Dual dynamic contrast-enhanced MR imaging

A method was devised for obtaining dynamic contrast-enhanced T1-weighted and relaxation rate (ΔR2*) images simultaneously to evaluate regional hemodyn-amics of the brain tumors. On a 1.5-T MR system, dual dynamic contrast-enhanced images were obtained using a gradient echo (dual echo fast field echo) pulse sequence with the keyhole technique to improve temporal and spatial resolution during a rapid bolus injection of gadopentetate dimeglumine. The dynamic T1 contrast images were obtained from the first echo; moreover. ∫ ΔR2*dt values were calculated from the first and the second echo images. The dynamic T1 contrast images provided information about characteristic enhancement pattern (vascularization and disruption of bloodbrain barrier), and the f ΔR2*dt values provided a map of regional blood pool in tumor site, peritumoral edema, and other surrounding regions of the brain. The ability to obtain dynamic contrast-enhanced T1 contrast and ΔR2* imaging at the same time allows optimization of the advantages of each and thereby more information about the microvascular circulation of the brain lesions.     

Synovial sarcoma: dynamic contrast-enhanced MR imaging features

Objective. To determine whether previously described so-called malignant dynamic contrast-enhanced magnetic resonance (MR) imaging features – early start, peripheral enhancement and early plateau or washout phase – occur consistently in synovial sarcoma. Design and patients. Dynamic contrast-enhanced MR images of 10 patients with histologically proven synovial sarcoma were reviewed. The start, pattern and progression of tumor enhancement were assessed and correlated with histopathology. Results. In all patients, the time interval between arterial and early tumor enhancement was less than 7 s (mean 4.40 s, SD 2.09 s). Six synovial sarcomas showed enhancement with a subsequent rapidly progressive linear increase in signal intensity followed by a plateau in one lesion and washout in five. Four lesions showed a late sustained increase in enhancement after the initial rapid increase in enhancement. The pattern of initial enhancement was peripheral in only two lesions, diffuse in four and heterogeneous in four lesions. Conclusions. Enhancement of tumor within 7 s after arterial enhancement is, of the three parameters described previously, the only sign that occurs consistently in synovial sarcoma. Received: 2 May 2000 Revision requested: 26 July 2000 Revision received: 19 September 2000 Accepted: 21 September 2000     

Prostate cancer localization with dynamic contrast-enhanced MR imaging and proton MR spectroscopic imaging

PURPOSE: To prospectively determine the accuracies of T2-weighted magnetic resonance (MR) imaging, dynamic contrast material-enhanced MR imaging, and quantitative three-dimensional (3D) proton MR spectroscopic imaging of the entire prostate for prostate cancer localization, with whole-mount histopathologic section findings as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional review board, and informed consent was obtained from all patients. Thirty-four consecutive men with a mean age of 60 years and a mean prostate-specific antigen level of 8 ng/mL were examined. The median biopsy Gleason score was 6. T2-weighted MR imaging, dynamic contrast-enhanced MR imaging, and 3D MR spectroscopic imaging were performed, and on the basis of the image data, two readers with different levels of experience recorded the location of the suspicious peripheral zone and central gland tumor nodules on each of 14 standardized regions of interest (ROIs) in the prostate. The degree of diagnostic confidence for each ROI was recorded on a five-point scale. Localization accuracy and ROI-based receiver operating characteristic (ROC) curves were calculated. RESULTS: For both readers, areas under the ROC curve for T2-weighted MR, dynamic contrast-enhanced MR, and 3D MR spectroscopic imaging were 0.68, 0.91, and 0.80, respectively. Reader accuracy in tumor localization with dynamic contrast-enhanced imaging was significantly better than that with quantitative spectroscopic imaging (P < .01). Reader accuracy in tumor localization with both dynamic contrast-enhanced imaging and spectroscopic imaging was significantly better than that with T2-weighted imaging (P < .01). CONCLUSION: Compared with use of T2-weighted MR imaging, use of dynamic contrast-enhanced MR imaging and 3D MR spectroscopic imaging facilitated significantly improved accuracy in prostate cancer localization.     

