of seizure onset in six studies, with an average % asymmetry of 9.6, range 4.7-12.0. In four scans the hippocampal intensities were less on the side of seizure onset, with an average % asymmetry of 10.2, range 5.7-15.5. There was no localising quantitative pattern in interictal studies. CONCLUSIONS: Postictal SPECT shows distinctive perfusion patterns when coregistered with MRI, which assist in lateralisation of temporal lobe seizures. Hyperperfusion in the region of the amygdala is more consistently lateralising than hyperperfusion in the region of the hippocampus in postictal studies.

Amygdala↗
PubMed1996

Reduction of length of stay and cost of transurethral resection of the prostate by early catheter removal.

OBJECTIVE: To determine whether early removal of the indwelling Foley catheter after transurethral resection of the prostate (TURP) significantly shortens the hospital stay without causing additional morbidity and thus saves costs. PATIENTS AND METHODS: For the year commencing 1 July 1991, 119 patients who had undergone TURP had their indwelling catheter removed on the first day after surgery. The results and morbidity of this group of patients were compared with those in 152 patients undergoing TURP during the previous year. The economic consequences of this protocol were calculated using both Medicare and CHAMPUS data. RESULTS: The demographics of the patients in both groups were similar. Post-operative complications occurred in 5% of the study patients and in 6.6% of controls; a transfusion was required in 2.5% and 1.3%, clot retention developed in 1.7% and 3.3% and the hospital stay was reduced from 3.1 to 1.28 days in the study and control patients, respectively. Using Medicare data, the mean cost saving of early catheter removal would be $829 and $1406 for patients aged < 70 and > 70 years, respectively. For CHAMPUS patients, the cost saving would be $1983. CONCLUSION: Early removal of the catheter after TURP did not increase morbidity and maintained the efficacy of the procedure. If this practice was adopted nationally, the savings resulting from the reduction in hospital stay would be considerable.

Aged↗
PubMed1996

Patellar tendinosis (jumper's knee): findings at histopathologic examination, US, and MR imaging. Victorian Institute of Sport Tendon Study Group.

PURPOSE: To determine the histopathologic findings of patellar tendinosis ("jumper's knee") demonstrated with ultrasonography (US) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: Twenty-four athletes (28 knees) with jumper's knee (23 men, one women; mean age, 30.9 years) scheduled to undergo open tenotomy underwent US patellar tendon examination. Seventeen patients (19 knees) also underwent MR imaging. Tissue was obtained for histopathologic examination in all 28 cases. Eleven age-, height-, and weight-matched athletes (22 knees) without previous knee symptoms served as control subjects for the US examination. Control material for histopathologic examination was obtained in 20 cadavers (39 knees). Data were analyzed with standard statistical methods. RESULTS: MR imaging and US both revealed an abnormal zone at the proximal patellar tendon attachment. Histopathologic examination revealed mucoid degeneration in all tendons in patients and in 8% (three of 39) of tendons in cadavers (P < .01). CONCLUSION: Jumper's knee is characterized by consistent changes at MR imaging, US, and histopathologic examination and is appropriately described as patellar tendinosis.

Adult↗
PubMed1995

Febrile seizures and hippocampal sclerosis: frequent and related findings in intractable temporal lobe epilepsy of childhood.

The relationship between hippocampal sclerosis, febrile seizures, and complex partial seizures in temporal lobe epilepsy continues to be the subject of great debate in the literature. Hippocampal sclerosis is reported infrequently in young children with temporal lobe epilepsy, a factor that has supported the theory that hippocampal sclerosis develops in later life during the course of recurrent complex partial seizures. In a blinded review of magnetic resonance imaging in 53 children, aged 2-17 years (mean: 10 years) with temporal lobe epilepsy, hippocampal sclerosis was diagnosed in 30 children (57%), concordant with ictal electroencephalographic lateralization in 93% and pathologic diagnosis in all children who had undergone surgery and had hippocampal tissue available for histologic examination. Fourteen of the children (47%) with hippocampal sclerosis were younger than 10 years of age, the youngest being 2 years. Thirty-four children (64%) had histories of neurologic insults prior to the onset of complex partial seizures, including idiopathic febrile seizures in 22. Hippocampal sclerosis was associated with a history of a neurologic insult prior to the onset of complex partial seizures (P < .001) and was not associated with age at onset of temporal lobe epilepsy, age at magnetic resonance imaging, duration of epilepsy, or presence of secondarily generalized seizures. These findings suggest that hippocampal sclerosis is underdiagnosed in children and is the cause and not the consequence of temporal lobe epilepsy.

Adolescent↗
PubMed1995

Balloon dilation of the prostate: correlation with magnetic resonance imaging and transrectal ultrasound findings.

Alternative treatments for benign prostatic hyperplasia are under intense scrutiny. Initial reports on balloon dilation therapy showed success rates of 60% to 90%, although follow-up was brief. We present a prospective non-blinded study assessing the efficacy of an investigational balloon dilatation catheter (105 Fr at 3 atm) as well as the MRI findings preoperatively and postoperatively. Twenty-seven men underwent balloon dilation and have been followed for at least 1 year. Twelve patients (44%) ultimately required definitive transurethral prostatectomy during follow-up. A mild improvement was noted in the symptom score and flow rate in the responder group. Fracture of the anterior commissure was accomplished in only 5 patients (18%) despite diligent efforts. The MRI scans showed no change in the prostate in any patients. Intraoperative transrectal ultrasound scanning suggested that proximal balloon migration can occur. Our experience with this balloon system leads us to recommend that it remain an investigational procedure.

Aged↗