Areas Of High Perfusion Research Articles

Three-Dimensional Arterial Spin Labeling-Guided Sub-Volume Segmentation of Radiotherapy in Adult Non-Enhancing Low-Grade Gliomas.

ObjectiveThe present study aimed to evaluate the feasibility of sub-volume segmentation for radiotherapy planning of adult non-enhancing low-grade gliomas (NE-LGGs) guided by three-dimensional arterial spin labeling (3D-ASL). The differences in high- and low-perfusion areas of NE-LGGs were analyzed using multi-sequence magnetic resonance imaging (MRI) radiomics.MethodsFifteen adult patients with NE-LGGs were included in the study. MR images, including T1-weighted imaging (T1WI), T2 Propeller, T2 fluid-attenuated inversion recovery (T2 Flair), 3D-ASL, and contrast-enhanced T1WI (CE-T1WI), were obtained. The gross tumor volume (GTV) was delineated according to the hyperintensity on T2 Flair. The GTV was divided into high- and low-perfusion areas, namely GTV-ASL and GTV-SUB, respectively, based on the differences in cerebral blood flow (CBF) value. The volumes and CBF values of high- and low-perfusion areas were measured and compared. The least absolute shrinkage and selection operator (LASSO) regression was used to select the optimal features of all MR maps. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic accuracy of the absolute CBFmean (aCBFmean), relative CBFmean (rCBFmean, normalized by the CBF value of the normal gray matter), and screened features in differentiating high- and low-perfusion areas.ResultsAmong the enrolled patients, three (20%) patients with NE-LGGs showed focal intra- and post-radiotherapy contrast enhancement within a prior high-perfusion area of 3D-ASL. The volume ratio of the GTV-ASL to the GTV was (37.08% ± 17.88)% (46.26 ± 44.51 vs. 167.46 ± 209.64 cm3, P = 0.000). The CBFmean in the high-perfusion area was approximately two times of that in the edema area or normal gray matter (66.98 ± 18.03 vs. 35.19 ± 7.75 or 33.92 ± 8.48 ml/100g/min, P = 0.000). Thirteen features were screened, seven of which were extracted from 3D-ASL. The area undercurve (AUC) values of aCBFmean, rCBFmean, and firstorder_10Percentile from 3D-ASL were more than 0.9, of which firstorder_10Percentile was the highest. Their cut-off values were 44.16 ml/100 g/min, 1.49 and 31, respectively.ConclusionThe difference in blood perfusion in the GTV can be quantified and analyzed based on 3D-ASL images for NE-LGGs, which could guide the sub-volume segmentation of the GTV. 3D-ASL should become a routine method for NE-LGGs during simulation and radiotherapy.

Precision radiotherapy by SPECT lung functional imaging in NSCLC

Background: Single Photon Emission Computed Tomography (SPECT) could be used to avoid the non-affected perfusion areas in patients with non-small-cell lung cancer (NSCLC) and to potentially reduce lung toxicity. The aim of this study is to compare dosimetric differences between two different 3D-conformal treatment plans, with and without CT/SPECT contribution. Methods: Simulation Computed tomography (CT) scans were accurately co-registered with SPECT scans and three different areas, based on SPECT intensity perfusion, were contoured: low perfusion (LP), medium perfusion (MP) and high perfusion (HP). Two different 3D-conformal plans, with co-planar and nonco-planar fields, were generated; one without SPECT information (anatomic plan), and one using the perfusion area identified with functional imaging (functional plan). Results: 9 patients were planned and a total of 18 plans were available for analysis. Anatomical and functional plans resulted in comparable planning target volume (PTV) coverage. In the functional plans, a significant reduction of dose in high perfusion areas was reported. The reduction of HP-V20 Gy values ranged from 15% to 8% (p = 0.046), the ipsiHP-V20 Gy from 38% to 22% (p = 0.028) and ipsiHP-Dmean reduction from 16 Gy to 12 Gy (p = 0.039). No significant differences in other organs at risk (OARs) metrics were reported between anatomical and functional plans. Conclusions: Despite the few cases reported, the strength of our study lies in the reported benefit of functional lung information in 3D conformal radiation planning, without compromising target coverage or worsening dose distribution to the OARs. There is an urgent need for prospective clinical and randomized trials in order to define the role of lung functional imaging in reducing toxicity in clinical practice.