肾脏肿瘤的MR动态增强扫描研究

目的:探讨MR动态增强扫描在肾脏肿瘤诊断和鉴别诊断中的价值。方法:对21例肾细胞癌、11例肾错构瘤和6例肾囊肿行MR常规检查及动态增强和延迟增强扫描,测量病灶的信号强度,绘制时间-对比增强率曲线并对动态增强的类型及血液动力学改变进行分析。结果:肾脏肿瘤动态增强后的时间-对比增强率曲线不同,富血供肾癌在早期强化并逐渐上升,但其时间-对比增强率曲线无明显峰值;乏血供肾癌早期轻度强化,缓慢上升至60s后趋于稳定;肾错构瘤早期即明显强化,于30s达到强化高峰后快速下降;肾囊肿则无明显强化。结论:通过定量分析肾脏肿瘤的信号强度,动态增强MRI可以提供肿瘤的血供信息,有助于肾脏肿瘤的诊断和鉴别诊断。     

Polycystic ovary syndrome: dynamic contrast-enhanced ovary MR imaging

OBJECTIVE: to determine the enhancement behaviour of the ovaries in women with polycystic ovary syndrome (PCOS) by dynamic contrast-enhanced magnetic resonance (DCE-MR) imaging and to compare these data with those of normal ovulating controls. METHOD: 24 women with PCOS and 12 controls underwent DCE-MR imaging. Dynamic images were acquired before and after injection of a contrast bolus at 30 s and the min of 1, 2, 3, 4 and 5. On postprocessing examination: (i) the ovarian volumes; (ii) the signal intensity value of each ovary per dynamic study; (iii) early-phase enhancement rate; (iv) time to peak enhancement (T(p)); and (v) percentage of washout of 5th min were determined. Data of the ovaries of the women with PCOS and controls were compared with Mann-Whitney U-test. RESULTS: the mean values of T(p) were found to be significantly lower in women with PCOS than in controls (p < 0.05). On the other hand, the mean values of ovarian volume, the early-phase enhancement rate, and percentage of washout of 5th min of ovaries were significantly higher in PCOS patients (p < 0.05). Examination of the mean signal intensity-time curve revealed the ovaries in women with PCOS showed a faster and greater enhancement and wash-out. CONCLUSION: the enhancement behaviour of ovaries of women with PCOS may be significantly different from those of control subjects on DCE-MR imaging examination. In our experience, it is a valuable modality to highlight the vascularization changes in ovarian stroma with PCOS. We believe that improved DCE-MR imaging techniques may also provide us additional parameters in the diagnosis and treatment strategies of PCOS.     

肝细胞癌在MR扩散加权成像与动态增强成像中的影像表现

信号;2个T1WI平扫等信号的病变,各期增强仍然呈等信号,DWI表现为高信号,其中1个病理证实为再生结节.1个肝硬化再生结节T1WI平扫及DWI均为高信号,动脉期明显强化,门静脉及平衡期为等信号.结论 多数HCC在MR动态增强图像上表现为动脉期明显强化,部分小HCC可表现为等信号.Gd-DTPA动态增强与DWI结合可能有助提高HCC的诊断准确性.     

Assessment of metastatic cervical adenopathy using dynamic contrast-enhanced MR imaging

BACKGROUND AND PURPOSE: Morphologic assessment by conventional imaging methods of lymph node metastases in patients with squamous cell carcinoma of the head and neck is, at best, insensitive. Doppler sonography has shown that lymph node metastases exhibit alterations in the number of vessels and blood flow. We assessed the ability of dynamic contrast-enhanced MR imaging to differentiate normal from diseased nodes in this patient population. METHODS: Twenty-one patients with newly diagnosed squamous cell carcinoma and no previous treatment were studied with the use of a head and neck phased array surface coil. Anatomic imaging included high resolution T1-weighted, fat-saturated fast spin-echo T2-weighted, and contrast-enhanced T1-weighted imaging (0.99-1.32 mm(3) voxels). The dynamic contrast-enhanced MR imaging was performed by using a 2D fast spoiled gradient recalled sequence with single dose bolus injection of contrast agent. Calculated values included time to peak, peak enhancement, maximum slope, and washout slope for the enhancement. All patients underwent neck dissection as part of their indicated treatment, and imaging results were correlated with pathologic findings. RESULTS: Dynamic contrast-enhanced MR imaging and pathology comparisons were obtained for 68 nodes. There was significantly longer time to peak (P <.001), lower peak enhancement (P <.05), lower maximum slope (P <.01), and slower washout slope (P <.05) in the tumor-involved nodes compared with the normal nodes. CONCLUSION: Analysis of dynamic contrast-enhanced MR imaging can differentiate normal from diseased lymph nodes in patients with squamous cell carcinoma of the head and neck.     

