DCE MRI Research Articles

Comparative Evaluation of Dynamic Contrast-Enhanced Perfusion With Diffusion Tensor Imaging Metrics in Assessment of Corticospinal Tract Infiltration in Malignant Glioma

To compare dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) with diffusion tensor imaging (DTI) for predicting tumor infiltration in a conventional MRI normal-appearing internal capsule adjacent to the tumor in patients with glioblastoma multiforme. Thirty patients with glioblastoma multiforme underwent a neurological examination for motor assessment, DCE MRI, and DTI. On fused DCE and DTI images, regions of interest were placed on the normal-appearing internal capsule and the corresponding region of the contralateral internal capsule. These patients were pooled into group 1 (improved after surgery, n = 9) and group 2 (did not improve after surgery, n = 21) on the basis of motor strength. The DTI and perfusion metrics were statistically analyzed to look for a predictor of motor functionality. Multivariate logistic regression analysis showed only cerebral blood volume to be the predictor of improvement in motor functionality after surgery (P = 0.043). We conclude that cerebral blood volume appears to be the predictor of motor functionality after surgery and may indirectly suggest tumor infiltration, whereas DTI helps to precisely localize the fiber tracts.

Monitoring neovascularization of intraportal islet grafts by dynamic contrast enhanced magnetic resonance imaging

Fifteen thousand youths are diagnosed yearly with type 1 diabetes mellitus. Pancreatic islet transplantation has been shown clinically to provide short-term (~1 year) insulin independence. However, challenges associated with early vascularization of transplanted islet grafts and long-term islet survival remain. We utilized dynamic contrast enhanced magnetic resonance imaging (DCE MRI) to monitor neovascularization of islets transplanted into the right lobe of the liver in a syngeneic mouse model system. The left lobe received no islets and served as a control. DCE data were analyzed for temporal dynamics of contrast (gadolinium) extravasation and the results were fit to a Tofts two-compartment exchange model. We observed maximal right lobe enhancement at seven days post-transplantation. Histological examination up to 28 days was used to confirm imaging results. DCE-derived enhancement strongly correlated with immunohistochemical measures of neovascularization. To our knowledge, these results are the first to demonstrate using a FDA approved contrast agent that DCE MRI can effectively and non-invasively monitor the progression of angiogenesis in intraportal islet grafts.

Correlation of 18F-Fluoromisonidazole Positron Emission and Computed Tomography (18F-FMISO PET/CT) with Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE MRI) in Assessing Tumor Hypoxia in Head and Neck Cancer(HNC) Patients with Nodal Metastases

Hypoxia can develop within the gross tumor corresponding to regions with poor blood perfusion. 18F-FMISO PET/CT images hypoxia while Dynamic Contrast Enhanced MRI (DCE-MRI) detects tumor perfusion. The present study is designed to compare hypoxic and perfusion status of HNC with nodal metastases using 18F-FMISO PET/CT and DCE-MRI imaging.

In vivo imaging demonstrates a time‐line for new vessel formation in islet transplantation

Vascularization of transplanted islets must be maintained to provide long-term graft function. In vivo assessment of new vessel formation in islet grafts has been poorly documented. The purpose of this study was to investigate whether neovascularization was detectable in vivo in a Feridex-labeled murine syngeneic subcapsular islet mass using DCE MRI over 180 days. Subcapsular transplants could be visualized at post-transplant days three, seven, 14, and 28 using T2-weighted MRI and at post-transplant day 180 by immunohistochemistry. Injection of the contrast agent gadolinium (Gd)-DTPA for DCE at three, seven, and 14 days showed increased signal in the transplant area consistent with new vessel formation. Areas under contrast enhancement curves suggested peak angiogenesis at 14 days. At 180 days, there was no observable change in signal intensity after contrast injection suggesting established vascularization or islet mass reduction. Immunohistochemistry confirmed MRI and DCE findings. These data suggest that islet angiogenesis occurs early after transplantation and is likely established after one month of transplantation. This study provides an in vivo time-line of neovascularization in subcapsular islet grafts. We anticipate that contrast extravasation captured by MRI may provide useful monitoring of graft angiogenesis if reproduced in a clinically relevant intraportal model.

