Full automation of total metabolic tumor volume from FDG-PET/CT in DLBCL for baseline risk assessments.

BACKGROUND: Current radiological assessments of 18fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging data in diffuse large B-cell lymphoma (DLBCL) can be time consuming, do not yield real-time information regarding disease burden and organ involvement, and hinder the use of FDG-PET to potentially limit the reliance on invasive procedures (e.g. bone marrow biopsy) for risk assessment. METHODS: Our aim is to enable real-time assessment of imaging-based risk factors at a large scale and we propose a fully automatic artificial intelligence (AI)-based tool to rapidly extract FDG-PET imaging metrics in DLBCL. On availability of a scan, in combination with clinical data, our approach generates clinically informative risk scores with minimal resource requirements. Overall, 1268 patients with previously untreated DLBCL from the phase III GOYA trial (NCT01287741) were included in the analysis (training: n = 846; hold-out: n = 422). RESULTS: Our AI-based model comprising imaging and clinical variables yielded a tangible prognostic improvement compared to clinical models without imaging metrics. We observed a risk increase for progression-free survival (PFS) with hazard ratios [HR] of 1.87 (95% CI: 1.31-2.67) vs 1.38 (95% CI: 0.98-1.96) (C-index: 0.59 vs 0.55), and a risk increase for overall survival (OS) (HR: 2.16 (95% CI: 1.37-3.40) vs 1.40 (95% CI: 0.90-2.17); C-index: 0.59 vs 0.55). The combined model defined a high-risk population with 35% and 42% increased odds of a 4-year PFS and OS event, respectively, versus the International Prognostic Index components alone. The method also identified a subpopulation with a 2-year Central Nervous System (CNS)-relapse probability of 17.1%. CONCLUSION: Our tool enables an enhanced risk stratification compared with IPI, and the results indicate that imaging can be used to improve the prediction of central nervous system relapse in DLBCL. These findings support integration of clinically informative AI-generated imaging metrics into clinical workflows to improve identification of high-risk DLBCL patients. TRIAL REGISTRATION: Registered clinicaltrials.gov number: NCT01287741.

RIPK3 deficiency or catalytically inactive RIPK1 provides greater benefit than MLKL deficiency in mouse models of inflammation and tissue injury.

Necroptosis is a caspase-independent form of cell death that is triggered by activation of the receptor interacting serine/threonine kinase 3 (RIPK3) and phosphorylation of its pseudokinase substrate mixed lineage kinase-like (MLKL), which then translocates to membranes and promotes cell lysis. Activation of RIPK3 is regulated by the kinase RIPK1. Here we analyze the contribution of RIPK1, RIPK3, or MLKL to several mouse disease models. Loss of RIPK3 had no effect on lipopolysaccharide-induced sepsis, dextran sodium sulfate-induced colitis, cerulein-induced pancreatitis, hypoxia-induced cerebral edema, or the major cerebral artery occlusion stroke model. However, kidney ischemia-reperfusion injury, myocardial infarction, and systemic inflammation associated with A20 deficiency or high-dose tumor necrosis factor (TNF) were ameliorated by RIPK3 deficiency. Catalytically inactive RIPK1 was also beneficial in the kidney ischemia-reperfusion injury model, the high-dose TNF model, and in A20(-/-) mice. Interestingly, MLKL deficiency offered less protection in the kidney ischemia-reperfusion injury model and no benefit in A20(-/-) mice, consistent with necroptosis-independent functions for RIPK1 and RIPK3. Combined loss of RIPK3 (or MLKL) and caspase-8 largely prevented the cytokine storm, hypothermia, and morbidity induced by TNF, suggesting that the triggering event in this model is a combination of apoptosis and necroptosis. Tissue-specific RIPK3 deletion identified intestinal epithelial cells as the major target organ. Together these data emphasize that MLKL deficiency rather than RIPK1 inactivation or RIPK3 deficiency must be examined to implicate a role for necroptosis in disease.

