Abstract: Purpose: This study investigated sequential changes in tumor blood supply using magnetic resonance (MR) perfusion imaging and assessed their significance in the prediction of outcome of patients with advanced cervical cancer The purpose of this project was to devise a simple, noninvasive method to predict early signs of treatment failure in advanced cervical cancer treated with conventional radiation therapy Methods and Materials: Sixty-eight MR perfusion studies were performed prospectively in 17 patients with squamous carcinomas (14) and adenocarcinomas (3) of the cervix, Stages bulky IB (1), IIB (5), IIIA (1), IIIB (8), and IVA (1), and recurrent (1) Four sequential studies were obtained in each patient: immediately before radiation therapy (pretherapy), after a dose of 20–22 Gy/∼2 weeks (early therapy), after a dose of 40–45 Gy/∼4–5 weeks (midtherapy), and 4–6 weeks after completion of therapy (follow-up) Perfusion imaging of the tumor was obtained at 3-s intervals in the sagittal plane A bolus of 01 mmol/kg of MR contrast material (gadoteridol) was injected intravenously 30 s after beginning image acquisition at a rate of 9 ml/s using a power injector Time/signal-intensity curves to reflect the onset, slope, and relative signal intensity (rSI) of contrast enhancement in the tumor region were generated Median follow-up was 8 months (range 3–18 months) Results: Tumors with a higher tissue perfusion (rSI ≥ 28) in the pretherapy and early therapy (20–22 Gy) studies had a lower incidence of local recurrence than those with a rSI of p = 005) An increase in tumor perfusion early during therapy (20–22 Gy), particularly to an rSI of ≥ 28, was the strongest predictor of local recurrence (0% vs 78%; p = 0002) However, pelvic examination during early therapy (20–22 Gy) commonly showed no appreciable tumor regression The slope of the time/signal-intensity curve obtained before and during radiation therapy also correlated with local recurrence Follow-up perfusion studies did not provide information to predict recurrence Conclusion: These preliminary results suggest that two simple MR perfusion studies before and early in therapy can offer important information on treatment outcome within the first 2 weeks of radiation therapy before response is evident by clinical examination Highg tumor perfusion before therapy and increasing or persistent high perfusion early during the course of therapy appear to be favorable signs High perfusion suggests a high blood and oxygen supply to the tumor The increase in tumor perfusion seen in some patients early during radiation therapy suggests improved oxygenation of previously hypoxic cells following early cell kill Radiation tehrapy is more effective in eradicating these tumors, resulting in improved local control Our technique may be helpful in identifying early —while more aggressive therapy can still be implemented—those patients who respond poorly to conventional radiation therapy

Abstract: Objective To describe the rationale, methods, and clinical applications for dobutamine stress echocardiography. Design We review our experience with the first 1,000 Mayo Clinic patients who underwent this procedure and discuss studies from the literature that have assessed the accuracy of dobutamine stress echocardiography in determining the presence and extent of coronary artery disease. Material and Methods The Mayo protocol for dobutamine stress echocardiography is presented, and the indications for use of this test and comparisons of sensitivity and specificity with other tests are summarized. Results Although exercise stress testing is the usual noninvasive method for the detection and assessment of coronary artery disease, a substantial number of patients are unable to perform adequate exercise because of physical limitations. In these patients, dobutamine stress echocardiography has emerged as a feasible, safe, and accurate method for the evaluation of coronary artery disease. The test has been proved to be valuable in the noninvasive diagnosis of coronary artery disease and to have an accuracy comparable to that of tomographic perfusion imaging. Other indications for dobutamine stress echocardiog raphy include risk stratification before noncardiac surgical procedures, risk stratification after myocardial infarction, and identification of viable myocardium in patients with left ventricular dysfunction. Conclusion Dobutamine stress echocardiography is an accurate, safe, cost-effective, and portable procedure for the noninvasive diagnosis of coronary artery disease and for the preoperative assessment of patients with such disease, especially those who are unable to perform adequate exercise tests.