Evaluation of Fluorinated Cromolyn Derivatives as Potential Therapeutics for Alzheimer's Disease.

Cromolyn is an anti-neuroinflammatory modulator with a multifactorial mechanism of action that has been shown to inhibit amyloid-β (Aβ) aggregation and enhance microglial uptake and clearance of Aβ. We report the effects of fluoro-cromolyn derivatives on microglial cell toxicity and microglial clearance of Aβ42. Microglial cell toxicity for cromolyn derivatives were determined in naive BV2 microglial cells. Microglial clearance assays were performed with Aβ42 in naive BV2 microglial cell line and single cell clone BV2 line expressing CD33WT. PET imaging was performed for three F-18 analogs in a rhesus macaque. All compounds but derivative 8 exhibited low microglial cell toxicity. Cromolyn 1 and derivatives 2, 4, and 7 displayed an increased uptake on Aβ42 in naïve BV2 microglial cells. Derivative 4 increased Aβ42 uptake in a dose-dependent manner and at 75μM resulted in a one-fold increase in Aβ42 uptake in BV2-CD33WT. PET imaging for three [18F]cromolyn analogs revealed the order of brain tracer penetration to be 4a > 10 > 2a. Tracer 4a exhibited enhanced uptake in areas of high perfusion (putamen, grey matter, and cerebellum) and lower signal in areas of lower perfusion (caudate, thalamus, and white matter). Substantial uptake of Aβ42 in both naïve BV2 and BV2-CD33WT cells observed with 4 indicate conversion of microglial cells from a pro-inflammatory to an activation state favoring Aβ phagocytosis/clearance. These findings suggest that a fluoro-cromolyn analog could reduce fibril-prone Aβ42in vivo and thereby serve as a therapeutic for the treatment and prevention of AD.

Safety and efficacity of microwave ablation for colorectal metastases near a vascular vessel: short-terme result of a single institute

Background: Microwave ablation(mwa) is gaining wide acceptance. Many centers consider it as the first-line treatment for tumors less than 3 cm. RF energy is less efficient in treating tissues in high perfusion areas. A prospective study was started at our Institute to evaluate the safety and efficacy of mwa for colorectal liver metastasis(CLM)located near large vessels. Methods: Between March 2015 and Septemeber 2016, 44 patients underwent intraoperative mwa for liver tumors. Among them, 32 patients were treated for CLM. Twenty-one patients had CLM smaller than 3 cm and located near large vessels. Liver laboratory tests and postoperative morbidity were evaluated. The results of postoperative CT scans were checked for signs of local recurrence. Results: Surgery was performed by laparoscopy in 7 patients, by laparotomy in 13 patients and by thoracotomy in one case with CLM in segment VIII. Thirteen patients had associated mwa with minor liver resections, 4 patients had associated colorectal resections and only 4 patients had only mwa.Four patients were treated for local recurrence within a previous wedge resection or RFA. Overall morbidity rate was 19% with 4 minor complications. In the group of patients treated only with mwa, 1 case of liver hematoma occurred. The median follow-up was 6 months(4-17 months) and all patients are local recurrence-free. Conclusion: The present study suggests that the mwa near large vessels is a safe and effective method in short term basis. Still, long term outcomes have to be assessed.

Application of MRS- and ASL-guided navigation for biopsy of intracranial tumors.

