Significant Perfusion Abnormalities Research Articles

P-Wave Terminal Force V1 Is Associated with Left Ventricular Diastolic Function in Patients with No Significant Perfusion Abnormality.

P-wave terminal force in lead V1 (PTFV1) is a marker of increased left atrial (LA) overload. Whether PTFV1 is associated with left ventricular (LV) diastolic function remains undetermined. We tested the hypothesis that PTFV1 is associated with LV diastolic parameters derived from gated myocardial perfusion single-photon emission computed tomography (SPECT) in patients with no significant perfusion abnormalities.The study population included 158 patients with preserved ejection fraction and no significant perfusion abnormalities. The amplitude and duration of the P-wave negative phase in lead V1 were measured using an electrocardiogram, and PTFV1 was calculated. The peak filling rate (PFR) and one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters using gated SPECT.PTFV1 showed a weak correlation with the LA volume index (r = 0.31; P < 0.001). Significant associations were observed between PTFV1 and PFR (r = -0.27; P < 0.001) and 1/3 MFR (r = -0.26; P = 0.001). A multivariate linear regression analysis showed that age (β = -0.26; P < 0.001), LV end-diastolic volume index (β = -0.27; P = 0.001), and PTFV1 (β = -0.15; P = 0.036) were significant factors associated with PFR. Moreover, male gender (β = -0.16; P = 0.041), LV mass index (β = -0.17; P = 0.046), and PTFV1 (β = -0.17; P = 0.022) were significant factors associated with the 1/3 MFR.PTFV1 is associated with LV diastolic function, as derived from gated SPECT in patients with no significant perfusion abnormalities.

Comparative Analysis of the Diagnostic Effectiveness of SATRO ECG in the Diagnosis of Ischemia Diagnosed in Myocardial Perfusion Scintigraphy Performed Using the SPECT Method.

There is a great need for early diagnosis of ischemic heart disease (IHD), the most common cause of which is haemodynamic disorders caused mainly by obstructive atherosclerosis of the coronary arteries. The diagnosis of IHD is usually made with the use of functional tests, which include resting ECG (R) or examination of significant perfusion disorders during exercise using the SPECT method. Despite the fact that the ECG (R) test is commonly used in cardiological diagnostics, it has a limited diagnostic value, especially in people with a low probability of coronary artery disease (CAD). In order to increase the effectiveness of the ECG (R) examination, SATRO ECG software, based on the single fibres heart activity model (SFHAM), was used to evaluate the electrocardiograms. The introduction of new classifiers from the available medical data to the analysis made it possible to evaluate the diagnostic efficacy of SATRO ECG (TOT) in predicting significant perfusion disorders in the exercise SPECT (TOT 2). These disorders are most often caused by obstructive atherosclerosis of the coronary arteries, which is the main cause of CAD. The database of 316 patients (219 men and 97 women, aged 57 ± 10 years) was analyzed using resting and stress ECG, perfusion scintigraphy performed using the SPECT method, and SATRO ECG analysis. The diagnostic efficacy parameters of SATRO ECG (TOT) in predicting significant perfusion abnormalities in the exercise-induced SPECT (TOT 2) study were: sensitivity, 99%; specificity, 91%; concordance, 96%; and positive, 96%, and negative, 97%, predictive values. The Kappa–Cohen coefficient was 0.92, and the statistical significance coefficient was p < 0.001. These results indicate a statistically significant agreement in the diagnosis of IHD in both diagnostic methods used.

Arterial spin labeling for presurgical localization of refractory frontal lobe epilepsy in children

BackgroundEpilepsy is one of the most common chronic neurological diseases. Despite the great variety and prevalence of antiepileptic drug treatments, one-third of epilepsies remain drug resistant. The frontal lobe is extensive, and frontal lobe seizures are difficult to locate, which increases the difficulty of the preoperative localization of the epileptogenic zone.Case presentationTwo previously healthy girls with refractory frontal lobe epilepsy showed significant perfusion abnormalities in the right frontal lobe using the cerebral blood perfusion (CBF) quantitative analysis system. They became seizure-free after lesionectomy of the frontal lobe by ASL combined with electroencephalography (EEG) rapid localization. The histopathological diagnosis was focal cortical dysplasia (FCD) type IIa and IIb.ConclusionsThe positive outcome suggests that the combined use of ASL with EEG could be a beneficial option for the presurgical evaluation of pediatric epilepsy.