Abstract: We looked for brain perfusion abnormalities in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). An initial pilot study revealed widespread reduction of regional brain perfusion in 24 ME/CFS patients, compared with 24 normal volunteers. Hypoperfusion of the brainstem (0.72 +/- 0.05 vs. 0.80 +/- 0.04, p < 0.0001) was marked and constant. We then tested whether perfusion to the brainstem in ME/CFS patients differs from that in normals, patients with major depression, and others with epilepsy. Data from a total of 146 subjects were included in the present study: 40 normal volunteers, 67 patients with ME/CFS (24 in the pilot study, 16 with no psychiatric disorders, 13 with ME/CFS and depression, 14 with ME/CFS and other psychiatric disorders), 10 epileptics, 20 young depressed patients and 9 elderly depressed individuals. Brain perfusion ratios were calculated using 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) and single-photon emission tomography (SPET) with a dedicated three-detector gamma camera computer/system (GE Neurocam). Brain-stem hypoperfusion was confirmed in all ME/CFS patients. Furthermore, the 16 ME/CFS patients with no psychiatric disorders and the initial 24 patients in the pilot study showed significantly lower brainstem perfusion (0.71 +/- 0.03) than did depressed patients (0.77 +/- 0.03; ANOVA, p < 0.0001). Patients with ME/CFS have a generalized reduction of brain perfusion, with a particular pattern of hypoperfusion of the brainstem.

Abstract: When a single coil is used to measure perfusion by arterial spin labeling, saturation of macromolecular protons occurs during the labeling period. Induced magnetization transfer contrast (MTC) effects decrease tissue water signal intensity, reducing the sensitivity of the technique. In addition, MTC effects must be properly accounted for in acquiring a control image. This forces the image to a single slice centered between the labeling plane and the control plane. In this work, a two-coil system is presented as a way to avoid saturation of macromolecular spins during arterial spin labeling. The system consists of one small surface coil for labeling the arterial water spins, and a head coil for MRI, actively decoupled from the labeling coil by using PIN diodes. It is shown that no signal loss occurs due to MTC effects when the two-coil system is used for MRI of rat brain perfusion, enabling three-dimensional perfusion imaging. Using the two-coil system, a multi-slice MRI sequence was used to study the regional effects of amphetamine on brain perfusion. Amphetamine causes significant increases in perfusion in many areas of the brain including the cortex, cingulate, and caudate putamen, in agreement with previous results using deoxyglucose uptake to monitor brain activation.

Abstract: Over the last few years, diffusion and perfusion magnetic resonance (MR) imaging methods have found increasing user for monitoring the effects of cerebral ischemia under clinical and experimental conditions Blood perfusion can be visualized by studying the patency of the cerebrovascular bed (MR angiography), by recording exchange of diffusible tracers between blood and brain ([2H]water or [19F]trifluoromethane clearance), or by measuring the volume and transit time of the circulating blood (bolus track or spin-tagging imaging) In addition, changes in blood oxygenation level can be visualized by taking advantage of the susceptibility changes of the magnetic field homogeneity (functional or blood-oxygenation-level-dependent imaging) Diffusion imaging is based on the modulation of signal intensity by brain water diffusion Recording a series of diffusion-weighted images allows calculation of the apparent diffusion coefficient (ADC) and the reconstruction of quantitative ADC images Brain ADC changes are a function of intra-extracellular water homeostasis and therefore are a sensitive marker of ionic equilibrium Since disturbances of ion and water homeostasis are among the first pathological alterations induced by brain ischemia, diffusion imaging is able to detect the incipient injury within minutes Conversely, the reversal of these alterations is able to detect the incipient injury within minutes Conversely, the reversal of these alterations is an early and reliable predictor of postischemic recovery Applications of perfusion and diffusion imaging are reviewed in relation to the pathophysiology, the pathobiochemistry, and the therapy of evolving brain infarct after focal ischemia and the manifestation and reversal of ischemic injury during and after global ischemia