The assessment of irradiated bladder carcinoma using dynamic contrast-enhanced MR imaging

AIM: To evaluate the role of dynamic contrast-enhanced magnetic resonance imaging (DCEMRI) in distinguishing residual or recurrent tumour from radiation change in patients with bladder carcinoma.MATERIALS AND METHODS: Forty patients with biopsy proven bladder carcinoma were imaged before and at 4 and 12 months after radiotherapy (XRT) using conventional and dynamic contrast-enhanced magnetic resonance imaging at 0.5 Tesla. An enhancement of >1.54 times above baseline at 80 s post-contrast injection proved a reliable indicator of tumour before radiotherapy and was therefore applied to the assessment of patients after XRT. Conventional MR images and dynamic enhancement profiles (DEPs) from the site of previous tumour were scored by three radiologists for the presence of tumour at 4 and 12 months after XRT. Findings were compared with cystoscopic biopsy.RESULTS: Dynamic contrast-enhanced magnetic resonance imaging had negative predictive values of 100% and 93% for tumour recurrence at 4 and 12 months, respectively. The positive predictive values, sensitivity and specificity were 48, 100 and 48% at 4 months and 50, 80 and +76% at 12 months post XRT, respectively.CONCLUSION: Dynamic contrast-enhanced magnetic resonance imaging may prove reliable in excluding the presence of persistent or recurrent tumour up to 12 months after XRT.     

Intracranial mass lesions: dynamic contrast-enhanced susceptibility-weighted echo-planar perfusion MR imaging

Dynamic contrast agent-enhanced perfusion magnetic resonance (MR) imaging provides physiologic information that complements the anatomic information available with conventional MR imaging. Analysis of dynamic data from perfusion MR imaging, based on tracer kinetic theory, yields quantitative estimates of cerebral blood volume that reflect the underlying microvasculature and angiogenesis. Perfusion MR imaging is a fast and robust imaging technique that is increasingly used as a research tool to help evaluate and understand intracranial disease processes and as a clinical tool to help diagnose, manage, and understand intracranial mass lesions. With the increasing number of applications of perfusion MR imaging, it is important to understand the principles underlying the technique. In this review, the essential underlying physics and methods of dynamic contrast-enhanced susceptibility-weighted echo-planar perfusion MR imaging are described. The clinical applications of cerebral blood volume maps obtained with perfusion MR imaging in the differential diagnosis of intracranial mass lesions, as well as the pitfalls and limitations of the technique, are discussed. Emphasis is on the clinical role of perfusion MR imaging in providing insight into the underlying pathophysiology of cerebral microcirculation.     

Differentiation of hepatic hemangiomas from metastases by dynamic contrast-enhanced MR imaging