IRM et cancer prostatique : mesure de la cinétique du gadolinium avec un système CAD

To assess with a CAD in the peripheral (ZP) and transitional (ZT) zones the areas with modifications of the kinetic parameter Kep (ratio of exchanges between vascular compartment and extravascular extracellular spaces) in prostatic cancers with DCE MRI before radical prostatectomy. Forty-two consecutive patients (mean age 67 years, mean PSA: 8.9 ng/ml) with a prostatic cancer proved after a set of 12 biopsies underwent, before radical prostatectomy, a dynamic MRI (1.5T) with a surface coil after injection of gadolinium. We look with a CAD for foci of voxels with an abnormal Kep in ZP and/or in ZT. Foci of abnormal voxels computerized were compared with histological results of radical prostatectomies: prostates were shared in 12 sectors (six peripheral and six central) and a total of 504 sectors were studied. The links between prostatic capsule and foci of voxels with elevated Kep were systematically evaluated. The location and the local extension of the various cancerous foci were estimated. A comparison with the results of the T2W and T1 DCE MRI sequences without use of the CAD was made. Eighty-eight percent of investigated patients revealed at least a cancerous focus associated with a group of pathological voxels. Hundred and seventy-eight of the 504 investigated prostatic sectors revealed a cancerous lesion after radical prostatectomy (RP) and 116 a focus of voxels with a pathological Kep being linked to 71 isolated lesions, some of them filling several sectors (47 peripheral and 24 transitional). The automatic research with the software of foci of voxels with a parameter Kep more than 2,2 per minute to detect a cancerous lesion had a sensitivity by sector less than the reading without CAD (69% in ZP and 58% in ZT against respectively, 85 and 66% (p<0.01) but seemed more specific: 98% in PZ and 95% in ZT against respectively, 80 and 82% (p<0.01). After RP, 16 cancers were classified Pt2, 10 Pt2R+ and 16 Pt3. The CAD had a better accuracy (74%) than T2W MRI (60%) to look for an extracapsular extension (EPE) or a risk of positive margins: 86% of extraprostatic extension and 60% of positive margins were near a focus of pathological voxels. CAD allowed a computerized qualitative and quantitative study of DCE MRI. It identified and localized with a good specificity the significant foci. A focus of voxels with elevated Kep against the capsule increased significantly the risk of an extraprostatic extension or a positive margin after radical prostatectomy.

Characterization of Tumor Angiogenesis in Rat Brain Using Iron-Based Vessel Size Index MRI in Combination with Gadolinium-Based Dynamic Contrast-Enhanced MRI

This study aimed at combining an iron-based, steady-state, vessel size index magnetic resonance imaging (VSI MRI) approach, and a gadolinium (Gd)-based, dynamic contrast-enhanced MRI approach (DCE MRI) to characterize tumoral microvasculature. Rats bearing an orthotopic glioma (C6, n=14 and RG2, n=6) underwent DCE MRI and combined VSI and DCE MRI 4 h later, at 2.35 T. Gd-DOTA (200 mumol of Gd per kg) and ultrasmall superparamagnetic iron oxide (USPIO) (200 micromol of iron per kg) were used for DCE and VSI MRI, respectively. C6 and RG2 gliomas were equally permeable to Gd-DOTA but presented different blood volume fractions and VSI, in good agreement with histologic data. The presence of USPIO yielded reduced K(trans) values. The K(trans) values obtained with Gd-DOTA in the absence and in the presence of USPIO were well correlated for the C6 glioma but not for the RG2 glioma. It was also observed that, within the time frame of DCE MRI, USPIO remained intravascular in the C6 glioma whereas it extravasated in the RG2 glioma. In conclusion, VSI and DCE MRI can be combined provided that USPIO does not extravasate with the time frame of the DCE MRI experiment. The mechanisms at the origin of USPIO extravasation remain to be elucidated.

Tumor perfusion assessed by dynamic contrast-enhanced MRI correlates to the grading of renal cell carcinoma: Initial results

In this study, we investigated whether assessment of the tumor perfusion by dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) enables to estimate the morphologic grading of renal cell carcinomas. A total of 21 patients with suspected renal cell cancer were examined using a Gadobutrol-enhanced, dynamic saturation-recovery, turbo-fast, low-angle shot sequence. Tumor perfusion and the tissue–blood ratio within the entire tumor and the most highly vascularized part of the tumor were calculated according to the model of Miles. Immediately after examination, patients underwent surgery, and the results from imaging were compared with the morphological analysis of the histologic grading. Fourteen patients had G2 tumors, and seven patients had G3 tumors. Significantly higher perfusion values ( p < 0.05) were obtained in G3 tumors than in G2 tumors when the entire tumor area was considered (1.59 ± 0.44 (ml/g/min) vs. 1.08 ± 0.38 (ml/g/min)) or its most highly vascularized part (2.14 ± 0.89 (ml/g/min) vs. 1.40 ± 0.49 (ml/g/min)). By contrast, the tissue–blood ratios did not differ significantly between the two groups. In conclusion, unlike tissue–blood ratio, surrogate parameters of the tumor perfusion determined by DCE MRI seem to allow an estimation of the grading of renal cell carcinoma. However, further studies with high case numbers and including patients with G1 tumors are required to evaluate the full potential and clinical impact.