Abstract: Neuroimaging was revolutionized by the development of computed tomography (CT) and standard T 1 - and T 2 -weighted magnetic resonance imaging (MRI). Magnetic resonance imaging and CT can adequately distinguish hemorrhage from infarction and depict ischemic stroke 12 to 24 hours after onset. However, during the critical initial hours after the onset of ischemic stroke, these imaging technologies do not adequately demonstrate the location and extent of infarction. Diffusion-weighted MRI and perfusion imaging, as well as advances in magnetic resonance spectroscopy, will enhance our ability to evaluate ischemic stroke shortly after onset. Some of the uses of MRI techniques are as follows: (1) Diffusion-weighted imaging can depict the location and extent of the ischemic lesion as soon as a stroke patient is available for examination. (2) Perfusion imaging evaluates blood flow within the brain's microvasculature and can reveal regions of perfusion deficits corresponding to major vascular territories. (3) Magnetic resonance spectroscopy evaluates metabolic abnormalties associated with focal brain ischemia by specific biochemical measurements. These MRI techniques will rapidly provide important information to clinicians about ischemia, guiding diagnosis and helping in the development of acute stroke interventions to improve outcome. ( JAMA . 1995;274:908-911)

Abstract: This study compared the efficacy of dobutamine stress testing using 2-dimensional echocardiography and perfusion tomography for the noninvasive identification of coronary artery disease (CAD) in patients with left bundle branch block (LBBB). Twenty-four patients with permanent, complete LBBB (11 with previous myocardial infarction) were studied prospectively with dobutamine echocardiography and perfusion tomography. The presence of > 50% luminal diameter coronary stenosis was compared with the presence of dobutamine-induced fixed or reversible perfusion defects, and with resting or dobutamine-induced abnormalities of wall thickening. For each test, the left anterior coronary artery territory was compared with the circumflex and/or right coronary artery. Significant CAD was found in the left anterior descending coronary artery in 12 patients; all (100%) were identified by perfusion imaging, and 10 (83%, p = NS) by 2-dimensional stress echocardiography. In the 12 patients without left anterior descending CAD, scintigraphy was also positive in all (specificity: 0%), and echocardiography in only 1 (specificity: 92%, p < 0.01). The diagnostic accuracy was 50% and 87% (p < 0.05), respectively. This low specificity of perfusion tomography was improved by requiring an associated apical defect to indicate left anterior descending CAD and was corrected by restricting the diagnosis of coronary disease to those patients with partially reversible defects. In the circumflex and/or right coronary artery territory, sensitivity and specificity were similar using both techniques. We conclude that dobutamine-stress echocardiography is a specific and accurate test for the noninvasive identification of CAD, even in the left anterior descending artery territory of patients with LBBB.

Abstract: With the recent advances in interventional cardiology there is increasing need for characterization of the functional effects of coronary artery stenosis. Stress echocardiography and SPECT perfusion imaging are standard techniques for the qualitative assessment of regional function and perfusion in patients with proven or suspected coronary artery disease. However, Positron emission tomography (PET) provides quantitative measurements of regional myocardial perfusion. In combination with pharmacological stress testing, relative and absolute coronary reserve measurements can be used to define functional significance of regional coronary artery disease. First clinical results indicate that there is an overall agreement between angiographic and functional disease severity. However, there is a relatively large scatter of coronary reserve flow in patients with 50-90% coronary artery stenosis, which emphasizes the complimentary role of perfusion imaging in the prediction of functional severity. In addition, first studies in asymptomatic patients with a high risk for coronary artery disease suggest that PET coronary reserve flow measurement may be more sensitive than angiographic criteria for detection of early alterations in coronary vascular reactivity. Absolute quantification of blood flow may be useful in disease processes which affect the entire left ventricle such as vasculopathy in cardiac transplants, as well as endothelial dysfunction in patients with hypertension and cardiomyopathy. Future studies have to demonstrate the prognostic value of the quantitative estimate of coronary reserve as regards clinical outcome in patients with various coronary abnormalities. Quantitative flow measurements will be useful for monitoring progression and regression of coronary artery disease as well as assessment of acute and chronic therapy.