Mouse Models of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disorder characterized by synovitis that leads to cartilage and bone erosion by invading fibrovascular tissue. Mouse models of RA recapitulate many features of the human disease. Despite the availability of medicines that are highly effective in many patient populations, autoimmune diseases (including RA) remain an area of active biomedical research, and consequently mouse models of RA are still extensively used for mechanistic studies and validation of therapeutic targets. This review aims to integrate morphologic features with model biology and cover the key characteristics of the most commonly used induced and spontaneous mouse models of RA. Induced models emphasized in this review include collagen-induced arthritis and antibody-induced arthritis. Collagen-induced arthritis is an example of an active immunization strategy, whereas antibody- induced arthritis models, such as collagen antibody-induced arthritis and K/BxN antibody transfer arthritis, represent examples of passive immunization strategies. The coverage of spontaneous models in this review is focused on the TNFΔ (ARE) mouse, in which arthritis results from overexpression of TNF-α, a master proinflammatory cytokine that drives disease in many patients.

Fully-automated, high-throughput micro-computed tomography analysis of body composition enables therapeutic efficacy monitoring in preclinical models.

BACKGROUND: The ability to non-invasively measure body composition in mouse models of obesity and obesity-related disorders is essential for elucidating mechanisms of metabolic regulation and monitoring the effects of novel treatments. These studies aimed to develop a fully automated, high-throughput micro-computed tomography (micro-CT)-based image analysis technique for longitudinal quantitation of adipose, non-adipose and lean tissue as well as bone and demonstrate utility for assessing the effects of two distinct treatments. METHODS: An initial validation study was performed in diet-induced obesity (DIO) and control mice on a vivaCT 75 micro-CT system. Subsequently, four groups of DIO mice were imaged pre- and post-treatment with an experimental agonistic antibody specific for anti-fibroblast growth factor receptor 1 (anti-FGFR1, R1MAb1), control immunoglobulin G antibody, a known anorectic antiobesity drug (rimonabant, SR141716), or solvent control. The body composition analysis technique was then ported to a faster micro-CT system (CT120) to markedly increase throughput as well as to evaluate the use of micro-CT image intensity for hepatic lipid content in DIO and control mice. Ex vivo chemical analysis and colorimetric analysis of the liver triglycerides were performed as the standard metrics for correlation with body composition and hepatic lipid status, respectively. RESULTS: Micro-CT-based body composition measures correlate with ex vivo chemical analysis metrics and enable distinction between DIO and control mice. R1MAb1 and rimonabant have differing effects on body composition as assessed by micro-CT. High-throughput body composition imaging is possible using a modified CT120 system. Micro-CT also provides a non-invasive assessment of hepatic lipid content. CONCLUSIONS: This work describes, validates and demonstrates utility of a fully automated image analysis technique to quantify in vivo micro-CT-derived measures of adipose, non-adipose and lean tissue, as well as bone. These body composition metrics highly correlate with standard ex vivo chemical analysis and enable longitudinal evaluation of body composition and therapeutic efficacy monitoring.

Targeting FGF19 inhibits tumor growth in colon cancer xenograft and FGF19 transgenic hepatocellular carcinoma models.

Although fibroblast growth factor 19 (FGF19) can promote liver carcinogenesis in mice its involvement in human cancer is not well characterized. Here we report that FGF19 and its cognate receptor FGF receptor 4 (FGFR4) are coexpressed in primary human liver, lung and colon tumors and in a subset of human colon cancer cell lines. To test the importance of FGF19 for tumor growth, we developed an anti-FGF19 monoclonal antibody that selectively blocks the interaction of FGF19 with FGFR4. This antibody abolished FGF19-mediated activity in vitro and inhibited growth of colon tumor xenografts in vivo and effectively prevented hepatocellular carcinomas in FGF19 transgenic mice. The efficacy of the antibody in these models was linked to inhibition of FGF19-dependent activation of FGFR4, FRS2, ERK and beta-catenin. These findings suggest that the inactivation of FGF19 could be beneficial for the treatment of colon cancer, liver cancer and other malignancies involving interaction of FGF19 and FGFR4.

Cerebral hemodynamics in a healthy population measured by dynamic susceptibility contrast MR imaging.