MO‐E‐213A‐01: NCI: Quantitative Imaging Initiatives and Public Resources for Standarized Data Analysis

NCI has developed a number of research initiatives to help promote more standardized methods for the measurement of drug or therapy response using quantitative imaging. These initiatives include the following:1. PAR 07 214: (R01) Industry Academic Partnerships.2. PAR 08 225 (U01): Quantitative Imaging Network (QIN)3. RFA 08 225 (U54): Multi Modality Imaging Platforms4. SAIC Contracts: Data collections for RIDER projectThese initiatives involve the development of public resources for sharing image data and results of measurements that includes repeat and longitudinal measurements for phantom and clinical data for a range of imaging modalities (CT, PET CT, DCE MRI, DW MRI and optical imaging). This presentation will describe these resources and how they can be used to support more standardized quantitative imaging methods. In addition a review of recent juried consensus publications for how to use these NCI resources will be addressed. Finally NCI ongoing efforts to support the efforts of different imaging societies such as the RSNA (QIBA), AAPM, SNM and ISMRM will be presented.Learning Objectives1. Understand NCI initiatives for quantitative imaging2. Understand how to use the public resources to promote imaging standards3. Understand the importance of quantitative imaging as a biomarker for therapy related clinical trials.

Correlation of dynamic contrast enhanced magnetic resonance imaging (DCE MRI) with 18f-fluoromisonidazole positron emission and computed tomography (18F-FMISO PET/CT) in assessing tumor hypoxia in a series of head and neck cancer (HNC) patients with nodal metastases

6083 Background: 18F-FMISO PET/CT is a noninvasive hypoxia imaging modality. Hypoxia can develop within the tumor which typically corresponds to regions with poor blood perfusion. DCE-MRI can yield results on tumor perfusion. The present study compares hypoxic and perfusion status of HNC with nodal metastases using DCE-MRI and 18F-FMISO PET/CT imaging. Methods: 13 HNC (7 base of tongue, 5 tonsil, 1 larynx) patients with nodal metastases underwent both DCE-MRI and 18F-FMISO PET/CT scans prior to chemoradiotherapy. MRI was performed on a 1.5 Tesla GE Excite scanner. DCE-MRI studies were acquired using a fast multi-phase spoiled gradient echo sequence. Antecubital vein catheters delivered a bolus of 0.1 mmol/kg Gd-DTPA at 2 cc/s. For 18F-FMISO PET/CT,∼10.0 mCi of 18F-FMISO was administered IV and images were acquired ∼2 hours later. PET images were reconstructed; CT data were used for attenuation correction. Region of interests (ROIs) were manually drawn by a neuroradiologist. Quantitative DCE-MRI analyses were done using the 2-compartment Tofts model. The analyses calculated the pixel Ktrans(distribution rate constant), ve(extravascular-extra-cellular volume fraction), and kep(redistribution rate constant). 18F-FMISO PET/CT images were analyzed and the uptake by the tumor was scored as: no uptake (score 0); moderate-severe uptake (score 1). Semi-quantitative analysis included standardized uptake value (SUV) measurements. Statistical significance was calculated using a 2-sided Student's t-test, with p &lt; 0.05. Results: A total of 17 nodes were analyzed. For the nodes that showed no hypoxia on PET imaging (n = 7), the mean (±SD) values were: 18F-MISO SUV (1.1 ± 03), Ktrans(0.33 ± 0.18), ve(0.53 ± 0.23), and kep(0.66 ± 0.25). For the nodes that showed moderate to severe 18F-MISO uptake (n = 10) the values were: 18F-FMISO SUV (2.8 ± 08), Ktrans(0.24 ± 0.07), ve(0.61 ± 0.13), and kep (0.43 ± 0.17). A significant lower kep for nodes with 18F-MISO uptake (p = 0.042). Conclusions: Preliminary result supports the hypothesis that the hypoxic nodes are poorly perfused nodes (lower kep values) versus nodes with no hypoxia. No significant financial relationships to disclose.