Abstract: We tested the relationship of nitrate-induced changes in 99m Tc-sestamibi perfusion tomography and first-pass radionuclide angiocardiography (FPRNA) with postrevascularization functional recovery of asynergic territories. Methods : Twenty-eight patients, all with prior infarction and left ventricular dysfunction, underwent two 99m Tc-sestamibi rest studies : one under baseline conditions and the other with nitrate infusion. The baseline study was repeated after revascularization. Changes in global and regional perfusion and ventricular function were evaluated by perfusion tomography and FPRNA. Hibernating myocardium was identified by functional recovery in postrevascularization FPRNA. Results : Eleven patients and 31 segments in 19 coronary territories had functional recovery. Nitrate-induced FPRNA changes showed poor agreement with postrevascularization modifications : kappa = 0.24, ns, for the global and kappa = 0.32, p < 0.01 for regional function. The agreement between nitrate-induced and postrevascularization perfusion changes was good both considering the patients (k = 0.57, p < 0.01) and the abnormal coronary territories (k = 0.63, p < 0.0005). The agreement of nitrate-induced perfusion changes with postrevascularization functional outcome was excellent on a patient (k = 1, p < 0.0005), and coronary territory basis (k = 0.82, p < 0.0005). Conversely, the agreement between nitrate and postrevascularization FPRNA was poor : k = 0.18, ns. Conclusion : These data suggest that the nitrate-induced changes in 99m Tc-sestamibi perfusion imaging are useful to detect hibernating myocardium which recovers its function after revascularization.

Abstract: Absolute quantification of pancreatic perfusion in man has been extremely difficult to date. This paper describes a relatively simple application of dynamic computed tomography to provide perfusion imaging of the human pancreas. Values for perfusion in eight normal pancreases ranged between 1.25 and 1.66 ml min" 1 ml" 1 (mean: 1.52 ml min" 1 ml" 1 ). Increased perfusion values were present in a patient with an islet cell tumour (overall perfusion 2.11 ml min" 1 ml" 1 ) and a patient with Wilson's disease (3.43 ml min" 1 ml" 1 ). Pancreatic perfusion was reduced in a patient with diabetes (0.60 ml min" 1 ml" 1 ) and in a failing pancreatic transplant (0.97 ml min" 1 ml" 1 ). The combination of functional information and good spatial detail afforded by computed tomography (CT) perfusion imaging means the technique is well suited for the evaluation of the human pancreas. It is currently the only technique which allows non-invasive absolute quantification of pancreatic perfusion.

Abstract: Early reports of the prevalence, diagnosis, and outcomes of coronary artery disease (CAD) in women have led to the acceptance of several myths concerning noninvasive diagnostic studies in women. Many of the myths can be explained by age-related differences in prevalence, methodological errors that exclude women from enrollment, worse clinical baseline risk profiles, comorbid diseases at the time of interventions, and smaller coronary vessels. Awareness of these age-related prevalence factors in women and the potential for delaying the onset of CAD by estrogen treatment in postmenopausal women must be considered in assessing the accuracy of diagnostic studies. The critical role of noninvasive testing in women is to diagnose CAD accurately in a population with a lower prevalence of disease prior to the development of more severe clinical manifestations when therapeutic interventions have a higher risk and a poor outcome. Exercise radionuclide ventriculography has lower specificity in women, which may be due to gender differences in the response to excercise. Radionuclide perfusion imaging for the detection of CAD is accurate, there is extensive published literature, and it is used widely. High-dose dipyridamole in combination with echocardiography is not widespread in the United States; most pharmacologic echocardiographic studies are performed using dobutamine, and there are no reports on gender differences using dobutamine echocardiography. At this time, however, there is a paucity of published data on accuracy and no information on the prognostic value of this method. Both perfusion imaging and echocardiography have a better diagnostic accuracy than electrocardiographic stress testing. Myocardial perfusion imaging with thallium-201 or Tc-99m sestamibi identifies not just the presence or absence of CAD, it also prognostically identifies those patients with more severe disease who may benefit from invasive diagnostic testing and possible therapeutic interventions. Technetium-99m perfusion agents offer several advantages over thallium-201 : less attenuation, the ability to measure first-pass ejection fraction, and gated image acquisition. All 3 of these characteristics are expected to improve both sensitivity and specificity in women.