The Monocyte to High-Density Lipoprotein Cholesterol Ratio Is Associated with Left Ventricular Diastolic Function in Patients with No Significant Perfusion Abnormality.

The monocyte to high-density lipoprotein cholesterol (HDL-C) ratio has been considered to be a prognostic marker. Whether this ratio is associated with left ventricular (LV) diastolic function remains undetermined. We tested the hypothesis that the monocyte to HDL-C ratio is associated with LV diastolic parameters derived from gated myocardial perfusion single-photon emission computed tomography (SPECT) in patients with no significant perfusion abnormality.The study population included 196 patients with no significant perfusion abnormalities and preserved ejection fraction. The peak filling rate (PFR) and one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters using gated SPECT. Monocyte counts and plasma HDL-C levels were also examined.Significant associations were observed between the monocyte to HDL-C ratio and PFR (r = -0.20; P = 0.005) and 1/3 MFR (r = -0.19; P = 0.009). Multivariate linear regression analysis was performed to determine factors associated with LV diastolic parameters. Age (β = -0.27; P < 0.001), LV end-diastolic volume (β = -0.19; P = 0.034), and monocyte to HDL-C ratio (β = -0.15; P = 0.027) were determined to be significantly associated with PFR. Moreover, age (β = -0.13; P = 0.007), LV mass index (β = -0.18; P = 0.037), and the monocyte to HDL-C ratio (β = -0.13; P = 0.045) were significantly associated with 1/3 MFR.These results demonstrated that the monocyte to HDL-C ratio is associated with LV diastolic function, as derived from gated SPECT in patients with no significant perfusion abnormality.

Frontal QRS-T angle and left ventricular diastolic function assessed by ECG-gated SPECT in the absence of significant perfusion abnormality.

The frontal QRS-T angle, defined as the angle between QRS and T-wave axes, has recently become an area of research interest. We tested the hypothesis that the frontal QRS-T angle is associated with left ventricular (LV) diastolic function in the absence of significant perfusion abnormality using ECG-gated SPECT. One hundred twenty eight patients with no significant perfusion abnormality and preserved LV ejection fraction were enrolled. The peak filling rate (PFR) and the one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters on ECG-gated SPECT. There were 115 male and 13 female patients with a mean age of 70 ± 9years. The PFR and 1/3 MFR were 2.1 ± 0.4/s and 1.2 ± 0.3/s, respectively. The frontal QRS-T angle was 33° ± 31°, ranging from 0° to 151°. There were significant associations of frontal QRS-T angle with PFR (r = -0.29, p = 0.001) and 1/3 MFR (r = -0.30, p < 0.001). Multivariate linear regression analysis showed that age (β = -0.25, p = 0.003), heart rate (β = 0.26, p = 0.002), LV ejection fraction (β = 0.43, p < 0.001) and frontal QRS-T angle (β = -0.16, p = 0.03) were significant factors associated with PFR. Also, heart rate (β = -0.32, p < 0.001), LV mass index (β = -0.19, p = 0.03), LV ejection fraction (β = 0.30, p < 0.001) and frontal QRS-T angle (β = -0.26, p = 0.002) were significant factors associated with 1/3 MFR. Our data suggested that the frontal QRS-T angle was associated with LV diastolic function in the absence of significant perfusion abnormality.

Associations of left ventricular shape with left ventricular volumes and functions assessed by ECG-gated SPECT in patients without significant perfusion abnormality.

