Interobserver Reliability on Intravoxel Incoherent Motion Imaging in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Noninvasive perfusion-weighted imaging with short scanning time could be advantageous in order to determine presumed penumbral regions and subsequent treatment strategy for acute ischemic stroke (AIS). Our aim was to evaluate interobserver agreement and the clinical utility of intravoxel incoherent motion MR imaging in patients with acute ischemic stroke.

MATERIALS AND METHODS

We retrospectively studied 29 patients with AIS (17 men, 12 women; mean age, 75.2 [SD, 12.0 ] years; median, 77 years). Each patient underwent intravoxel incoherent motion MR imaging using a 1.5T MR imaging scanner. Diffusion-sensitizing gradients were applied sequentially in the x, y, and z directions with 6 different b-values (0, 50, 100, 150, 200, and 1000 seconds/mm²). From the intravoxel incoherent motion MR imaging data, diffusion coefficient, perfusion fraction, and pseudodiffusion coefficient maps were obtained using a 2-step fitting algorithm based on the Levenberg-Marquardt method. The presence of decreases in the intravoxel incoherent motion perfusion fraction and pseudodiffusion coefficient values compared with the contralateral normal-appearing brain was graded on a 2-point scale by 2 independent neuroradiologists. Interobserver agreement on the rating scale was evaluated using the κ statistic. Clinical characteristics of patients with a nondecreased intravoxel incoherent motion perfusion fraction and/or pseudodiffusion coefficient rated by the 2 observers were also assessed.

RESULTS

Interobserver agreement was shown for the intravoxel incoherent motion perfusion fraction (κ = 0.854) and pseudodiffusion coefficient (κ = 0.789) maps, which indicated almost perfect and substantial agreement, respectively. Patients with a nondecreased intravoxel incoherent motion perfusion fraction tended to show recanalization of the occluded intracranial arteries more frequently than patients with a decreased intravoxel incoherent motion perfusion fraction.

CONCLUSIONS

Intravoxel incoherent motion MR imaging could be performed in < 1 minute in addition to routine DWI. Intravoxel incoherent motion parameters noninvasively provide feasible, qualitative perfusion-related information for assessing patients with acute ischemic stroke.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 1: Hemodynamic effects in normal dogs and dogs with acute heart failure

Cardiovascular effects of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine), a calcium channel blocker, were investigated in anesthetized normal dogs and dogs with acute heart failure (AHF), and compared with those of nitroglycerin (NTG). In open-chest anesthetized dogs, NIC (0.1-10 micrograms/kg/min i.v.) dose-dependently increased cardiac output (CO) and coronary blood flow as well as decreased mean blood pressure (MBP). NIC had no effect on heart rate (HR) or maximum rate of rise of left ventricular pressure (max. dp/dt). In contrast (0.1-10 micrograms/kg/min i.v.) decreased MBP, but did not change the other cardiovascular parameters. NIC and NTG did not prolong PQ, QRS or QTc intervals. In addition, NIC was effective in the presence of dobutamine. In the anesthetized dog model of ischemic AHF induced by coronary ligation, and ischemia/angiotensin II-induced AHF, NIC (1 and 3 micrograms/kg/min i.v.) increased CO and stroke volume, and reduced total peripheral resistance without decreasing HR or cardiac contractility. Furthermore, in the ischemia/angiotension II-induced AHF model, NIC decreased left ventricular end-diastolic pressure (LVEDP). In contrast, NTG (1-10 micrograms/kg/min i.v.) decreased LVEDP in both AHF models; but did not increase CO. These results suggest that NIC improves hemodynamics in dogs with AHF mainly by reducing afterload without adversely affecting the cardiac contractility or conduction system, while NTG exerts its effect on AHF by reducing preload. NIC injection would thus appear to be beneficial in the treatment of AHF.

Pharmacological profile of nicardipine hydrochloride in anesthetized dogs with acute heart failure. Part 2: Effect on myocardial metabolism

The effect of nicardipine hydrochloride (NIC, CAS 54527-84-3, Perdipine) on myocardial metabolism was investigated in an experimental model of ischemic acute heart failure (AHF) induced by coronary ligation in anesthetized dogs. The left anterior descending and/or circumflex coronary ligation decreased coronary sinus blood flow (CBF), maximum rate of rise of left ventricular pressure (max. dp/dt), cardiac output (CO) and stroke volume (SV), and increased left ventricular end-diastolic pressure, indicating the development of AHF. In this ischemic AHF model, NIC (3 micrograms/kg/min i.v. infusion for 15 min) increased CBF, CO and SV, and reduced systemic and coronary artery resistances, resulting in the improvement of AHF. During the effective period, NIC decreased myocardial oxygen consumption and the coronary arterio-venous difference of oxygen content, carbon dioxide pressure and pH. At the same time, NIC did not decrease the lactate extraction. These results suggest that NIC improves hemodynamics and the balance of myocardium oxygen supply and demand in dogs with AHF by means of reducing afterload and dilating coronary artery.

Carrier-mediated transport of monocarboxylic acids in primary cultured epithelial cells from rabbit oral mucosa

PURPOSE

Using primary cultured rabbit oral mucosal epithelial cells (ROEpi), we investigated whether carrier-mediated drug absorption via the oral mucosal route occurs.

METHODS

Oral mucosal epithelial cells were isolated from rabbit buccal mucosa and cultured on tissue culture plates. When the cells reached confluence, drug uptake experiments were performed. [14C]Benzoic acid or [14C]acetic acid was used as a marker for monocarboxylic acid carrier-mediated transport.

RESULTS

The uptake of [14C]benzoic acid by ROEpi occurred at a much lower rate at 4 degrees C than at 37 degrees C. The metabolic inhibitors, sodium azide and 2,4-dinitrophenol, significantly inhibited the uptake of [14C]benzoic acid by ROEpi. Various monocarboxylic acids inhibited the uptake of [14C]benzoic acid or [14C]acetic acid by ROEpi, whereas dicarboxylic acids did not affect the uptake. Kinetic analysis using Lineweaver-Burk plots revealed that acetic acid competitively inhibited the uptake of [14C]benzoic acid, and benzoic acid competitively inhibited the uptake of [14C]acetic acid by ROEpi.

CONCLUSIONS

There exists a carrier-mediated transport system for monocarboxylic acids in oral mucosal epithelial cells.