Abstract: UNLABELLED We compared TcN-NOET [bis(N-ethoxy, N-ethyl dithiocarbamato)nitrido 99mTc] and 201Tl images to estimate the utility of this compound in the detection of coronary artery disease (CAD). METHODS Twenty-five patients undergoing cardiac catheterization had stress-redistribution-reinjection 201Tl SPECT imaging, stress-delayed (2, 4 and 6 hr postinjection) and rest-delayed (4 hr postinjection) TcN-NOET SPECT imaging. RESULTS Nineteen patients had coronary stenosis > or = 50% and six were normal. Stress TcN-NOET and 201Tl imaging were concordant for the presence of CAD in 22/25 patients (88%, kappa = 0.76 +/- 0.20). The overall sensitivity of TcN-NOET SPECT imaging was 74% (14/19 patients) and 68% (13/19 patients) for 201Tl SPECT imaging. The specificity was 100% (6/6 patients) for both techniques. The overall agreement of TcN-NOET and 201Tl for the presence of disease in individual coronary arteries was 96% (72/75 arteries, kappa = 0.92 +/- 0.16). Segmental analysis of stress images showed a concordance in 211/225 segments (94%, kappa = 0.82 +/- 0.09). Comparison of the 4-hr images showed a concordance between 201Tl and TcN-NOET in 21/23 patients. Following TcN-NOET injection at rest, seven patients had a defect on the initial images, which had normalized 4 hr postinjection in four patients (57%). CONCLUSION Perfusion imaging with TcN-NOET and 201Tl gives comparable diagnostic information in patients undergoing exercise testing for assessment of CAD. Because of the normalization of myocardial activity 4 hr after injection in some patients, we conclude that TcN-NOET is a potential technetium compound equivalent to 201Tl.

Abstract: Background and Purpose The present study was performed to examine the potential of diffusion-weighted (DW) imaging and dynamic first-passage bolus tracking of susceptibility contrast agents (perfusion imaging) for early in vivo evaluation of the effects of treatment with the free radical scavenger U74389G in a rat model of temporary focal ischemia. Methods After 45 minutes of middle cerebral artery occlusion, the treatment group (n=9) received an infusion of U74389G, and the control group (n=9) received the identical volume of the vehicle. Reperfusion was instituted in both groups after 120 minutes of middle cerebral artery occlusion. The DW images were collected during middle cerebral artery occlusion and reperfusion and were compared with histologically assessed areas of tissue injury after 2 hours of reperfusion. The dynamic perfusion series were processed on a pixel-to-pixel basis to produce parametric maps reflecting the maximum reduction in the signal obtained during the first passage of the contrast agent and the time delay between the arrival of the bolus and the point of maximum contrast-agent effect. Results The area of ischemic injury, as assessed from the DW imaging at 60 minutes of reperfusion, was significantly smaller in the treatment group: 9±8% of ipsilateral hemisphere compared with 19±8% in the control group. The histological examination after 2 hours of reperfusion demonstrated an area of ischemic injury of 10±8% for the treatment group compared to 25±10% in the control group. In the treatment group, the perfusion imaging showed a reduction in time delay to maximum effect of the contrast agent in the ischemic hemisphere compared with the control group. Conclusions The DW imaging during early reperfusion showed a protective effect of postocclusion treatment with the free radical scavenger U74389G. The improvement of time delay to maximum effect of the contrast agent observed in the perfusion imaging of the treatment group may reflect an improvement in the collateral flow to the ischemic tissue.

Abstract: UNLABELLED Lung uptake of 201Tl is a reliable marker of left ventricular dysfunction. The goal of our study was to establish whether the evaluation of lung-to-heart uptake ratios (LHR) with 99mTc-sestamibi imaging may provide valuable information. METHODS We studied 72 male subjects with recent anterior myocardial infarction undergoing 99mTc-sestamibi first-pass ventriculography and SPECT perfusion imaging. A group of 46 gender-matched subjects with low pre-test likelihood of CAD and normal exercise and rest 99mTc-sestamibi perfusion images was used as a control. The lung-to-heart count ratios (LHR) were calculated on planar projections from the sets of SPECT images. RESULTS Both groups were studied at rest and after a symptom-limited exercise tolerance test. In the control group a significant decrease in LHR was observed during stress (p < 0.001). The infarcted group showed significantly higher LHR values both at rest and at stress. Exercise and rest LHR values did not differ significantly. A positive correlation was observed between LHR values and left ventricular ejection fraction at rest and stress. CONCLUSION LHR, measured by 99mTc-sestamibi imaging, gives clinically useful information. Both resting and postexercise values are correlated with ejection fraction and should predict left ventricular dysfunction.