Left ventricular (LV) remodeling often results from conditions with an elevated LV hemodynamic load or after myocardial infarction. The present study was undertaken to investigate the associations of LV shape with LV volumes and functions in patients without significant perfusion abnormality. One hundred and sixty-seven patients without significant perfusion abnormality on ECG-gated SPECT were enrolled. LV ejection fraction (LVEF) was obtained for assessing LV systolic function. Peak filling rate (PFR) and one-third mean filling rate (1/3 MFR) were obtained for assessing LV diastolic function. LV shape index (LVSI) was defined as the ratio of the maximum three-dimensional short- and long-axis LV dimension, and varies from 0 (line) to 1 (sphere). There were 125 male and 42 female patients with a mean age of 70 ± 8years. End-systolic LVSI was 0.49 ± 0.07 (0.34-0.65). End-systolic LVSI was associated with LV end-diastolic volume (r = 0.51, p < 0.001) and LV end-systolic volume (LVESV) (r = 0.64, p < 0.001), and was inversely associated with LVEF (r = -0.69, p < 0.001), PFR (r = -0.45, p < 0.001) and 1/3 MFR (r = -0.26, p = 0.008). End-systolic LVSI was increased with increased LVESV, and was not any more with LVESV of > 40ml. Multivariate liner regression analysis showed that age (β = 0.16, p = 0.01), LVESV (β = 0.20, p = 0.03) and LVEF (β = -0.53, p < 0.001) were significantly associated with end-systolic LVSI. Our data suggest that end-systolic LVSI, a measurement of LV shape, has close correlations with LV volumes and functions in patients without significant perfusion abnormality.

The diagnostic efficacy and safety of stress-only supine and prone myocardial perfusion imaging with a dedicated cardiac gamma camera in patients with suspected or known coronary artery disease.

Myocardial perfusion scintigraphy remains one of the substantial noninvasive diagnostic methods in coronary artery disease. Recent technological advancement allowed to create novel semiconductor, dedicated cardiac gamma camera with better spatial resolution and higher energy resolution, resulting in the reduction of radiation burden and acquisition time. The aim of this study was to evaluate the efficacy and safety of stress-only supine and prone MPS with a cardiac gamma camera in patients with suspected or known coronary artery disease. A total number of 203 consecutive patients with suspected or known coronary artery disease, who underwent MPS were enrolled in the study. The patients without perfusion abnormalities on stress supine and prone MPS scans had no rest MPS, in the remaining patients two-day stress-rest imaging was performed. The group of 160 patients with one-year follow up was subjected to final analysis. Stress-only protocol of myocardial perfusion imaging was performed in 72 patients, 88 patients underwent two-day stress and rest myocardial perfusion scintigraphy. In 46 out of 72 stress-only group of patients, prone study did not affect further proceedings. However, in over 1/3 of cases (26/72), prone scans resulted in abstaining from rest imaging. One year follow-up revealed no sudden cardiac deaths or myocardial infarctions in both (stress-only and stress-rest) groups. Revascularization was performed most often in the double-positive group - patients with significant ischaemia on myocardial perfusion images and chest pain or electrocardiographic changes or both during the stress test. In this double-positive group, all 11 patients had coronary angiography (two of them prior to myocardial perfusion scintigraphy), nine of them had subsequent revascularization. In patients with no significant perfusion abnormalities on stress scans omitting rest study is safe with very good one-year risk prognosis of acute cardiac events and allows to limit the radiation exposure and procedure duration. Additional prone acquisitions are valuable supplements in determining the decision of safe early completion of myocardial perfusion imaging.

Interactions Between Reciprocal ST-Segment Downsloping During ST-Elevated Myocardial Infarction and Global Cardiac Perfusion and Functional Abnormalities

Reciprocal ST-segment downsloping on electrocardiogram is a frequent finding during ST-elevated myocardial infarction (STEMI), but its etiology is still disputed. We sought to evaluate the relation between reciprocal ST-segment downsloping during STEMI and major cardiac perfusion and functional parameters. One hundred eighty-five patients with STEMI underwent emergency coronary angiography. The presence of reciprocal ST-segment downsloping was assessed. At coronary angiography, the corrected TIMI frame count (cTFC) was computed both on culprit and remote vessels and the occurrence of "no/slow reflow" phenomenon after percutaneous coronary intervention (PCI) identified. The left ventricular wall motion score index ratio (discharge/admission values) at echocardiography and the slope of high-sensitivity troponin elimination were computed as measures of effective myocardial reperfusion. Reciprocal ST-segment downsloping was revealed in 91 patients (49%). They presented higher cTFC values on remote vessels than patients without reciprocal electrocardiographic abnormalities (44 ± 18 vs 37 ± 15 cineframes× second-1, p= 0.004). The presence of remote ST-segment downsloping was also associated with a higher prevalence of "no/slow reflow" phenomenon (59% vs 40%, p=0.013) as well as more abnormal values of wall motion score index ratio (p= 0.042) and high-sensitivity troponin slope (p=0.012). At multivariate analyses, a higher cTFC on remote vessels predicted the occurrence of reciprocal ST-segment changes (p= 0.018) and the development of "no/slow reflow" phenomenon after PCI (p= 0.005). In conclusion, the presence of reciprocal ST-segment downsloping during STEMI clusters with significant perfusion and cardiac functional abnormalities, predicting the development of "no reflow" phenomenon after PCI.