The diagnosis of a tumor depends on accurate identification of the target area for biopsy. However, tumor heterogeneity and the inability of conventional structural data for identifying the most malignant areas can reduce this accuracy. To evaluate the feasibility and practicality of magnetic resonance spectroscopy (MRS)- and arterial spin labeling (ASL)-guided MRI navigation for needle biopsy of intracranial tumors. Thirty patients with intracranial tumors who underwent intraoperative stereotactic biopsy were retrospectively analyzed. Contrast-enhanced 3D-BRAVO or 3D-T2FLAIR structural data, combined with MRS and ASL data, were used to identify the target area for biopsy. High-choline or high-perfusion sites were chosen preferentially, and then the puncture trajectory was optimized to obtain specimens for histopathologic examination. Twenty-two specimens were collected from 20 glioma patients (two specimens each were collected from two patients) and ten specimens were collected from ten lymphoma patients. The diagnosis rate after the biopsy was 93.3% (28/30). Two gliomas were initially diagnosed as gliosis and subsequently diagnosed correctly after the collection of a second biopsy specimen. Combined MRS and ASL helped target selection in 23 cases (76.7%), including three cases each of low-enhancing and non-enhancing gliomas. In two cases, the target selection decision was changed because the areas initially chosen on the basis of positron emission tomography data did not match the high-perfusion areas identified with ASL. Compared with conventional MRI, combined MRS and ASL improved the accuracy of target selection for the stereotactic biopsy of intracranial tumors.

Quantitative dynamic susceptibility contrast perfusion-weighted imaging-guided customized gamma knife re-irradiation of recurrent high-grade gliomas

Treatment of recurrent high-grade gliomas (rHGG) has always been challenging. This study aimed to explore the treatment effect of quantitative dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI)-guided gamma knife radiosurgery (GKRS) on rHGG. Between April 2014 and July 2016, 26 consecutive patients were treated by quantitative DSC-PWI-guided GKRS as salvage treatment for rHGG. The gross tumor volume (GTV) was defined as the high perfusion area on absolute cerebral blood volume maps, with a cutoff value of 22ml/100g. The clinical target volume (CTV) encompassed the GTV by 3mm. Overall survival (OS) and progression-free survival (PFS) were calculated by the Kaplan-Meier method. Prognostic factors were tested by the log-rank (Mantel-Cox) test. With a median follow-up of 32 months, the median PFS after GKRS was 8months (95% CI [6, 12]); the 1- and 2-year survival rates were 30.8 and 11.5%, respectively. The median OS was 25.5months (95% CI [18, 40]); the 1- and 2-year survival rates were 96.2 and 57.7%, respectively. Pathology grade and CTV were identified as prognostic factors for PFS. However, none of the parameters tested were independent prognostic factors for OS among these selected patients. No severe radiotoxicity was observed among all patients. Quantitative DSC-PWI-guided GKRS is feasible for the treatment of rHGG and that these outcomes remain to be validated. Despite this, we think that carefully selected patients can benefit from this treatment method.

106: Novel MRI detection of impaired placental blood flow and fetal oxygen reserve in a non-human primate model of gestational protein restriction

We have recently developed novel placenta-specific MRI protocols to estimate placental oxygen reserve using blood oxygenation levels (T2* imaging). High oxyhemoglobin concentration has long T2* and correlates with areas of high perfusion as validated by dynamic contrast enhanced (DCE) MRI. Short T2* relates to areas of high deoxyhemoglobin concentration. Here our objective was to evaluate the adverse effects of maternal malnutrition on placental oxygen reserve and placental perfusion in vivo in a non-human primate model of gestational protein restriction (PR). Rhesus macaques were fed a control diet (CON, 26% protein, n=8) or switched to either a 33% PR (17% protein, n=8) or 50% PR (13% protein, n=8) diet before and during pregnancy. All underwent Doppler ultrasound (D-US) and fetal biometry measurements followed by MRI consisting of T2* and DCE measurements at gestational day 85 (G85) and G135 (term is G168). D-US was used to measure uterine artery (Uta) and umbilical vein velocimetry and diameter to calculate Uta volume blood flow (cQuta) and placental volume blood flow (cQuv). Pregnancy loss rates were 0/8 in controls, 1/8 in 33% PR, and 3/8 in 50% PR (1 prior to G135). Animals fed a 50%PR diet had significantly smaller fetal abdominal circumference (G135) and lower cQuta (G135) and cQuv (G85 and G135) versus CON (Fig 1). Additionally, by DCE-MRI, placental blood flow was significantly lower at G135 in animals fed a 50% PR diet (Fig 1). Distributions of T2* throughout the placenta (Fig 2) show significant global reductions in T2* (blood oxyhemoglobin) in animals fed a 50% PR diet vs. CON (G85 and G135). These data from a relevant translational model demonstrate that a 50% gestational PR diet reduces maternal placental perfusion, decreases fetal oxygen availability and increases fetal mortality. However, animals fed a 33% PR diet were similar to CON suggesting that placental reserve capacity is able to compensate for some PR, but not a 50% reduction. The perturbations observed with placental blood flow and fetal oxygen availability may explain the noted increased risk of human growth restriction and stillbirth with severe PR diets in the developing world. Our imaging abilities have allowed early identification of pregnancies affected by placental dysfunction and is a first step in improving outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Optimization of arterial spin labeling MRI for quantitative tumor perfusion in a mouse xenograft model.