Abstract: In the elderly, asymptomatic white matter hyperintensities are common on T2-weighted magnetic resonance imaging (MRI). In symptomatic patients, such MRI appearances correlate with varied postmortem findings including demyelination or stroke. What structural correlates underlie the T2 hyperintensities in patients whose lesions are asymptomatic is controversial. Therefore, in order to investigate the underlying metabolism and perfusion in white matter lesions (exhibiting T2 hyperintensity), 13 patients underwent proton magnetic resonance spectroscopy and dynamic gadolinium-DTPA perfusion-weighted MR imaging. N-acetyl aspartate (NA) levels were reduced in the lesions compared with age-matched controls (P = 0.031), implying neuronal/axonal loss. Creatine levels were also reduced (P = 0.001). Choline levels were unchanged in the lesions. Lactate was identified in the lesions of 5 of the 13 patients. Although not statistically significant, perfusion studies exhibited a trend toward lower cerebral blood volumes in patients with high grade extracranial carotid stenosis and lactate-containing lesions. These findings suggest that neuronal/axonal loss underlies the majority of T2-weighted asymptomatic lesions in the older population, and in many cases these changes may be due to chronic ischemia.

Abstract: To define the clinical and adenosine test variables that predicted perioperative cardiac events, 122 patients who received adenosine radionuclide perfusion imaging before peripheral vascular surgery were reviewed. Events included pulmonary edema, an ischemic end point of acute myocardial infarction (AMI) or cardiac death. Five patients underwent coronary revascularization before the surgical procedure. Of the 117 remaining patients, 19 had pulmonary edema, 10 had an AMI, and 2 died after peripheral vascular surgery. Most of the patients (78%) were in an intermediate-risk group as indicated by the presence of > or = 1 clinical risk factor as defined by the Eagle criteria. The only predictor of perioperative pulmonary edema was a history of congestive heart failure (33% vs 4%; p = 0.002). No clinical variables predicted AMI or death. The adenosine variables that were univariate predictors of AMI and death were the number of reversible perfusion defects (1.75 +/- 1.84 vs 0.75 +/- 0.90; p = 0.001) and the number of coronary artery distributions with a radionuclide perfusion defect (1.33 +/- 0.64 vs 0.85 +/- 0.67; p = 0.022). The number of reversible perfusion defects was the only multivariate predictor of ischemic events (p = 0.017). The presence of > 1 reversible defect was associated with an increased frequency of ischemic events (68% vs 28%; p = 0.045). The sensitivity and specificity of > 1 reversible defect was 58% and 73%, respectively, with a positive and negative predictive value of 19% and 94%.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract: The diagnosis of acute cerebral ischemia remains difficult. Computed tomography and magnetic resonance tomography are not specific at early time points. Diffusion imaging a new technique for magnetic resonance imaging was introduced in experimental studies and shown to have much earlier sensitivity for acute ischemic infarction. Diffusion imaging demonstrated early hyperintensities within minutes after ischemic onset and correlated well with post-mortem studies of the final infarct size. On the basis of molecular motion of water, hyperintensities during ischemia on diffusion imaging are most likely related to the development of ischemia induced cytotoxic edema and to slower diffusional motion. Experimental treatment and reperfusion studies with diffusion imaging demonstrated lesion reversal in vivo. Continuous monitoring after induction of ischemia enables an in vivo demonstration of the evolution of the ischemic lesion. Quantitative analysis of the apparent diffusion coefficient may enable the differentiation of infarcted tissue in the core of the lesion from reversibly damaged tissue. Preliminary clinical studies demonstrated a superior sensitivity of diffusion imaging compared with T2-weighted imaging. Clinicians may be able in the near future to image early stroke and to assess therapy when the stroke is still evolving.