Brain Perfusion and Diffusion Abnormalities in Children Treated for Posterior Fossa Brain Tumors

To compare cerebral perfusion and diffusion in survivors of childhood posterior fossa brain tumor with neurologically normal controls and correlate differences with cognitive dysfunction. We analyzed retrospectively arterial spin-labeled cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) in 21 patients with medulloblastoma (MB), 18 patients with pilocytic astrocytoma (PA), and 64 neurologically normal children. We generated ANCOVA models to evaluate treatment effects on the cerebral cortex, thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens, and cerebral white matter at time points an average of 5.7 years after original diagnosis. A retrospective review of patient charts identified 12 patients with neurocognitive data and in whom the relationship between IQ and magnetic resonance imaging variables was assessed for each brain structure. Patients with MB (all treated with surgery, chemotherapy, and radiation) had significantly lower global CBF relative to controls (10%-23% lower, varying by anatomic region, all adjusted P?<?.05), whereas patients with PA (all treated with surgery alone) had normal CBF. ADC was decreased specifically in the hippocampus and amygdala of patients with MB and within the amygdala of patients with PA but otherwise remained normal after therapy. In the patients with tumor previously evaluated for IQ, regional ADC, but not CBF, correlated with IQ (R2?=?0.33-0.75). The treatment for MB, but not PA, was associated with globally reduced CBF. Treatment in both tumor types was associated with diffusion abnormalities of the mesial temporal lobe structures. Despite significant perfusion abnormalities in patients with MB, diffusion, but not perfusion, correlated with cognitive outcomes.

Rapid-acquisition myocardial perfusion scintigraphy (MPS) on a novel gamma camera using multipinhole collimation and miniaturized cadmium-zinc-telluride (CZT) detectors: prognostic value and diagnostic accuracy in a 'real-world' nuclear cardiology service

To study the prognostic value of rapid-acquisition adenosine stress-rest myocardial perfusion scintigraphy (MPS) on a gamma camera using multipinhole collimation and cadmium-zinc-telluride (CZT) detectors. The secondary aim was to assess the diagnostic accuracy of the technique compared with invasive coronary angiography. Retrospective analysis of 1109 consecutive patients undergoing MPS in a routine clinical setting on a high-efficiency multipinhole gamma camera. MPS acquisition, performed with a standard injection of 550 MBq of (99m)Tc-tetrofosmin, required a mean (±SD) scanning time of 322 ± 51 s. The hard cardiac event rate at a median (inter-quartile range) follow-up of 624 (552-699) days was 0.4% (95% CI 0.1-1.1) in patients with no significant perfusion abnormality versus 6.8% (95% CI 4.3-10.7%, P < 0.001) in those with an abnormal scan. In a sub-group of 165 patients, comparison with obstructive coronary artery disease on X-ray angiography gave a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for rapid-acquisition MPS of 84% (95% CI 74-91), 79% (95% CI 68-87), 82% (95% CI 72-89), 81% (95% CI 70-89), and 82% (95% CI 73-89), respectively. MPS performed on a CZT solid-state detector camera with multipinhole collimation is an evolutionary development that provides reliable prognostic and diagnostic information, while significantly reducing image acquisition time.