Perfusion is an important biomarker of tissue function and has been associated with tumor pathophysiology such as angiogenesis and hypoxia. Arterial spin labeling (ASL) MRI allows noninvasive and quantitative imaging of perfusion; however, the application in mouse xenograft tumor models has been challenging due to the low sensitivity and high perfusion heterogeneity. In this study, flow-sensitive alternating inversion recovery (FAIR) ASL was optimized for a mouse xenograft tumor. To assess the sensitivity and reliability for measuring low perfusion, the lumbar muscle was used as a reference region. By optimizing the number of averages and inversion times, muscle perfusion as low as 32.4 ± 4.8 (mean ± standard deviation) ml/100 g/min could be measured in 20 min at 7 T with a quantification error of 14.4 ± 9.1%. Applying the optimized protocol, heterogeneous perfusion ranging from 49.5 to 211.2 ml/100 g/min in a renal carcinoma was observed. To understand the relationship with tumor pathology, global and regional tumor perfusion was compared with histological staining of blood vessels (CD34), hypoxia (CAIX) and apoptosis (TUNEL). No correlation was observed when the global tumor perfusion was compared with these pathological parameters. Regional analysis shows that areas of high perfusion had low microvessel density, which was due to larger vessel area compared with areas of low perfusion. Nonetheless, these were not correlated with hypoxia or apoptosis. The results suggest that tumor perfusion may reflect certain aspect of angiogenesis, but its relationship with other pathologies needs further investigation.

Detection of clinically manifest and silent synovitis in the hands and wrists by fluorescence optical imaging

ObjectivesThe correct identification of synovitis is critical for achieving optimal therapy results. Fluorescence optical imaging (FOI) is a novel modality based on the use of an intravenous fluorophore, which enables...

AB1024 Clinically “Silent” Synovitis: Detected by Fluorescence Optical Imaging of the Hands & Wrists

BackgroundThe detection of sub-clinical synovial inflammation (“silent synovitis”) would be of critical importance for the detection of rheumatoid arthritis (RA) & other inflammatory arthritides, in its earliest pathophysiological stage (”pre-RA”)....

Facing contrast-enhancing gliomas: perfusion MRI in grade III and grade IV gliomas according to tumor area.

Tumoral neoangiogenesis characterizes high grade gliomas. Relative Cerebral Blood Volume (rCBV), calculated with Dynamic Susceptibility Contrast (DSC) Perfusion-Weighted Imaging (PWI), allows for the estimation of vascular density over the tumor bed. The aim of the study was to characterize putative tumoral neoangiogenesis via the study of maximal rCBV with a Region of Interest (ROI) approach in three tumor areas—the contrast-enhancing area, the nonenhancing tumor, and the high perfusion area on CBV map—in patients affected by contrast-enhancing glioma (grades III and IV). Twenty-one patients were included: 15 were affected by grade IV and 6 by grade III glioma. Maximal rCBV values for each patient were averaged according to glioma grade. Although rCBV from contrast-enhancement and from nonenhancing tumor areas was higher in grade IV glioma than in grade III (5.58 and 2.68; 3.01 and 2.2, resp.), the differences were not significant. Instead, rCBV recorded in the high perfusion area on CBV map, independently of tumor compartment, was significantly higher in grade IV glioma than in grade III (7.51 versus 3.78, P = 0.036). In conclusion, neoangiogenesis encompasses different tumor compartments and CBV maps appear capable of best characterizing the degree of neovascularization. Facing contrast-enhancing brain tumors, areas of high perfusion on CBV maps should be considered as the reference areas to be targeted for glioma grading.