PURPOSE: To establish reference data and to study age-dependency for cerebral perfusion in various regions of the brain in a healthy population. MATERIAL AND METHODS: Eighty healthy subjects of both genders from 22 to 85 years of age were studied with spin echo echo-planar dynamic susceptibility contrast MR imaging (DSC MRI) at 1.5 T. Cerebral blood volume (CBV), cerebral blood flow (CBF), and contrast agent mean transit time (MTT) were calculated bilaterally for 20 distinct neuroanatomic structures. RESULTS: In gray matter, the following values were found (mean +/- SD): CBV (4.6 +/- 1.0 ml/100 g), CBF (94.2 +/- 23.0 ml/100 g/min), and MTT (3.0 +/- 0.6 s), and in white matter: CBV (1.3 +/- 0.4 ml/100 g), CBF (19.6 +/- 5.8 ml/100 g/min), and MTT (4.3 +/- 0.7 s). The perfusion parameters did not change with age, except for a tendency to an increase in gray matter MTT and CBV. Males exhibited higher MTT and CBV than females. No hemispheric difference was found in either gender. CONCLUSION: Cerebral hemodynamics can be assessed with DSC MRI. Age itself seems to have only a marginal effect on cerebral perfusion in healthy population.

Multispectral analysis of the temporal evolution of cerebral ischemia in the rat brain.

A major difficulty in staging and predicting ischemic brain injury by magnetic resonance (MR) imaging is the time-varying nature of the MR parameters within the ischemic lesion. A new multispectral (MS) approach is described to characterize cerebral ischemia in a time-independent fashion. MS analysis of five MR parameters (mean diffusivity, diffusion anisotropy, T2, proton density, and perfusion) was employed to characterize the progression of ischemic lesion in the rat brain following 60 minutes of transient focal ischemia. k-Means (KM) and fuzzy c-means (FCM) classification methods were employed to define the acute and subacute ischemic lesion. KM produced an estimate of lesion volume that was highly correlated with postmortem infarct volume, independent of the age of the lesion. Overall classification rates for KM exceeded FCM at acute and subacute time points as follows: KM, 90.5%, 94.4%, and 95. 9%; FCM, 82.4%, 90.6%, and 82.6% (for 45 minutes, 180 minutes, and 24-120 hours post MCAO groups). MS analysis also offers a formal method of combining diffusion and perfusion parameters to provide an estimate of the ischemic penumbra (KM classification rate = 70.3%). J. Magn. Reson. Imaging 2000;12:842-858.

Broad-spectrum cation channel inhibition by LOE 908 MS reduces infarct volume in vivo and postmortem in focal cerebral ischemia in the rat.

Cation channels conduct calcium, sodium and potassium, cations that are likely deleterious in the evolution of focal ischemic injury. We studied the effects of a novel, broad-spectrum inhibitor of several cation channels, LOE 908 MS, on acute ischemic lesion development with diffusion-weighted magnetic resonance imaging (DWI) and on cerebral perfusion with perfusion imaging (PI) in vivo and on cerebral infarct size using 2,3,5-triphenyltetrazolium chloride (TTC) staining postmortem. A total of 18 male Sprague-Dawley rats underwent 90 min of middle cerebral artery occlusion (MCAO) and were randomly and blindly assigned to either LOE 908 MS or vehicle starting 30 min after inducing focal ischemia and continuing for 4 h. Whole-brain DWI and multislice PI were done before initiation of treatment and repeated frequently for the next 3.5 h. DWI-derived lesion volume at 4 h showed a significant difference in favor of the drug treated group (P=0.03), whereas PI-derived perfusion deficit volumes did not significantly differ between the groups. The postmortem infarct volume at 24 h was significantly attenuated in the treated group in comparison to controls (P=0.0001) and neurological score was significantly better in the treated group (P<0.02). Blocking several distinct cation channels with LOE 908 MS significantly reduced infarct size and improved neurological outcome without observable adverse effects in this focal ischemia model.

Broad-spectrum cation channel inhibition by LOE 908 MS reduces infarct volume in vivo and postmortem in focal cerebral ischemia in the rat.

