DWIBS can be used for the detection of malignant tumors or benign tumors; however, it may be difficult to differentiate between benign and malignant lesions by ADC.

At appropriate concentrations, blueberry juice has the potential to be an effective oral contrast agent for MR imaging.

No abstract

The aim of this study was to compare 2-dimensional (2D) and 3-dimensional (3D) dynamic PET for the absolute quantification of myocardial blood flow (MBF) with 13 N-ammonia ( 13 N-NH 3 ). Methods: 2D and 3D MBF measurements were collected from 21 patients undergoing cardiac evaluation at rest (n 5 14) and during standard adenosine stress (n 5 7). A lutetium yttrium oxyorthosilicate-based PET/CT system with retractable septa, enabling the sequential acquisition of 2D and 3D images within the same patient and study, was used. All 2D studies were performed by injecting 700-900 MBq of 13 N-NH 3 . For 14 patients, 3D studies were performed with the same injected 13 N-NH 3 dose as that used in 2D studies. For the remaining 7 patients, 3D images were acquired with a lower dose of 13 N-NH 3 , that is, 500 MBq. 2D images reconstructed by use of filtered backprojection (FBP) provided the reference standard for MBF measurements. 3D images were reconstructed by use of Fourier rebinning (FORE) with FBP (FORE-FBP), FORE with orderedsubsets expectation maximization (FORE-OSEM), and a reprojection algorithm (RP). Results: Global MBF measurements derived from 3D PET with FORE-FBP (r 5 0.97), FORE-OSEM (r 5 0.97), and RP (r 5 0.97) were well correlated with those derived from 2D FBP (all Ps , 0.0001). The mean 6 SD differences in global MBF measurements between 3D FORE-FBP and 2D FBP and between 3D FORE-OSEM and 2D FBP were 0.01 6 0.14 and 0.01 6 0.15 mL/min/g, respectively. The mean 6 SD difference in global MBF measurements between 3D RP and 2D FBP was 0.00 6 0.16 mL/min/g. The best correlation between 2D PET and 3D PET performed with the lower injected activity was found for the 3D FORE-FBP reconstruction algorithm (r 5 0.95, P , 0.001). Conclusion: For this scanner type, quantitative measurements of MBF with 3D PET and 13 N-NH 3 were in excellent agreement with those obtained with the 2D technique, even when a lower activity was injected. The assessment of quantitative regional myocardial blood flow (MBF) and coronary flow reserve with 13 Nammonia ( 13 N-NH 3 ) has been well established for 2-dimensional (2D) PET (1-4). Recently, there has been growing interest in the use of PET and PET/CT scanners that operate only in the 3-dimensional (3D) mode (5). The main advantage of the 3D mode (with septa retracted) of data acquisition is that its sensitivity is higher than that of the conventional 2D mode (septa extended) (6,7). The increased counting rate in the 3D acquisition mode, however, comes at the cost of increased scatter, number of random events, and dead time compared with those observed in the 2D mode (8). Although the use of 3D PET has demonstrated significant advantages over the use of 2D PET for brain imaging (9-11), the relative benefits of 3D PET for whole-body oncology (12) and cardiac applications are less clear. Previous experimental animal and clinical comparisons of 2D and 3D PET performance for myocardial perfusion imaging with 13 N-NH 3 , 15 O-H 2 O, and 82 Rb showed either a disadvantage for 3D PET (13) or ima...

lthough the heart preferentially uses long-chain fatty acids (LCFAs) as its main energy substrate, alteration in LCFA utilization is well known in pathological hearts 1 and in such cases, assessment of the LCFA metabolism is of clinical importance in determining etiology and developing therapeutic strategies.LCFA metabolism in the heart has been clinically evaluated by scintigraphy using iodine-123-15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (BMIPP), a radioactive LCFA analog. Regional defects of myocardial LCFA uptake are often revealed in patients with coronary artery disease 2-5 and have been interpreted as follows: (1) dissociation between BMIPP and flow-tracer activity (ie, reduced BMIPP uptake but less reduced flow-tracer accumulation) may indicate ischemic but still viable myocardium (ie, the 'mismatch of blood flow and metabolism'); or (2) diminished accumulation of BMIPP together with reduced flowtracer radioactivity related to necrotic or fibrotic tissue.However, despite the increase of flow tracer accumulation in the heart, defects of BMIPP uptake have been noticed in patients with hypertrophic cardiomyopathy and interestingly, an almost negative depiction of the heart by BMIPP scintigraphy has been occasionally observed in patients without discernible defects of coronary perfusion. [6][7][8] The underlying mechanism of this discrepancy (ie, decreased uptake of LCFA in the heart despite rather increased uptake of flow-tracer) has not been fully elucidated. Circulation Journal Vol.66, September 2002The first step of cellular LCFA metabolism is a transverse process of LCFA in the plasma membrane. Although this process is still in dispute, several lines of evidence suggest a protein-mediated process in addition to a simple diffusive process. Among the putative proteins involved, CD36 is a potential candidate. [8][9][10][11] In fact, CD36 knock-out mice have severe defects of LCFA uptake in the heart, 10 and homozygous and compound heterozygous mutation of the CD36 gene (hereafter referred to as CD36 -/-) in humans also causes severe defects of myocardial LCFA uptake, with an almost negative depiction of the heart by BMIPP scintigraphy. 8 In addition to the effects of CD36 -/-on the LCFA uptake in the heart, CD36 -/-resulted in a lack of CD36 expression in platelets and monocytes, referred to as type I CD36 deficiency. 12 We recently found a strong association between the genotype in the coding region of CD36 and the expression level of CD36. Heterozygous mutations in the coding region of this gene (hereafter referred to as CD36 +/-) resulted in the reduced expression of CD36 in monocytes, approximately half that observed in the wild-type gene (hereafter referred to as WT). 13 Accordingly, we hypothesized that not only CD36 -/-but also CD36 +/-might lead to the defects of LCFA uptake in the heart.The effects of CD36 -/-on the LCFA uptake in the heart have been characterized, so far, only qualitatively; that is, an almost negative depiction of the heart by BMIPP scintigraphy. The quantitative evaluat...