OP06.07: Preliminary experience with microwave ablation for selective feticide in monochorionic twin pregnancies

Microwave ablation (MWA) is an alternative technique to radiofrequency ablation (RFA) and interstitial laser photocoagulation (ILP) in the treatment of some solid tumours. MWA offers the same benefits as RFA and ILP, but is less dependent on tissue properties (areas of high perfusion, tissues with poor electrical and thermal conductivity) and has the ability to heat faster in a larger volume. As opposed to RFA and ILP, we are not aware of previous experiences with MWA in fetal procedures, and we report here our preliminary experience. Review of two cases of monochorionic twins discordant for fetal abnormalities undergoing selective feticide by MWA below 18 weeks of gestation between November 2011 and March 2012. MW was performed using a 2.45-MHz generator (AMICA-GEN, HS Hospital Service, Aprilia, Italy) delivering energy through a 16-gauge internally cooled coaxial antenna. All the procedures were performed percutaneously under ultrasonographic guidance. The antenna was centred in the abdomen of the abnormal fetus close to the insertion of the umbilical cord. A single microwave energy application was delivered at 50 W net power at the applicator end, for 3 min. In case 1, one of the twins had a complex cardiac abnormality with hydrops; cervical length was 22 mm; MWA was performed at 17 + 3 weeks. There was PROM of the terminated twin 4 days later, and the entire pregnancy was lost after 7 days. In case 2, one of the twins had anencephaly; cervical length was 40 mm; MWA was performed at 16 + 2 weeks. The pregnancy carried on uneventfully, and a healthy infant was delivered at term. In both cases MWA was technically easy, and ultrasound evidence of tissue coagulation was seen immediately after the beginning of energy delivery. Our preliminary experience shows that MWA is easily applicable to intrafetal procedures. MWA has potential advantages over RFA and ILP: there is immediate evidence of tissue coagulation on ultrasound, the technique is less dependent on tissue properties. Evaluation in larger series is required.

Microvascular leakage and contrast enhancement as prognostic factors for recurrence in unfavorable low-grade gliomas

Perfusion estimates and microvascular leakage (MVL) were recently correlated with glioma angiogenesis and aggressiveness, but their role in predicting outcome of patients (pts) with unfavorable low-grade gliomas (ULGG) is unclear. Their prognostic value was then investigated, versus conventional factors such as age, neurological status, tumor size, and contrast enhancement (CE). Clinical and anatomical magnetic resonance imaging (MRI) criteria of a cohort of ULGG pts were prospectively evaluated. A dynamic T2*-weighted MR sequence was included to detect high-perfusion areas, using the maximal value of the relative cerebral blood volume (rCBV) estimate, and MVL. Conventional and microvascular characteristics were correlated with progression-free survival (PFS). Among the 46 pts included, the following features were present in 61%, 26%, 67%, and 26%, respectively: age >or=40 years, neurological deficits, tumor size >or=6 cm, and CE. High perfusion value was noted in 30% of cases and MVL in 52%. With median follow-up of 22 months (range 4-46 months), median PFS was 32 months [95% confidence interval (CI) 17-45 months]. On univariate analysis, CE, rCBV, and MVL were significantly correlated with PFS. On multivariate analysis, only CE and MVL were unfavorable factors, with hazard ratio of 3.0 and 7.3 and P value of 0.04 and 0.02, respectively. Different prognostic subgroups were identified, with 2-year PFS of 86%, 57%, and 19% for pts with no MVL, MVL without CE, and MVL with CE, respectively. MVL and CE seem to predict short-term outcome in ULGG pts.