Twenty-nine patients with hepatic hemangiomas (n = 14) and hepatic metastases (n = 15) underwent magnetic resonance (MR) imaging prior to and after an intravenous bolus injection of Gd-diethylenetriamine pentaacetic acid (0.2 mmol/kg). Before contrast application, a T2-weighted spin echo sequence (SE 1,600/105) and a T1-weighted gradient echo sequence (GE 315/14/90 degrees pulse angle) were performed. Beginning with injection of the contrast agent, a dynamic study was conducted for 10 min using a moderately T1-weighted gradient echo sequence (GE 40/14/40 degrees) with an acquisition time of 10.2 s per image. Delayed (11 min) and late (60 min) postcontrast images were obtained using a T1-weighted sequence (GE 315/14/90 degrees). In the dynamic study (0-10 min) the hemangiomas were characterized by peripheral contrast enhancement and a subsequent hyperintense fill-in. The metastases showed very mixed patterns of enhancement after contrast administration, and their signal intensity remained low compared with that of the hepatic tissue. In the delayed postcontrast examination (11 min) the hemangiomas had a very high and homogeneous signal intensity and the metastases were characterized by an inhomogeneous, hypointense to isointense signal. The contrast between tumor and liver [signal-difference-to-noise ratio (SD/N)] was higher for all hemangiomas than it was for the metastases. In the T2-weighted precontrast examination, on the other hand, five hemangiomas and seven metastases showed an overlap in the SD/N. The late postcontrast images (60 min) did not yield any further diagnostic information. We conclude that the combination of a dynamic MR study with delayed postcontrast T1-weighted imaging is a useful method of diagnosing hepatic hemangiomas.     

Acute cerebral ischemia: evaluation with dynamic contrast-enhanced MR imaging and MR angiography.

Dynamic contrast-enhanced T2-weighted magnetic resonance (MR) imaging and MR angiography (MRA) were used to evaluate cerebral blood volume and the intracranial arterial system in 34 patients within 48 hours after the onset of cerebral ischemia. In 24 of the patients, an abnormality identified on T2-weighted images corresponded to the acute clinical deficit. Intracranial MRA demonstrated occlusions or severe stenoses of major vessels supplying the area of infarction in 16 of these patients, and decreased blood volume correlated well with MRA abnormalities. Infarcts less than 2 cm in diameter were not reliably shown with MRA or blood volume studies. Correlation between lesions seen with MRA and decreased blood volume in acute infarcts was good, and both techniques demonstrated lesions early in the clinical course. By providing information about hemodynamics not available with conventional T1- or T2-weighted images, MRA and dynamic MR imaging could prove helpful in describing the pathophysiologic characteristics of stroke and in guiding early therapeutic intervention.     

磁共振动态增强、扩散加权成像联合应用对乳腺病变的诊断价值

目的：探讨单一磁共振动态增强扫描诊断试验、扩散加权成像诊断试验及其联合应用对乳腺病变定性诊断的敏感性、特异性和阳性似然比、阴性似然比,比较其诊断效能。方法：对临床拟诊肿块的患者37例,同时进行动态增强扫描和扩散加权成像检查,均获得手术和病理证实,其中良性病灶18个,恶性病灶19个。对病变的边缘、形态特征、动态增强表现及时间一信号强度曲线采用评分法对病变性质分恶性、可疑恶性及良性三组进行判断。参照动态增强病变位置确定扩散图像病变所在,描记扩散图像上病变的感兴趣区,由软件计算获得表观扩散系数（ADC）值。对获取数据进行统计分析,采用t检验统计学方法进行良性和恶性ADC值比较。联合动态增强扫描和ADC值,采用评分法根据积分情况进行综合定性诊断。比较动态增强扫描、DWI ADC值及联合应用对乳腺病变定性诊断效能。结果：动态增强扫描（病灶边缘、形态学表现结合时间-信号强度曲线）诊断乳腺病变的敏感性、特异性和阳性似然比、阴性似然比分别为89．5％、72．2％和3．221、0．146。良性病变组ADC值1．474±0．441（×100^-3mm^2／s）,恶性病变组ADC值1．082±0．160（×10^-3mm^2／s）,两者间有显著统计学差异（P=0．002,〈0．05）。ADC值诊断敏感性、特异性和阳性似然比、阴性似然比分别为94．7％、66．7％和2．842、0．079。动态增强扫描和DWI-ADC值联合诊断的敏感性、特异性和阳性似然比、阴性似然比分别为94．7％、83．3％和5．684、0．063。结论：磁共振动态增强、扩散加权成像联合应用对乳腺病变的定性诊断敏感性、特异性、阳性似然比、阴性似然比均较单一动态增强扫描或扩散成像诊断效能强。     