Magnetic resonance imaging of atherosclerotic lesion with new devised animal surface coil

The ability of dynamic contrast enhanced magnetic resonance imaging (DCE MRI) with a new devised animal surface coil was analyzed in identifying atherosclerotic plaques in the rabbit medium-sized iliac artery (IA). Then a comparative analysis of multi-detector computed tomography (MDCT) and DCE MRI was done in discerning morphology and components of 80 atherosclerotic plaques identified by histopathology. It shows that the DCE MRI may be an emerging noninvasive and economic way to characterize atherosclerotic plaques at present. What’s more, a new devised animal surface coil would further improve the signal-to-noise ratio (SNR) and the quality of imaging. However, CT angiography (CTA) may be better than MR angiography( MRA) in detecting vessel stenosis.

DCE MRI as a Biomarker for Delayed Radiation-induced Neurocognitive Dysfunctions

DCE MRI as a Biomarker for Delayed Radiation-induced Neurocognitive Dysfunctions

Automated Weekly Online Replanning for IMRT of Cervix Cancer

Gy/2-2.5 weeks), and mid-RT (at 45-50 Gy/4-5 weeks). The time-signal intensity (SI) curve and the plateau SI were derived for each tumor pixel of each DCE MRI. The poorly perfused tumor subregions were quantified as lower 10th percentiles of SI among the tumor pixels (SI10). Outcome endpoints, local tumor control and disease-free survival, were correlated with perfusion parameters of the pre-RT, early RT, and mid-RT MRI. Median follow was 4.6 (range: 0.2-9.0) years. Results: Patterns of DCE of the tumor pixels changed during treatment, and the change influenced therapy outcome: In the pre-RT MRI, 16 patients with initial high perfusion (SI10 $ 2.1) had excellent outcome (100% local control and 81% disease-free survival).In28(34%)ofthe82patientswithinitiallylow perfusion(SI10\2.1) onpre-RTMR, thepatternchangedto highperfusion in early-RT (at 20-25 Gy). These patients had an improved local control rate of 93%, compared to those with persistently low perfusion in pre-RT and early-RT MRIs (72%, p = 0.014). If low perfusion persisted to the mid-RT phase (at 45-50 Gy), local control rate decreased further to 66% (p = 0.008). Patients with persistently low perfusion had a disease-free survival rate of 44%, compared to 81% in those with high pre-RT perfusion, and 72% in those with low pre-RT and subsequently high perfusion (p = 0.01). In patients with initially high perfusion pre-RT, a subsequent decrease in SI did not negatively impact on outcome. Conclusions: Tumor perfusion pattern varies during treatment, and such changes critically influence treatment outcome. Persistently low perfusion from the pre-RT through mid-RT phase indicates high risk of treatment failure, while better outcome is associatedwithhighinitial,orhighsubsequentperfusionpatterns,evenwithpriorstatusofpoorperfusion.Ourlimiteddatasuggest thatDCEMRIisaneffectiveandnon-invasivemeanstoassessthetemporalchangesoftumorperfusionstatusduringthetreatment, which may play an essential role in tumor reoxygenation and radioresponsiveness.

Effect of bevacizumab (BEV) and irinotecan (CPT-11) on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in glioblastoma (GBM) patients

2026 Background: DCE-MRI can determine vascular permeability using Ktrans, a volume transfer constant of contrast agent between blood plasma and the extravascular extracellular space. We report a phase II trial to determine the correlation between vascular permeability and radiographic response in GBM patients treated with irinotecan and bevacizumab. Methods: Eligibility included 20 patients with recurrent GBM. Both agents were given every 14 days; bevacizumab at 10 mg/kg IV, and irinotecan at 340 mg/m2 for patients on enzyme inducing antiepileptic drugs (EIAED) and 125 mg/m2 for patients not on EIAED. Radiographic responses were assessed every 6 weeks. DCE-MRIs were performed before administration of chemotherapy, one day after treatment and after the first cycle. The primary endpoint was to examine the effect of bevacizumab and irinotecan treatment on vascular permeability as measured by percent change from baseline in Ktrans. Results: All 20 patients were enrolled, with a median age of 49.5 years. Best responses include one patient with complete response, nine with partial response (response rate=50%), nine patients with stable disease, and one with disease progression. A 6-month progression-free survival (PFS) of 65% and a 6-month overall survival (OS) of 85% were observed. Changes in Ktrans value were highly correlated with the percentage decline in tumor volume from baseline to end of cycle one (Spearman's rank correlation = 0.47; p=0.04). Using a two-sided t-test, borderline significant difference in mean Ktrans at 24 hours between responders and non-responders was obtained at six weeks (p=0.05). No DCE MRI measures at either 24 hours or 6 weeks were determined as predictors of PFS and OS. Fifteen patients discontinued therapy due to disease progression and two patients discontinued treatment due to toxicity (wound healing, n=1; pulmonary embolism, n=1). Conclusions: The utilization of DCE-MRI to determine a reduction in vascular permeability following a combination of bevacizumab and irinotecan is feasible and correlates with the degree of tumor volume decrease, but does not predict survival in this small study. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Genentech Genentech Genentech Genentech