Hyperoxia decreases cutaneous blood flow in high-perfusion areas

The mechanism by which hyperoxia decreases blood flow is still not understood. Hyperoxemia-induced vasoconstriction is known to occur in many organs, including brain and retina, skeletal muscle, and myocardium. Whether this also occurs in skin is unknown. This study was conducted in healthy volunteers exposed intermittently to 100% oxygen (F IO 2 1.0). Perfusion of forearm skin was measured by laser Doppler imaging (LDI). In series 1, it was measured in 7 subjects before, during, and after 15 min of oxygen breathing. In series 2, flow was measured, also during air and O 2 breathing, after perfusion was raised by (a) sympathetic blockade (induced by a topically applied local anesthetic) ( n = 9) and by (b) current-induced vasodilation ( n = 8). In normal unperturbed skin, there was no significant change with hyperoxia. When basal perfusion was raised by topical anesthesia or by current, there was also no change in mean perfusion overall with hyperoxia. However, areas with the highest perfusion (upper decile) showed a significant perfusion decrement with hyperoxia (− 30% and − 20%, respectively; p < 0.001). Vasoconstriction with hyperoxia has been demonstrated in human skin. The fact that it is observed only when flow is increased above basal levels and then only in high-flow vessels suggests that cutaneous blood flow control is primarily regulated by variables other than oxygen.

On the incorporation of multi-modality image registration into the radiotherapy treatment planning process.

A technique is presented that allows the direct use of physiological image sets in the radiation therapy treatment planning process. When fused to the treatment planning CT, physiological image studies may allow one to define physiological tumor subvolumes consisting of areas of possible chronic hypoxia, areas of high perfusion, areas of high diffusion, and areas containing high choline concentrations. These physiological tumor subvolumes could be selectively boosted to increase local control of malignant brain tumors once one has determined which of these physiological tumor subvolumes predicts for local tumor recurrence after conventional radiotherapy. In this technique a user assisted automatic registration technique is used that is based on an analytical estimate for the transformation matrix needed to register two rigid bodies. The only user input needed is three non-collinear points selected based on landmarks in the primary image and the corresponding three points in the secondary image. Since this registration technique uses two sets of at least three user-defined landmark points each of which has some selection error associated with it, the final registration will have an error that depends only on the selection error associated with the point sets. Since physiological image studies are acquired at the same setting as the T1- w MRI their spatial orientation with respect to the T1- w MRI is known. Therefore, the registration of multiple physiological image studies to the treatment planning CT can be accomplished by first correlating them to the T1- w MRI, and in a second step the T1- w MRI is then registered to the treatment planning CT. The desired registration of the physiological image studies to the treatment planning CT is then accomplished by simply composing the appropriate transformation matrices.

Spectral signature and heterodyne efficiency for different wavelengths in laser Doppler flowmetry.

Laser Doppler perfusion monitoring and imaging technologies generate time traces and two-dimensional flow maps of the microcirculation. With the goal of reaching different tissue depths, these technologies are equipped with lasers operating at different wavelengths lambda. The fact that the average scattering angle, at a single scattering event, between a photon and a red blood cell increases with lambda is compensated for by a 1/lambda effect in the scattering vector, rendering the average frequency shift virtually independent of the choice of wavelength. Monte Carlo simulations showed that the corresponding spectral signature of the Doppler signals for lambda = 632.8 nm and 780 nm were close to identical. The theoretical predictions were verified by calculating the centre-of-gravity (COG) frequency of the laser Doppler power spectral density for the two wavelengths from forearm and finger skin, representing a low and high perfusion area, respectively (forearm COG= 123 against 121 Hz, finger COG = 220 against 212 Hz). When the wavelength changes from 632.8 nm to 780 nm, the heterodyne efficiency of the detector and, thereby, the inherent system amplification increase. For tissues with identical microvascular flow conditions, the output signal therefore tends to increase in magnitude when shifting to longer wavelengths.