Enhanced mass on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

Purpose

To evaluate the diagnostic accuracy of a combination of dynamic contrast‐enhanced MR imaging (DCE‐MRI) and diffusion‐weighted MR imaging (DWI) in characterization of enhanced mass on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

Materials and Methods

We analyzed consecutive breast MR images in 270 patients; however, 13 lesions in 93 patients were excluded based on our criteria. We analyzed tumor size, shape, margin, internal mass enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators of malignancy and calculate a predictive probability for malignancy. We added the corresponding categories to these prediction probabilities for malignancy and calculated diagnostic accuracy when we consider category 4b, 4c, and 5 lesions as malignant and category 4a, 3, and 2 lesions as benign. In a validation study, 75 enhancing lesions in 71 patients were examined consecutively.

Results

Irregular margin, heterogeneous internal enhancement, rim enhancement, plateau time–intensity curve (TIC) pattern, and washout TIC pattern were the strongest indicators of malignancy as well as past studies, and ADC values less than 1.1 × 10^?3 mm²/s were also the strongest indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 92% (56/61), 86% (12/14), 97% (56/58), 71% (12/17), and 91% (68/75), respectively.

Conclusion

The combination of DWI and DCE‐MRI could produce high diagnostic accuracy in the characterization of enhanced mass on breast MR imaging. J. Magn. Reson. Imaging 2008;28:1157–1165. © 2008 Wiley‐Liss, Inc.

     

Non-mass-like enhancement on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

Purpose

To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of lesions showing non-mass-like enhancement on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

Materials and methods

We analyzed consecutive MR images in 45 lesions showing non-mass like enhancement in 41 patients. We analyzed lesion size, distribution, internal enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators for malignancy. In a validation study, 22 non-mass-like enhancement lesions in 21 patients were examined. We calculated diagnostic accuracy when we presume category 4b, 4c, and 5 lesions as malignant or high to moderate suspicion for malignancy, and category 4a and 3 as low suspicion for malignancy or benign.

Results

Segmental distribution (P = 0.018), clumped internal enhancement (P = 0.005), and ADC less than 1.3 × 10⁻³ mm²/s (P = 0.047) were the strongest MR indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 87% (13/15), 86% (6/7), 93% (13/14), 75% (6/8) and 86% (19/22), respectively.

Conclusion

The combination of DCE-MRI and DWI showed high diagnostic accuracy in characterization of non-mass-like enhancement lesions on breast MR images.     

Combined quantitative dynamic contrast-enhanced MR imaging and (1)H MR spectroscopic imaging of human prostate cancer

PURPOSE: To differentiate prostate carcinoma from healthy peripheral zone and central gland using quantitative dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging and two-dimensional (1)H MR spectroscopic imaging (MRSI) combined into one clinical protocol. MATERIALS AND METHODS: Twenty-three prostate cancer patients were studied with a combined DCE-MRI and MRSI protocol. Cancer regions were localized by histopathology of whole mount sections after radical prostatectomy. Pharmacokinetic modeling parameters, K(trans) and k(ep), as well as the relative levels of the prostate metabolites citrate, choline, and creatine, were determined in cancer, healthy peripheral zone (PZ), and in central gland (CG). RESULTS: K(trans) and k(ep) were higher (P < 0.05) in cancer and in CG than in normal PZ. The (choline + creatine)/citrate ratio was elevated in cancer compared to the PZ and CG (P < 0.05). While a (choline + creatine)/citrate ratio above 0.68 was found to be a reliable indicator of cancer, elevated K(trans) was only a reliable cancer indicator in the diagnosis of individual patients. K(trans) and (choline + creatine)/citrate ratios in cancer were poorly correlated (Pearson r(2) = 0.07), and thus microvascular and metabolic abnormalities may have complementary value in cancer diagnosis. CONCLUSION: The combination of high-resolution spatio-vascular information from dynamic MRI and metabolic information from MRSI has excellent potential for improved localization and characterization of prostate cancer in a clinical setting. J. Magn. Reson. Imaging 2004;20:279-287. Copyright 2004 Wiley-Liss, Inc.     