Normal or near normal myocardial perfusion stress imaging in patients with severe coronary artery disease

Normal or near normal myocardial perfusion stress imaging (MPI) suggests the absence of life-threatening coronary artery disease (CAD). Nevertheless, there are instances where severe left main or three-vessel CAD may be present despite no significant perfusion abnormalities on MPI. Review of Tl-201 or Tc-99m sestamibi MPI over a period of 5 years to ascertain the features that may prevent misdiagnosis. Out of 9171 tests, 3992 (44%) were interpreted as normal or near normal. For clinical reasons, 98 (2%) of these patients underwent coronary angiography within 6 months. A total of 3992 patients were interpreted as normal or near normal. Seventy (22 men/48 women; 58 +/- 13 years) did not have obstructive CAD. Nine (six men/three women; 64 +/- 8 years) had either left main (n = 3), three-vessel CAD with or without left main (n = 3) or severe proximal left anterior descending (n = 3) disease. Although both normal patients and patients with CAD had similar proportions of imaging artifacts, those with severe CAD had significantly more markers of CAD (increased lung Tl-201 uptake, transient ischemic cavity dilatation, stress-induced ST-segment depression, chest pain, and/or hypotension with exercise; P < 0.01; no CAD vs. severe CAD; two-tail Fisher's Exact Test). Similarly, patients with moderate CAD by coronary angiography (n = 19), and a random sample of 250 patients (82 men/168 women; 62 +/- 14 years) with normal or near normal MPI who did not undergo coronary angiography, had similar proportions of imaging artifacts but significantly fewer markers of CAD. When dealing with individual patients, the referring physician and the interpreter of MPI studies should consider severe CAD when there are markers of CAD despite normal or near normal perfusion images.

Voxel-by-voxel analysis of brain SPECT perfusion in Fibromyalgia

We evaluated brain perfusion SPECT at rest, without noxious stiumuli, in a homogeneous group of hyperalgesic FM patients. We performed a voxel-based analysis in comparison to a control group, matched for age and gender. Under such conditions, we made the assumption that significant cerebral perfusion abnormalities could be demonstrated, evidencing altered cerebral processing associated with spontaneous pain in FM patients. The secondary objective was to study the reversibility and the prognostic value of such possible perfusion abnormalities under specific treatment. Eighteen hyperalgesic FM women (mean age 48 yr; range 25–63 yr; ACR criteria) and 10 healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 ( p<0.05, corrected for multiple comparisons). All brain SPECT were performed before any change was made in therapy in the pain care unit. A second SPECT was performed a month later after specific treatment by Ketamine. Compared to control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. We also found that a medial frontal and anterior cingulate hypoperfusions were highly predictive (PPV=83%; NPV=91%) of non-response on Ketamine, and that only responders showed significant modification of brain perfusion, after treatment. In the present study performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective dimension. As current pharmacological and non-pharmacological therapies act differently on both components of pain, we hypothesize that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain-processing recovery under treatment.

Perfusion CT and angio CT in the assessment of acute stroke.

In order to evaluate the clinical utility of non-enhanced CT with perfusion and angio CT in the assessment of acute ischaemic stroke, 42 patients with symptoms of acute stroke were examined within the first 6 h from onset of symptoms with non-enhanced CT (NECT), perfusion CT (PCT) and CT angiography (CTA). Maps of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were analysed visually, and after drawing regions of interest (ROIs) in the territory of anterior, middle and posterior cerebral arteries, maximum-intensity projection and volume-rendering images of the cervical and cerebral vessels were created. All patients underwent a control CT or MR examination 24-48 h after the initial examination. Twenty-nine patients developed an area of infarction at control examinations. Significant perfusion abnormalities were found in 27 cases, whilst in two patients the perfusion studies were considered to be normal. All the cases with perfusion abnormalities showed arterial stenoses or occlusions on angio CT. Small infarctions at levels other than the ones selected for perfusion CT, and arteriosclerotic changes, were observed in the two cases with no perfusion abnormalities. In conclusion, combining non-enhanced CT with PCT and CTA is a simple and a very valuable tool in the initial assessment of acute stroke.