Abstract: Although an indomethacin-induced decrease of brain perfusion in preterm infants has been well established, the acute effects of this vasoactive drug on cerebral hemodynamics and oxygenation are not well documented. Using near infrared spectroscopy we monitored in 6 very preterm infants changes in cerebral blood volume (delta CBV) and cytochrome oxidase concentration (delta Cytaa3), used as relative measures of changes in brain perfusion and as an indicator for cellular oxygenation of brain tissue, during and up to 1 h after indomethacin infusion. delta CBV showed a quick blood-pressure-related increase as compared to baseline (preindomethacin values) during indomethacin infusion (averaged maximal increase 13%), followed by a sharp decrease below baseline values (averaged maximal decrease 24%). There was a sustained recovery to baseline during the registration period. delta Cytaa3 showed a small, early increase in 4 of 6 babies, followed by a substantial decrease below baseline in 5 babies. delta Cytaa3 showed only a partial recovery in those 5 babies during the study period. We conclude that a therapeutic dose of indomethacin may cause substantial swings in brain perfusion and a marked and rather longstanding decrease in Cytaa3, suggesting a decrease in cellular oxygenation of brain tissue. Awareness of these effects may be important in sick preterm babies during periods of pulmonary and cardiac instability.

Abstract: In this review, the clinical utility of echoplanar techniques in MRI of the brain is discussed. Comparison of high-resolution EPI with SE/turbo-SE shows high image quality of EPI in the supratentorial brain. In the infratentorial region, however, susceptibility artifacts limit image quality. For the assessment of neuronal brain activation utilizing the intrinsic contrast of blood (BOLD), EPI has definite advantages over other techniques of functional MRI. Due to its superior temporal resolution and multislice capabilities, EPI allows for analysis of complex neuronal activation patterns. Diffusion imaging benefits from the lack of bulk motion artifacts and serves primarily to detect early stroke. Three methods of perfusion imaging (rel. blood volume, rel. blood flow) are discussed: the susceptibility artifact method (T2*), the relaxitivity method (T1), and the signal-labelling technique (STAR). Perfusion imaging may have a clinical impact in the assessment of brain tumors and cerebral ischemia.

Abstract: Brain perfusion SPECT was performed in an epileptic patient with a rare form of diffuse subcortical laminar heterotopia using 99m Tc-HMPAO. MRI demonstrated generalized laminar heterotopia underlying the cortical mantle. Interictal SPECT imaging revealed identical or increased perfusion of the laminar heterotopia as compared with that of the overlying cortical mantle. Moreover, SPECT revealed low perfusion in the left temporal lobe that agreed with the seizure type of complex partial seizures and the EEG finding of frequent generalized spike-wave complexes with a slight left-sided dominance. Brain SPECT imaging may be useful for appropriate diagnosis of gray matter heterotopia and for detection of functionally focal abnormality associated with epilepsy

Abstract: Single-photon emission computed tomography (SPECT) is a helpful tool for the management of stroke patients. Brain perfusion SPECT can help differentiate an ischemic event from peri-ictal phenomena such as Todd's paresis. Initial data suggest that SPECT may be useful in prognosticating the likelihood of an early stroke after a transient ischemic attack and in distinguishing lacunar from cortical stroke. After an acute stroke, early SPECT depicts the area of ischemia with greater accuracy than either computed tomography or magnetic resonance imaging. When the perfusion defect is large, the likelihood of hemorrhagic complications or herniation increases. Reperfusion of an arterial territory after thrombolysis can be documented more conveniently with SPECT than with angiography. SPECT before and after the injection of acetazolamide has been used to assess the vascular reserve in patients with severe stenosis of the proximal vessels of the cerebrovascular tree. Combined with transcranial Doppler studies, SPECT is used to document ischemia after subarachnoid hemorrhage. It has also been used to assess the effect of arterial ligation intended to treat arteriovenous malformations or aneurysms on brain perfusion and to evaluate ischemia secondary to pressure from an intracranial hemorrhage.