Evolution of pulmonary perfusion defects demonstrated with contrast-enhanced dynamic MR perfusion imaging

Pulmonary perfusion defects can be demonstrated with contrast-enhanced dynamic MR perfusion imaging. We present the case of a patient with a pulmonary artery sarcoma who presented with a post-operative pulmonary embolus and was followed in the post-operative period with dynamic contrast-enhanced MR perfusion imaging. This technique allows rapid imaging of the first passage of contrast material through the lung after bolus injection in a peripheral vein. To our knowledge, this case report is the first to describe the use of this MR technique in showing the evolution of peripheral pulmonary perfusion defects associated with pulmonary emboli. Received: 27 July 1998; Revision received: 28 October 1998; Accepted: 20 January 1999     

Glial neoplasms: dynamic contrast-enhanced T2*-weighted MR imaging.

PURPOSE: To evaluate the role of T2*-weighted echo-planar perfusion imaging by using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood volume (CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy. MATERIALS AND METHODS: MR imaging was performed in 29 patients by using a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV. This information formed the basis for targeting the stereotactic biopsy. Relative CBV values were computed with a nondiffusible tracer model. The relative CBV of lesions was expressed as a percentage of the relative CBV of normal white matter. The maximum relative CBV of each lesion was correlated with the histopathologic grading of astrocytomas obtained from samples from stereotactic biopsy or volumetric resection. RESULTS: The maximum relative CBV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7, with a mean of 5.07 +/- 2.79 (+/- SD), and in the low-grade cohort (n = 3) varied from 0.92 to 2.19, with a mean of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P < .001; Student t test). CONCLUSION: Echo-planar perfusion imaging is useful in the preoperative assessment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invaluable in the precise targeting of the stereotactic biopsy.     

Breast cancer in dense breast: detection with contrast-enhanced dynamic MR imaging

The purpose of this study was to identify contrast enhancement patterns of dense breast parenchyma and to investigate the ability of dynamic magnetic resonance imaging (MRI) to detect cancer in the dense breast. Thirty-two patients with breast cancer in dense breast underwent gadolinium-enhanced dynamic MRI. The detectability of cancer by dynamic MRI, mammography, and physical examination was compared. Two parenchymal enhancement patterns could be identified. One was increasingly multiple patchy enhancement found predominantly in the periphery (type A), and the other was faint enhancement without any nodular opacification (type B). Type A was thought to reflect severe proliferative fibrocystic change (PFC). For both patterns, the detection rate of primary cancers by dynamic MRI was found to be superior to that by other modalities. Dynamic MRI also could detect multifocal cancers, which could not be found with other modalities, although the detectability of these small cancers might be reduced in patients with severe PFC.     

Methods for quantitative assessment of tissue microcirculation using dynamic contrast-enhanced MR imaging

Summary The development of rapid magnetic resonance imaging (MRI) sequences makes it possible to detect the fast kinetics of tissue response after intraveneous administration of paramagnetic contrast media (CM), reflecting the status of tissue microcirculation. In this paper, the basic physical and tracer kinetic principles of dynamic relaxivity and susceptibility contrast MRI techniques are reviewed. The quantitative analysis of the acquired dynamic image data is broken up into an MR specific part, in which the observed signal variations are related to the CM concentration in the tissue, and an MR independent part, in which the computed concentration-time-courses are analyzed by tracer kinetic modeling. The purpose of the applied models is to describe the underlying physiological processes in mathematical terms and thus to enable the estimation of tissue specific parameters from measured dynamic image series. Whereas the capillary permeability can be estimated from dynamic relaxivity contrast enhanced MRI studies, the regional blood volume as well as the regional blood flow can be determined from dynamic susceptibility contrast enhanced image series. However, since there are no intravascular but only diffusible CM available at present, the application of the susceptibility technique is currently restricted to brain tissues with intact blood brain barrier. The practical realization of both dynamic MRI techniques is demonstrated by case studies. Eingegangen am 5. M?rz 1997 Angenommen am 24. April 1997