To study the dynamic changes of CT perfusion parameters during the first 12 h in the embolic cerebral ischemia models. Local cerebral ischemia model were established in 7 New Zealand white rabbits. All CT scans were performed with a GE Lightspeed 16 multislice CT. Following the baseline scan, further CT perfusion scans were performed at the same locations 20 min, 1-6 h and 8, 10 and 12 h after the embolus delivery. Maps of all parameters were obtained by CT perfusion software at each time point. The brains, taken 12 h after the scan, were sliced corresponding to the positions of the CT slices and stained by 2,3,5-triphenyltetrazolium chloride (TTC). On the basis of the TTC results, the ischemic sides were divided into 3 regions: core, penumbra and the relatively normal region. The changes of all parameters were then divided into 3 stages. In the first two hours (the first stage), the CBV dropped more remarkably in the core than in the penumbra but rose slightly in the relatively normal region while the CBF decreased and MTT, TTP extended in all regions to varying degrees. In the 2nd-5th h (the second stage), all the parameters fluctuated slightly around a certain level. In the 5th-12th h (the third stage), the CBV and CBF dropped, and MTT and TTP were prolonged or shortened slightly in the core and penumbra though much notably in the former while the CBV, CBF rose and MTT, TTP were shortened remarkably in the relatively normal region. We experimentally demonstrated that the location and extent of cerebral ischemia could be accurately assessed by CT perfusion imaging. The pathophysiology of the ischemia could be reflected by the CT perfusion to varying degrees.
Blood Flow Velocity ; Brain Ischemia/physiopathology ; Brain Ischemia/*radiography ; Cerebrovascular Circulation ; Stroke/physiopathology ; Tomography, X-Ray Computed

This study was performed to establish an experimental model of ischemia for the investigation of new treatment modality of limb-threatening ischemia. We produced ischemia in the hindlimbs of 8 New Zealand white rabbits. Under general anesthesia, the left femoral artery was exposed, freed, and excised from distal external iliac artery to proximal popliteal and saphenous arteries. And then both hindlimbs were serially examined to assess the ischemia according to the time table until postoperative 6 weeks. We assessed clinical observation, blood pressure, radioisotopic perfusion scan, and angiography. Clinical ischemic changes of the operated feet were observed in 63%. The blood pressure of left calves was measurable on postoperative day 3 (p<0.05, vs preoperative day 2) and then gradually increased to reach a plateau in postoperative week 6. Radioisotopic arterial perfusion showed similar profiles as in blood pressure. Angiography of ischemic hindlimbs demonstrated a few collateral vessels arising from the internal iliac artery with the reconstitution of the posterior tibial artery in postoperative week 2. In postoperative week 6, collaterals remained the same in number. However, these became dilated and tortuous and showed reconstitution in distal hindleg. In conclusion, this is a reproducible, measurable, and economical animal model of hind limb ischemia.
Angiography ; Animal ; Blood Pressure ; *Disease Models, Animal ; Hindlimb/*blood supply ; Ischemia/*physiopathology/radiography ; Male ; Rabbits