Cation channels conduct calcium, sodium, and potassium, cations that are likely deleterious in the evolution of focal ischemic injury. Diffusion-weighted magnetic resonance imaging (DWI) is a powerful tool for evaluation of acute cerebral ischemia. We studied the effects of a novel, broad-spectrum inhibitor of several cation channels, LOE 908 MS, on acute ischemic lesion development with DWI and on cerebral infarct size using 2,3,5-triphenyltetrazolium chloride (TTC) staining postmortem. Eighteen male Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAO) and were randomly and blindly assigned to either LOE 908 MS (1 mg/kg bolus 30 min after MCAO and continuous i.v. infusion of 10 mg/kg for 4 h thereafter) or vehicle. Whole-brain DWI was done before initiation of treatment and repeated every 30 min for the next 3.5 h. The animals were reperfused in the magnetic resonance imaging (MRI) scanner 90 min after MCAO. At 24 h, the animals were killed, and the brains were cut into six 2-mm-thick slices and stained with 2% TTC. Percent hemispheric lesion volume (%HLV) was calculated for each animal. Physiological parameters, body weight, and premature mortality (3 in the placebo group and 1 in the treated group) did not differ between the groups. No hypotension, abnormal behavior, or other adverse effects were seen. Pretreatment, the DWI-derived %HLV did not differ between the groups (19.8 +/- 6.2 in the control group and 17.9 +/- 7.9 in the treated group), whereas at 4 h after MCAO, it was significantly smaller in the treated group (21.8 +/- 15.4 vs 40.4 +/- 15.5, p = 0.03). Postmortem, TTC-derived %HLV was significantly attenuated in the LOE 908 MS group (21.3 +/- 11.9 vs 50.1 +/- 10.7, p = 0.0001) and the neurological scores at 24 h were significantly better among the treated rats (2.1 +/- 1.5 vs 4.0 +/- 1.0, p < 0.02). LOE 908 MS significantly improved neurological outcome and reduced infarct size without observable effects in rats as demonstrated in vivo by DWI and confirmed postmortem by TTC staining. Blocking several distinct cation channels by LOE 908 MS showed significant neuroprotection.

Neuroprotective effects of a novel broad-spectrum cation channel blocker, LOE 908 MS, on experimental focal ischemia: a multispectral study.

Thirty-four rats undergoing 90 minutes of temporary middle cerebral artery occlusion were randomly and blindly assigned to vehicle or (RS)-(3,4-dihydro-6, 7-dimethoxyisoquinoline-1-gamma1)-2-phenyl-N,N-di-2-(2, 3, 4-trimethoxyphenyl)ethyl acetamide (LOE 908 MS; 0.5 mg/kg) i.v. bolus at 30 minutes after arterial occlusion followed by a 5 mg/kg/hr i.v. infusion for 3.8 hours (n =17/group). Perfusion-, diffusion- and T(2)-weighted magnetic resonance imaging was performed before treatment and repeatedly after treatment. Multispectral analysis was used to define ischemic abnormalities. The size of the ischemic abnormalities, including the ischemic core and penumbra, was not different between the two groups before treatment. However, a significant difference in ischemic lesion size was detected beginning 1.5 hours after treatment. The size of the ischemic core was significantly smaller in the treatment group, while the size of the ischemic penumbra was similar in the two groups at 85 minutes after arterial occlusion. Postmortem infarct size at 24 hours was significantly smaller in the drug-treated group than in the placebo group. These results demonstrate that LOE 908 MS can reduce ischemic lesion size, which is probably attributable to inhibition of expansion of the ischemic core. J. Magn. Reson. Imaging 1999;10:138-145.

Determination of focal ischemic lesion volume in the rat brain using multispectral analysis.

Multispectral (MS) analysis was used to determine the ischemic lesion volume in the rat brain after permanent middle cerebral arterial occlusion. MS analysis used a four-dimensional MS model consisting of an estimate of the average apparent diffusion coefficient of water (ADC(av)), T2, proton density, and perfusion. Four classification methods were investigated: (a) multivariate gaussian (MVG); (b) k-nearest neighbor (k-NN); (c) k-means (KM); and (d) fuzzy c-means (FCM). MVG and k-NN classifiers are supervised methods requiring labeled training data to characterize the stroke lesion. Unsupervised classifiers (KM, FCM) do not require previous statistics or labeled training data, resulting in potentially greater clinical usefulness. All MS methods provided significant correlation with postmortem findings beyond the use of ADC(av) alone (partial correlation given the ADC(av) estimate: MVG, .66; k-NN, .75; KM, .68; FCM, .70). This study demonstrates that MS analysis provides an improved estimate of ischemic lesion volume over that obtained from ADC alone.