The relationship between blood pressure, pulse pressure and right ventricular function following an atrial switch procedure for complete transposition of the great arteries

Background: The pressure overload may be responsible for the failure of the systemic ventricle. No study so far has evaluated the association between arterial blood pressure values and right ventricular function in adults with atrially corrected complete transposition. Methods: This was a retrospective analysis. The studied population consisted of 60 patients with complete transposition, 11.5±2.7 years after atrial switch procedure, divided into subgroups according to the severity of systemic ventricular dysfunction (right ventricular ejection fraction ≤0.40 vs. >0.40), and the severity of perfusion abnormalities in the radionuclide study (absent or mild vs. moderate-to-severe). Results: All patients had blood pressure values (systolic 109.1±11.7 mm Hg and diastolic 72.3±9.7 mm Hg) within the normal range. Systolic blood pressure values correlated inversely with right ventricular ejection fraction ( r=−0.450; p<0.001). Compared to patients with systolic blood pressure below median values, patients with “elevated” blood pressure had lower right ventricular ejection fraction (32.6±6.3 vs. 38.9.±7.2; p≤0.002) and more significant perfusion abnormalities (1.5±1.0 vs. 2.9±1.5; p≤0.001). In a multivariate backward logistic regression model age at surgery and at the time of the study, systolic blood pressure at rest predicted impaired right ventricular ejection fraction ( p<0.02). Greater pulse pressure at peak exercise female sex were associated with greater more severe perfusion abnormalities ( p<0.01). Conclusions: There is a significant correlation between blood pressure values and indices of right ventricular dysfunction in patients who underwent an atrial switch procedure for complete transposition. Blood pressure values might be considered as a surrogate end point in these patients.

Examining the Effect of Cerebral Perfusion Abnormality Magnitude on Cognitive Performance in Recently Abstinent Chronic Cocaine Abusers

Cerebral perfusion abnormalities and neuropsychological impairment are common sequelae of chronic cocaine abuse. While perfusion abnormalities have been shown to relate to cognitive deficits in this substance abuse population, the relationship between cognitive performance and the magnitude of perfusion abnormality has yet to be fully determined. Thirty-seven abstinent cocaine abusers and 13 normal controls were administered resting 99m-Tc-HMPAO single photon emission computed tomography (SPECT) scans followed by a neuropsychological assessment battery tapping executive skills, attention, memory, and motor performance. Statistical parametric mapping (SPM99) techniques were used to analyze the SPECT data to detect significant regional perfusion abnormalities in the cocaine group relative to normal controls, and resulting abnormal SPECT counts were employed for comparison with the assessment measures to examine the relationship between cocaine-induced perfusion abnormalities and cognitive performance. SPECT data analysis revealed significant regional perfusion abnormalities in the cocaine abuse sample relative to controls and significant differences in neuropsychological functioning on measures of executive functioning, complex attention, memory, and manual dexterity. For chronic cocaine abusers, however, within-group comparisons of the magnitude of abnormal perfusion and neuropsychological performance were largely nonsignificant, with the exception of complex attention and motor speed. Perfusion abnormalities and neuropsychological impairments readily distinguished cocaine abusers from normal controls. However, when the magnitude of cocaine-induced perfusion abnormalities is examined in relation to cognitive performance, motor speed and complex attention appear to be the best behaviorial indicants of the severity of perfusion dysfunction within this substance abuse population.

Colloid osmometry

Complications related to intravascular fluid resuscitation and maintenance can become life-threatening. Overhydration and underhydration can lead to significant perfusion abnormalities and can delay or prevent recovery. A working knowledge of transcapillary fluid dynamics gives the veterinarian the basis for evaluating the cause of alterations that make up Starling's forces. By combining this knowledge with patient assessment and laboratory diagnostics, the veterinarian can make a logical decision about the best treatment to correct the Starling's force alteration. Colloid osmometry is a particularly useful tool for assessing a patient's colloid osmotic pressure. It allows the veterinarian to distinguish between reduced oncotic pressure and increased hydrostatic pressure as a cause for intravascular fluid loss or edema formation.

