MR perfusion imaging

Benner T, Reimer P, Erb G et al (2000) Cerebral MR perfusion imaging first clinical application of a 1 M gadolinium che-... 

Low Risk. CTA has a lower rate of patient discomfort, is less expensive, and has considerably lower risk of stroke and other vascular complications compared to conventional catheter angiography. It is also advantageous in situations when MR is contraindicated or cannot be performed. CTA is typically more readily available than MR, especially in emergency settings. CTA, unlike MRA, lends itself to the imaging of acutely ill patients, as there are no restrictions on the type and quantity of associated support equipment, such as intravenous pumps, ventilators, or monitoring hardware. Because CT scan acquisition is more rapid than that of MRA, CTA is less prone to motion artifact. When CTA is combined with CT perfusion (CTP) for the evaluation of acute stroke, quantitative perfusion data can also be obtained, which is not typically possible with MR perfusion imaging. 

Schaefer, RW, et al., Quantitative assessment of core/pen-umbra mismatch in acute stroke CT and MR perfusion imaging are strongly correlated when sufficient brain volume is imaged. Stroke, 2008. 39(11) p. 2986-92. 

Contrast echocardiography and MR perfusion imaging are probably too sensitive and remain positive in the majority of patients even after successful occlusion of all angiographically visible PAVMs [37,47]. 

Ohno Y, Hatabu H, Takenaka D, Adachi S, Hirota S, Sug-imura K (2002) contrast-enhanced MR perfusion imaging and MR angiography utility for management of pulmonary arteriovenous malformations for embolotherapy. Eur J Radiol 41 136-146... 

Acquisition of MR perfusion images and contrast-enhanced MR angiography in acute ischaemic stroke patients which procedure should be done first Br J Radiol 79 962-967... 

Fig. 21.4. Comparative CT and MR images in a patient after cardiac transplant, with suspicion of an atrial mass. Plain and postcontrast Tl-weighted images demonstrate a mass (arrow) at the posterior wall, which is also shown by contrast-enhanced CT. Dynamic MR perfusion imaging prove the lack of contrast enhancement consistent with a partially calcified atrial thrombus...

CT may be able to demonstrate those collateralized territories, it cannot provide further information on the quahty of collateral blood flow (Fig. 21.8). MR perfusion imaging can prove whether collateral blood flow is sufficient or insufficient (Fig. 21.9). In cases of recurrence of chest pain in patients post-CABG, CT bypass CTA is perfectly suited to assess bypass graft patency (Fig. 21.10) the judgment of the native vessels though is substantially hampered by the fact that coronary vessels may exhibit an accelerated atherosclerosis and calcification. In addition, CTA is limited in its accuracy in small distal coronary segments. Early after CABG, CT assessment of bypass patency may be of clinical value. 

The primary goal of noninvasive imaging tools in this patient population is the assessment of myocardial blood supply, which can be readily assessed by application of MR perfusion imaging. In combination with DE imaging and cine MRI, a comprehensive assessment of patient status is feasible including the extent of reversible perfusion deficits, the extent of infarcted myocardium, and the overall functional status (Fig. 21.11). 

Mashayekh A, Pham DL, Yousem DM, Dizon M, Barker PB, Lin DD (2011) Effects of Ginkgo biloba on cerebral blood flow assessed by quantitative MR perfusion imaging a pilot study. Neuroradiology 53(3) 185-191. doi 10.1007/s00234-010-0790-6... 

Johkoh T, Muller NL, Kavanagh PV et al. Scintigraphic and MR perfusion imaging in preoperative evaluation for lung volume reduction surgery pilot study results. Radiat Med 2000 18 277 281. 

Liu YJ, Chen CY, Chung HW, Huang IJ, Lee CS, Chin SC, Liou M (2003) Neuronal damage after ischemic injury in the middle cerebral arterial territory deep watershed versus territorial infarction at MR perfusion and spectroscopic imaging. Radiology 229 366-374... 

Tombach B, Benner T, Reimer P et al (2003) Do highly concentrated gadolinium chelates improve MR brain perfusion imaging Intraindividually controlled randomized... 

Kwong KK, Chesler DA Weisskoff RM, Donahue KM, Davis TL, Ostergaard L, Campbell TA, Rosen BR (1995) MR perfusion studies with Tl-weighted echo planar imaging. Magn Reson Med 34 878-887. 

Schaefer PW, Ozsunar Y, He J, Hamberg LM, Hunter GJ, Sorensen AG, Koroshetz WJ, Gonzalez RG. Assessing tissue viability with mr diffusion and perfusion imaging. AJNR Am J Neuroradiol. 2003 24 436-443... 

The apphcation of CTP was first proposed as early as 1980 by Axel [20] however, the acquisition and processing systems available in the 1980s were too slow to make CTP a practical tool. The general principles underlying the computation of perfusion parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (M lT) are the same for both MR and CT the overall clinical applicability of perfusion imaging using both of these modalities is likely to be similar, hi addition, as will be discussed, first pass CTP, unlike... 

Table 5.5 Advantages and disadvantages of CTP relative to MR perfusion weighted imaging (PWI)...

Fig. 5.9 Prediction of infarct growth. A 65-year-old man, improving clinically at 5 h postictus, was monitored in the Neurology ICU based on his labile blood pressure, a fixed left M2 occlusion on CTA, and a significant core/penumbra mismatch on CTP/MRP. His 24-h follow-up DWI showed a small infarction. However, 24 h after cessation of hypertensive therapy there was infarct growth into the region of penumbra. Admission CTA (top) CTP (CBV/CBF/ MTT) at 4.5 h second row) MR-perfusion weighted imaging (MR-PWI) (CBV/CBF/MTT) at 5.25 h (third row) DWI at 24 h (fourth row) and follow-up DWI at 48 h (bottom). The CTP and MR-PWI demonstrate a mismatch between the CBV (no abnormality) and the CBF/MTT penumbra (arrows). After cessation of hypertensive therapy, the DWI abnormahty grows into the region predicted by the CBF/MTT maps...

Berzin, T, et al., CT perfusion imaging versus MR diffusion weighted imaging prediction of final infarct size in hyperacute stroke [abstract]. Stroke, 2001. 32 p. 317. 

Aksoy, F.G. and M.H. Lev, Dynamic contrast-enhanced brain perfusion imaging technique and clinical applications. Semin Ultrasound CT MR, 2000. 21(6) p. 462-77. 

Eastwood, J.D., et al.. Correlation of early dynamic CT perfusion imaging with whole-brain MR diffusion and perfusion imaging in acute hemispheric stroke. AINR Am 1 Neuroradiol, 2003. 24(9) p. 1869-75. 

Wu O, 0stergaard L, Koroshetz WJ, Schwamm LH, O Donnell J, Schaefer PW, Rosen BR, Weisskoff RM, Sorensen AG. Effects of tracer arrival time on flow estimates in mr perfusion-weighted imaging. Magn Reson Med. 2003 50 856-864... 

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