Delayed treatment with an adenosine kinase inhibitor, GP683, attenuates infarct size in rats with temporary middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Brain ischemia is associated with a marked increase in extracellular adenosine levels. This results in activation of cell surface adenosine receptors and some degree of neuroprotection. Adenosine kinase is a key enzyme controlling adenosine metabolism. Inhibition of this enzyme enhances the levels of endogenous brain adenosine already elevated as a result of the ischemic episode. We studied a novel adenosine kinase inhibitor (AKI), GP683, in a rat focal ischemia model. METHODS: Four groups of 10 adult Sprague-Dawley rats were exposed to 90 minutes of temporary middle cerebral artery (MCA) occlusion. Animals were injected intraperitoneally with vehicle, 0.5 mg/kg, 1.0 mg/kg, or 2.0 mg/kg of GP683 30, 150, and 270 minutes after the induction of ischemia by a researcher blinded to treatment group. The animals were euthanatized 24 hours after MCA occlusion, and brains were stained with 2,3,5-triphenyltetrazolium chloride. We measured brain temperatures in a separate group of 6 rats before and after administration of 1.0 mg/kg GP683. RESULTS: All treated groups showed a reduction in infarct volumes, but a significant effect was observed only in the 1.0 mg/kg-dose group (44% reduction, P=0.0077). Body weight, physiological parameters, neurological scores, and mortality did not differ among the 4 groups. No apparent behavioral side effects were observed. Brain temperatures did not change after drug injection. CONCLUSIONS: Our results indicate that the use of AKIs offers therapeutic potential and may represent a novel approach to the treatment of acute brain ischemia. The therapeutic effect observed was not caused by a decrease in brain temperature.

A new method to improve in-bore middle cerebral artery occlusion in rats: demonstration with diffusion- and perfusion-weighted imaging.

BACKGROUND AND PURPOSE: In-bore middle cerebral artery occlusion (MCAO) enables investigators to acquire preischemic MRI data and to image ischemic changes immediately after occlusion. We have developed a highly successful in-bore MCAO method. This study describes the methods and pertinent techniques. METHODS: Sixty-seven Sprague-Dawley rats were subjected to temporary (n=36) or permanent (n=31) MCAO. The occluding device consisted of a supporting tubing, a driving line, and a silicone-coated 4-0 nylon suture occluder. Outside the magnet, the occluder was positioned in the carotid canal. MCAO was achieved in the magnet bore by remotely advancing the driving line until resistance was felt. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) were acquired before and immediately after occlusion and were used to document the presence of MCAO. RESULTS: Fifty-nine (88.1%) rats were successfully occluded, demonstrating hyperintensity on DWI, perfusion deficits on PWI, and no subarachnoid hemorrhage at postmortem examination. The average values of the apparent diffusion coefficient in both the frontoparietal cortex and the lateral caudoputamen significantly decreased as early as 3 minutes after the onset of ischemia. The failures included preocclusion damage (1/67), sliding out of the occluder during occlusion (1/67), no occlusion (2/67), and arterial perforation (4/67). CONCLUSIONS: Our in-bore MCAO method is easily performed and is as successful as MCAO induced outside the magnet.

Efficacy of intra-arterial and intravenous prourokinase in an embolic stroke model evaluated by diffusion-perfusion magnetic resonance imaging.

OBJECTIVE: To explore the utility of intravenous (i.v.) prourokinase treatment, we compared intra-arterial (i.a.) and i.v. delivery in a rat embolic stroke model, using diffusion (DWI) and perfusion (PI) magnetic resonance imaging to assess in vivo effects on ischemic lesion evolution and reperfusion. BACKGROUND: Thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) for acute ischemic stroke is useful during the initial hours after onset. Prourokinase is a novel thrombolytic agent with potential safety advantages in comparison to rt-PA. METHODS: Twenty-four male Sprague-Dawley rats were embolized with autologous blood clots into the middle cerebral artery territory and then randomly assigned at 30 minutes after embolization to a 2-hour bolus infusion with i.a. prourokinase, i.v. prourokinase, or vehicle. DWI and PI were performed before treatment and repeated during and at the end of the treatment. RESULTS: PI demonstrated that both i.a. and i.v. significantly improved the percentage of the ischemic hemisphere that was normally perfused when the 20-minute, pretreatment, and 145-minute after embolization time points were compared; in the control group, the hypoperfused volume increased over time. DWI disclosed that the ischemic lesion evolution slightly decreased in the i.a. group, remained stable in the i.v. group, and increased over time in the control group. Infarct volume by triphenyltetrazolium chloride (TTC) staining was significantly smaller in both treatment groups than controls. CONCLUSIONS: These results demonstrate that i.a. and i.v. therapy with prourokinase are equally effective in promoting reperfusion and inhibiting the development of focal ischemic injury in this rat embolic stroke model.