Acquired epileptiform opercular syndrome: a case report and results of single photon emission computed tomography and computer-assisted electroencephalographic analysis

We report here a girl aged 5 years 3 months with cryptogenic localization-related epilepsy who showed a prolonged episode characterized by dysarthria, dysphagia, drooling and paresis of the right arm associated with almost continuous diffuse sharp–slow wave complexes during sleep. These symptoms were not directly related to seizures or to each sharp–slow wave complex revealed by examination during the video electroencephalographic (EEG) recording. The interictal single photon emission compute tomography showed a localized high perfusion area in the left posterior frontal region. The introduction of clonazepam completely controlled the clinical symptoms as well as the EEG abnormality within 2 weeks. After 4 months of remission, a similar episode recurred which was associated with aggravation of EEG. The clinical and EEG characteristics of this patient were identical to those of acquired epileptiform opercular syndrome (AEOS), a newly proposed epileptic syndrome, in which a transient operculum syndrome develops in association with continuous spike-and-wave activity during slow sleep (CSWS). Computer-assisted EEG analysis demonstrated that the epileptic EEG focus was located in the left sylvian fissure, and produced secondary bilateral synchronous sharp–slow complexes. The present study further supports the hypothesis that the electrical interference by CSWS creates bilateral opercular dysfunction through the mechanism of secondary bilateral synchrony, thus producing AEOS.

Ventilation-perfusion matching in long-term microgravity.

We studied the ventilation-perfusion matching pattern in normal gravity (1 G) and short- and long-duration microgravity (microG) using the cardiogenic oscillations in the sulfur hexaflouride (SF(6)) and CO(2) concentration signals during the phase III portion of vital capacity single-breath washout experiments. The signal power of the cardiogenic concentration variations was assessed by spectral analysis, and the phase angle between the oscillations of the two simultaneously expired gases was obtained through cross-correlation. For CO(2), a significant reduction of cardiogenic power was observed in microG, with respect to 1 G, but the reduction was smaller and more variable in the case of SF(6). A shift from an in-phase condition in 1 G to an out-of-phase condition was found for both short- and long-duration microG. We conclude that, although the distribution of ventilation and perfusion becomes more homogeneous in microG, significant inhomogeneities persist and that areas of high perfusion become associated with areas of relatively lower ventilation. In addition, these modifications seem to remain constant during long-term exposure to microG.

Unilateral Diffuse Cortical Dysplasia: A Case Report

Purpose: A case of unilateral diffuse cortical dysplasia is presented, and the surgical strategy is discussed. Case Report: A 6‐year‐old girl with moderate mental retardation had had intractable epilepsy for 4 years with daily complex partial or generalized seizures. Magnetic resonance imaging demonstrated a schizen‐cephaly in the right occipital lobe. The wall of the cleft showed isointensity as white matter, and a mass of gray‐matter intensity was identified under the wall. The gray‐matter intensity lesion continued into the thalamus and midbrain. There was no hippocampal formation. Diffuse polymicrogyria was seen in the ipsiiateral fronto‐parietotemporal lobes. an electroencephalogram (EEG) showed interictal spikes predominantly in the right frontal and central areas, and a phase reversal was found in the right central lead. The ictal EEG was successfully recorded 4 times with prolonged video‐EEG monitoring. However, the laterality and localization of the seizure onset were unclear. Invasive recording was impossible because of the mental retardation. On interictal single‐photon‐emission computed tomography (SPECT) with 99mTc‐ECD, the right occipital lesion showed normal perfusion as gray matter, and a mild low‐perfusion area was observed in the right frontal and parietal lobes. the ictal SPECT revealed a remarkable high‐perfusion area in the lesion, including the neighboring cortex. A large craniotomy was performed, and the right occipital, parietal, and temporal lobes were exposed. The schizencephalic cyst was covered with a thick arachnoid membrane and continued into the lateral ventricle. The dysplastic lesion appeared as a glassy yellowish white mass. Around the lesion, the cortex showed diffuse polymicrogyria. An electrocorticogram (ECoG) was recorded from the surface of the lesion and polymicrogyria. Interictal spikes were recorded frequently in the polymicrogyria, but sporadically in the lesion. The epileptogenic zone, including the dysplastic lesion, was resected. The medial resectable margin of the lesion was determined intraoperatively by using a neuronavigation system (Viewing Wand, ISG Technologies, Toronto, Canada). After the en bloc resection, the ECoG was recorded again at the resected margin. Although rare epileptic activity persisted in the anterior margin, additional resection was not carried out to avoid additional neurologic impairment. The patient tolerated the surgery well and showed no additional neurologic deficits postoperatively. For 2 weeks after the surgery, the patient still had a few seizures every day. However, the number of seizures gradually decreased by 4 weeks after the surgery and disappeared after the seventh week. Complete seizure control was obtained for 9 months postoperatively with the same an‐ticonvulsive therapy as that used before the surgery. Histologic examination revealed that the surface of the lesion was covered with a layer of subpial gliosis. Under the gliosis, the lesion consisted of complicated glial bundles and cortical islands. Some neurons were observed even in the glial bundle. The gray matter had no laminar structure and contained cytomegalic and polynuclear neurons. In the neighboring cortex that showed polymicrogyria, normal cortical columnar structure was preserved. However, the neuronal density was higher than that in the normal cortex. Conclusions; Surgical indication for patients with diffuse cortical dysplasia is often neglected because of multiple seizure foci and mental disorders. However, it should be stressed that an excellent outcome is possible in some cases if the epileptic focus can be precisely defined. A neuronavigation system and intraoperative recording of the EcoG are useful for focus resection during surgery for epilepsy.