Conventional coronary angiography (CAG) has limitations in evaluating lesions producing ischemia. Three dimensional quantitative coronary angiography (3D-QCA) shows reconstructed images of CAG using computer based algorithm, the Cardio-op B system (Paieon Medical, Rosh Ha'ayin, Israel). The aim of this study was to evaluate whether 3D-QCA can reliably predict ischemia assessed by myocardial fractional flow reserve (FFR) < 0.80. 3D-QCA images were reconstructed from CAG which also were evaluated with FFR to assess ischemia. Minimal luminal diameter (MLD), percent diameter stenosis (%DS), minimal luminal area (MLA), and percent area stenosis (%AS) were obtained. The results of 3D-QCA and FFR were compared. A total of 266 patients was enrolled for the present study. FFR for all lesions ranged from 0.57 to 1.00 (0.85 +/- 0.09). Measurement of MLD, %DS, MLA, and %AS all were significantly correlated with FFR (r = 0.569, 0609, 0.569, 0.670, respectively, all P < 0.001). In lesions with MLA < 4.0 mm2, %AS of more than 65.5% had a 80% sensitivity and a 83% specificity to predict FFR < 0.80 (area under curve, AUC was 0.878). 3D-QCA can reliably predict coronary lesions producing ischemia and may be used to guide therapeutic approach for coronary artery disease.
Aged ; Coronary Angiography/*methods ; Coronary Circulation ; Coronary Stenosis/etiology/*physiopathology/*radiography ; Female ; *Fractional Flow Reserve, Myocardial ; Humans ; Imaging, Three-Dimensional/*methods ; Male ; Myocardial Ischemia/complications/physiopathology/*radiography ; Radiographic Image Enhancement/methods ; Radiographic Image Interpretation, Computer-Assisted/methods ; Reproducibility of Results ; Sensitivity and Specificity

To assess the regional cerebral blood flow (rCBF) in ischemic stroke, we analyzed the findings of single photon emission computed tomography (SPECT) using technetium-99m hexamethyl propyleneamine oxime (Tc-99m HMPAO). The SPECT images revealed abnormal areas of decreased perfusion in 29 out of 31 subjects (93.5%), which represented a higher detection rate than those for CT and MR (89.5%, respectively). Also, the areas of decreased perfusion were frequently larger than the lesions on CT and MR. Areas of decreased perfusion remote from the CT/MR lesions were found in 10 patients, including 8 with crossed cerebellar diaschisis (CCD). Thus, studies of rCBF by Tc-99m HMPAO SPECT can be useful in the assessment of ischemic stroke.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Brain Ischemia/*physiopathology/radiography/radionuclide imaging ; Cerebrovascular Circulation/*physiology ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Regional Blood Flow ; Tomography, Emission-Computed, Single-Photon ; Tomography, X-Ray Computed

The regional cerebral blood flow of four patients with delayed carbon monoxide sequelae and four age matched controls was measured, using a xenon inhalation CT scan (GE 9800). Variable patterns of decreased cerebral blood perfusion according to the clinical state of the patient were noted among the patients. Follow up studies, 2 months later, indicated that there was a correlation between the fluctuation of symptoms and the changes in regional cerebral blood flow. It is suggested that the impairment of cerebral perfusion may play a critical role in delayed carbon monoxide sequelae.
Administration, Inhalation ; Aged ; Brain/*blood supply ; Brain Ischemia/chemically induced/physiopathology/*radiography ; Carbon Monoxide Poisoning/*complications ; Case Report ; Female ; Human ; Male ; Middle Age ; Regional Blood Flow/drug effects ; Support, Non-U.S. Gov't ; Time Factors ; Tomography, X-Ray Computed ; Xenon/administration and dosage/diagnostic use

We report on a case of ischemic dysfunction of the sinus node as a complication after percutaneous transluminal coronary angioplasty of the distal left circumflex artery. After local thrombolytic therapy in the sinus node artery, sinus node arterial flow was re-established and sinus node function normalized over the period of a week. Our experience suggests that immediate reperfusion of a totally occluded nodal artery can be re-established. Ischemic dysfunction of the sinus node, as a complication of angioplasty, is generally transient and requires a prolonged period for recovery. Therefore the decision to implant a permanent pacemaker should be delayed for at least one week after the ischemic insult.
Urinary Plasminogen Activator/administration & dosage/*therapeutic use ; Thrombolytic Therapy/*methods ; Sinoatrial Node/*physiopathology ; Myocardial Ischemia/*complications/radiography/therapy ; Middle Aged ; Male ; Infusions, Intravenous ; Humans ; Follow-Up Studies ; Fibrinolytic Agents/administration & dosage/*therapeutic use ; Electrocardiography ; Coronary Angiography ; Arrhythmia/diagnosis/*drug therapy/etiology ; Angioplasty, Transluminal, Percutaneous Coronary/adverse effects