Cerebral Perfusion and Psychometric Testing after exposure to high altitude in the mountains

Exposure to hypobaric hypoxia is known to cause reductions in mental performance and decision-making and it has been reported that these effects are not fully reversed following descent from altitude. Eight climbers had cerebral perfusion scans performed and undertook a battery of psychometric tests prior to, and upon return from, an expedition to climb the eleventh highest mountain in the world, Gasherbrum 1. No decrements were found in either their performance on the psychometric tests nor to their cerebral perfusion following the expedition. Two subjects had significant cerebral perfusion abnormalities prior to the expedition, which had improved immediately following their return from the expedition. Repeat scans four months later showed the lesion of one of the subjects had returned and there were indications that the lesion in the other subject was beginning to return. These findings are in contrast to previous studies which have suggested that altitude exposure leads to permanent reductions in brain function, this could be because in those studies factors other than hypobaric hypoxia per se lead to the reductions in brain function.

Left ventricular long axis disturbances as predictors for thallium perfusion defects in patients with known peripheral vascular disease

ObjectiveTo compare resting long axis echocardiography with adenosine thallium-201 emission tomography in detecting myocardial ischaemic abnormalities in patients before peripheral vascular surgery.DesignA prospective and blinded preoperative examination of resting left...

Prognostic value of thallium-201 perfusion defects in idiopathic dilated cardiomyopathy

To assess the prognostic significance of thallium-201 perfusion defects in patients with idiopathic dilated cardiomyopathy (IDC), 43 patients underwent thallium scintigraphy in addition to clinical, echocardiographic, angiographic and hemodynamic evaluation. Eleven patients had no significant thallium perfusion abnormality, 19 had multiple small defects and 13 had a large defect. During 3.2 ± 2.2 years, 14 patients had disease-related mortality. The patients who died had a higher incidence of ventricular tachycardia (71 vs 31%; p < 0.02), increased cardiothoracic ratio (60 ± 6 vs 54 ± 6%; p = 0.005), decreased fractional shortening (11 ± 6 vs 15 ± 5%; p < 0.05), increased pulmonary wedge pressure (15 ± 7 vs 10 ± 6 mm Hg; p = 0.05), increased left ventricular end-diastolic pressure (21 ± 8 vs 14 ± 6 mm Hg; p = 0.02) and abnormal thallium perfusion defects (13 of 14 vs 16 of 26; p < 0.05) compared with survivors. Age, gender, left ventricular end-systolic and end-diastolic dimensions, cardiac index and ejection fraction were not statistically different in the survivors versus the patients who died. Kaplan-Meier survival estimates at 1, 3 and 5 years were 100% in patients without significant perfusion abnormality; 89, 77 and 64%, respectively, in patients with multiple small defects; and 84, 76 and 30%, respectively, in patients with a large defect (p < 0.025 by log rank test). Stepwise discriminant analysis revealed that the combination of increased cardiothoracic ratio, increased left ventricular end-diastolic pressure, decreased posterior wall thickness and ventricular tachycardia was the best (p = 0.002) predictor of disease-related mortality (sensitivity 91%, specificity 88%, accuracy 89%, positive predictive value 77%). These results indicate that thallium-201 perfusion defects in patients with IDC are associated with a poor prognosis, but do not add to the prognostic value of conventional measurements.

I-123 Hydroxyiodobenzyl Propanediamine (HIPDM) Cerebral Blood Flow Imaging Demonstrating Transtentorial Diaschisis

To assess the clinical significance of transtentorial diaschisis (TTD) as demonstrated by I-123 HIPDM brain imaging, SPECT and/or planar images of 35 patients with stroke, 26 patients with Alzheimer's disease (AD), 2 patients with Creutzfeldt-Jakob disease (CJD), and 1 patient with a schizoaffective disorder were analyzed. TTD was observed in 21 of the 35 patients with strokes. In 13 stroke patients, TTD was associated with large infarcts in the middle cerebral artery (MCA) territory; in the remaining 8 stroke patients, TTD was associated with internal capsule and/or basal ganglia infarcts. TTD was not associated with small occipital or parietal infarcts. Despite cortical perfusion decrements, TTD was not seen in the AD patients, the CJD patients, or the patient with schizoaffective disorder. It is concluded that 1) TTD frequently occurs following cerebral infarct of the MCA territory (60% of the patients in this sample); 2) absence of TTD in the presence of a large cerebral perfusion abnormality may represent neuronal dysfunction of the cerebral cortex; and 3) the presence of TTD without a significant cortical perfusion abnormality may indicate basal ganglia and/or internal capsule infarct.