A novel endothelin antagonist, A-127722, attenuates ischemic lesion size in rats with temporary middle cerebral artery occlusion: a diffusion and perfusion MRI study.

BACKGROUND AND PURPOSE: Endothelins (ETs) are potent vasoconstrictors. Plasma ET levels increase during acute brain ischemia and may worsen the ischemic damage. Diffusion-weighted MRI (DWI) and perfusion imaging (PI) are powerful tools for evaluation of acute cerebral ischemia. We studied the effects of A-127722, a novel ET(A)-selective ET antagonist, on cerebral ischemic lesion size using 2,3,5-triphenyltetrazolium chloride (TTC) staining postmortem, on acute ischemic lesion development with DWI, and on the cerebral circulation using PI. METHODS: Twenty male Sprague-Dawley rats received either 5 mg/kg of A-127722 or vehicle (n=10 per group) intravenously 30 minutes and subcutaneously 4 hours after middle cerebral artery occlusion (MCAO). Whole-brain DWI and single-slice PI were done before initiation of treatment and repeated frequently thereafter up to 4 hours after MCAO. The animals were reperfused in the MRI scanner 90 minutes after the onset of MCAO. At 24 hours the animals were killed, and the brains were cut into six 2-mm-thick slices and stained with 2% TTC. Percent hemispheric lesion volume (%HLV) was calculated for each animal. RESULTS: Physiological parameters, body weight, neurological scores, and premature mortality (2 versus 2) did not differ between the two groups. No hypotension, abnormal behavior, or other adverse effects were seen. TTC-derived %HLV was 25.3+/-5.6% for controls and 16.2+/-9.6% for treated animals (36% reduction, P<.02). Six animals in each group had successful reperfusion as shown by PI. Among these animals, %HLV was 23.2+/-3.1% for controls and 9.3+/-4.4% for treated animals (60% reduction, P=.0001). The beneficial effect of A-127722 was limited to animals in which successful reperfusion was demonstrated. No difference in PI-detected perfusion deficit size was observed between the groups. DWI did not demonstrate significant in vivo lesion size differences. CONCLUSIONS: A-127722 significantly reduced ischemic lesion size in rats without observable adverse effects. It is not clear whether the effect was due to vasodilatation of collateral arterioles not detectable by PI or whether A-127722 has neuroprotective properties that are independent of vascular effects.

Glycine site antagonist attenuates infarct size in experimental focal ischemia. Postmortem and diffusion mapping studies.

BACKGROUND AND PURPOSE: The glycine site on the N-methyl-D-aspartate (NMDA) receptor complex offers a therapeutic target for acute focal ischemia, potentially devoid of most side effects associated with competitive and noncompetitive NMDA antagonists. METHODS: A novel glycine receptor antagonist, ZD9379, was studied in 70 Sprague-Dawley rats using the suture occlusion model of permanent middle cerebral artery occlusion (MCAO). In the first experiment, 20 rats received an initial bolus of vehicle or 10 mg/kg ZD9379 (n = 10 in each group) 30 minutes after MCAO, followed by a continuous infusion of the same dose per hour for 4 hours. Diffusion-weighted MRI with echo-planar acquisition was used to generate maps of the apparent diffusion coefficient (ADC) of water. In a second experiment, 50 rats were assigned to five groups: vehicle and 10, 5, 2.5, and 1 mg/kg ZD9379 (n = 10 in each group) with the same dosing protocol but no imaging. In both experiments, infarct volume was determined by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: In the first experiment, before therapy was begun, there was no significant difference in ADC-derived ischemic lesion volume between the two groups. Over time, the 10-mg/kg ZD9379-treated rats had a significant delayed regional recovery of reduced ADC values in the peripheral parietal cortex (P = .0156). Postmortem corrected infarct volume at 24 hours after MCAO was significantly smaller in the group treated with 10 mg/kg ZD9379 than in the vehicle group (119.2 +/- 52.2 versus 211.2 +/- 50.0 mm3 [mean +/- SD]; P = .0008; a reduction of 43.6%). In the second experiment, postmortem corrected infarct volumes in rats receiving 10, 5, and 2.5 mg/kg ZD9379 were significantly smaller than in those receiving vehicle, a reduction of 42.6%, 51.4%, and 42.9%, respectively (P = .0001). CONCLUSIONS: This study demonstrates that 2.5- to 10-mg/kg doses of ZD9379 initiated 30 minutes after MCAO significantly reduced infarct size. Diffusion mapping disclosed a delayed treatment effect of this glycine antagonist in focal ischemia, confirmed by the postmortem study.