Local Cerebral Blood Flow Mapping by SPECT of N-isopropyl-p-[&lt;SUP&gt;123&lt;/SUP&gt;I] Iodoamphetamine in Comparison with &lt;SUP&gt;81m&lt;/SUP&gt;Kr Image

Local cerebral blood flow in 28 patients (aged from 13 to 71) with cerebrovascular disorders was studied 37 times by single photon emission computed tomography (SPECT) using N-isopropyl-p-[123I] iodoamphetamine (IMP), and compared with findings of X-ray computed tomography (CT) and 81mKr (Kr) perfusion images. There were three patients with occlusion of the internal carotid artery, two with stenosis of the internal carotid artery, six with occlusion of the middle cerebral artery, five with occlusion of the bilateral vertebral arteries, five with moyamoya disease, two with aortitis syndrome, and five with cerebral arteriovenous malformation. Examinations were performed using a rotating gamma camera with dual heads in both SPECT-IMP and SPECT-Kr. In the IMP study, both SPECT and planar images were obtained 30 and 120 minutes after intravenous injection of IMP. SPECT-Kr was performed by continuous infusion into the ascending aorta of 81mKr generated by an 81Rb-81mKr generator. Sampling time was about 20 minutes in 22 examinations and about 10 minutes in 15 examinations by SPECT-IMP, and about 4 minutes in all the examinations by SPECT-Kr. SPECT-IMP images 30 minutes after injection showed low perfusion area in all but four examinations in three patients: one patient with transient ischemic attack alone and two patients with aortitis syndrome. In 26 of the 33 examinations, SPECT-IMP images 30 minutes after injection revealed more extensive or obvious low perfusion areas than the low density lesions in X-ray CT, and low perfusion even in the areas without low density lesions. In all of the 33 examinations, low perfusion areas shown in SPECT-IMP images 30 minutes after injection became obscure after 120 minutes. In respect to representation of local cerebral blood flow, SPECT-IMP images 30 minutes after injection seemed to be better than after 120 minutes. In 26 of the 33 examinations, low perfusion areas in SPECT-Kr images were more extensive and obvious than in SPECT-IMP images. However, SPECT-IMP images seemed to show a more definite anatomy than SPECT-Kr images. The nidus of a cerebral arteriovenous malformation was shown to be a low perfusion area in SPECT-IMP images, but appeared as a high perfusion area in SPECT-Kr images. It is likely that SPECT-Kr images showed mainly intravascular flow of the nidus. In comparison with SPECT-Kr, SPELT-IMP was considered to be an easy and noninvasive three dimensional study of local cerebral blood flow.