Effect of basic fibroblast growth factor on experimental focal ischemia studied by diffusion-weighted and perfusion imaging.

BACKGROUND AND PURPOSE: Basic fibroblast growth factor (bFGF) has documented neuroprotective properties. This study was performed to evaluate the effects of bFGF on infarct size when administered 30 minutes after induction of focal cerebral ischemia in rats. Diffusion-weighted and perfusion MRI were used during the drug infusion. METHODS: We blindly randomized 20 Sprague-Dawley rats to receive either drug (n = 10) or vehicle (n = 10). The animals underwent middle cerebral artery (MCA) occlusion using the suture model. Diffusion-weighted MRI was initiated 30 minutes after induction of ischemia and repeated frequently for 3.5 hours. Drug (45 micrograms/kg per hour) or vehicle (saline) infusion began 30 minutes after MCA occlusion and continued for 3 hours. Perfusion images were made at 25, 90, and 150 minutes after MCA occlusion. The animals were killed after 24 hours of permanent MCA occlusion, and brains were stained with 2,3,5-triphenyltetrazolium chloride (TTC). RESULTS: The TTC-derived, corrected infarct volume postmortem in the bFGF-treated group was significantly smaller than that in controls (126.6 +/- 51.9 versus 180.2 +/- 54.9 mm3, mean +/- SD, P = .038). Diffusion imaging showed essentially equal lesion volumes 3 hours after MCA occlusion (195.4 +/- 61 mm3 in the drug-treated group and 194.4 +/- 65 mm3 in controls). At 4 hours, ischemic lesion size was 182.1 +/- 56.9 mm3 in treated animals and 222.9 +/- 88.7 mm3 in the controls (P = .24, NS). Perfusion imaging did not show a change of cerebral perfusion within ischemic brain regions in the bFGF group during the infusion. No behavioral or physiological side effects were observed. CONCLUSIONS: bFGF is a safe and effective treatment for focal cerebral ischemia in rats. We observed a modest delayed difference of ischemic lesion size in vivo with diffusion MRI. The diffusion-weighted MRI findings suggest a potential delayed therapeutic effect of bFGF, and the perfusion imaging findings imply that the effect is not due to increased blood flow to the ischemic region.

The role of spreading depression in focal ischemia evaluated by diffusion mapping.

This study investigated the role of spontaneous and induced spreading depression (SD) on the evolution of focal ischemia in vivo. We induced focal ischemia in 12 rats using the middle cerebral artery suture occlusion (MCAO) method. Chemical stimulation of nonischemic ipsilateral cortex by potassium chloride application (KCl group; n = 7) and saline (NaCl group; n = 5) was performed at 15, 30, 45, and 60 minutes following MCAO, and SD was detected electrophysiologically. Ischemic lesion volumes assessed over 15-minute intervals, evaluated by continuous apparent diffusion coefficient (ADC) of water mapping, demonstrated that the ischemic region increased significantly during 15-minute time epochs with a single SD episode (36.5 +/- 12.9 mm3, mean +/- SD) or multiple SD episodes (39.8 +/- 22.3) compared with those without SD (13.9 +/- 11.5) (p = 0.0009). Infarct volume at postmortem 24 hours after MCAO was significantly larger in the KCl group, with more total SDs (237.8 +/- 13.8) than the NaCl group (190.5 +/- 12.6) (p = 0.0001). This study demonstrates that ischemia-related and induced SDs increase significantly ischemic lesion volume in vivo, supporting the hypothesis for a causative role of SD in extending focal ischemic injury.