Validation of the selected dose of aflibercept (VEGF Trap) plus irinotecan, 5-fluorouracil, and leucovorin (I-LV5FU2) in a phase I clinical trial of patients (pts) with advanced solid tumors (STs): Preliminary results

14540 Background: Aflibercept (AF), a potent angiogenesis inhibitor fusion protein, is comprised of human VEGF receptor VEGFR1 (Flt-1) and VEGFR2 (Flk-1) extracellular domains fused to the Fc portion of human IgG1. A phase I dose escalation study established the AF 4.0 mg/kg + I-LV5FU2 (standard dose) every 2 weeks (q2w) as the recommended dose to be confirmed in a feasibility study. Methods: This was a randomized, double blind feasibility study of AF (4.0 mg/kg) or placebo + I-LV5FU2 at cycle 1, followed in subsequent cy by AF (4.0 mg/kg) + I-LV5FU2 q2w in pts with solid tumors. Study endpoints were to confirm the AF dose, explore the safety, preliminary efficacy and antivascular activity (DCE MRI) of AF. DCE MRI was performed at cycle 1 and 2, all imagings were centrally reviewed. Results: 27 pts were treated in both arms (15 male/12 female), median age 54 [39–75], ECOG PS 0/1/2: 12/11/4, with 70% of colorectal cancers. All pts received prior chemotherapy (CT): median 3 [1–6], 21 pts were previously tre...

Dynamic contrast enhanced MRI (DCE MRI) for Phase I anti-angiogenic trial: Comparison of the transfer constant (Ktrans) to blood flow and permeability derived by a distributed parameter model

3514 Background: The distributed parameter (DP) model is a DCE-MRI model that enables derivation of blood flow and capillary permeability-surface area product (PS). We aim to compare the DP model to Ktrans in the assessment of angiogenesis assessment in a Phase I anti- angiogenic trial. Methods: Twenty-seven evaluable patients from a completed phase I trial (ABT-869) with 3 dose escalations formed the study population. All patients underwent DCE-MRI at baseline, Day 3 and Day 15 with temporal resolution of 4 seconds. Gadolinium concentrations were estimated using dual flip angle method. Ktrans, normalized IAUC60, permeability-surface area product derived from DP model (DP-PS), and blood flow derived from DP model, were calculated. Patients demonstrating progressive disease in first 2 evaluations scans (cycle 2 or 4) based on RECIST criteria were considered progressors and all other patients, non-progressors. Receiver operating curve (ROC) analysis was performed. Correlation with area under the curve extrapolated to infinity (AUCinf) was analyzed. Results: There is good correlation between DP-PS and drug exposure above threshold (threshold concentration 80 ng/mL; time threshold 3.5 hours) measured by AUCinf (Spearman's coefficient −0.556, p = 0.007). Although slightly weaker correlation is found with normalized IAUC60 (Spearman's coefficient −0.537, p = 0.01), the difference is not significant. (p = 0.9334) There is poor correlation for Ktrans (Spearman's coefficient −0.128, p = 0.570). ROC analysis for predicting progressors versus non-progressors showed a higher ROC area for DP-PS compared to Ktrans (0.869 versus 0.417, p < 0.001) and normalized IAUC60 (0.869 versus 0.643, p = 0.1543, not significant). Using a 29.45% drop from baseline at Day 15 to predict non-progressors, the sensitivity of DP-PS is 64.3% and the specificity is 100% whereas the sensitivity of Ktrans is 28.6% and the specificity is 66.7%. In 7 cases, DP-PS correctly predicted the eventual outcome whereas Ktrans predicted the direct opposite. Conclusion: Permeability-surface area product derived from DP model shows better correlation with drug exposure and may predict patient outcome better than Ktrans. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Abbott Laboratories Abbott Laboratories Abbott Laboratories

Comparison of tumor histology to dynamic contrast enhanced magnetic resonance imaging-based physiological estimates

The purpose of this study was to compare histologically determined cellularity and extracellular space to dynamic contrast-enhanced magnetic resonance imaging (DCE MRI)-based maps of a two-compartment model's parameters describing tumor contrast agent extravasation, specifically tumor extravascular extracellular space (EES) volume fraction (ve), tumor plasma volume fraction (vp) and volume-normalized contrast agent transfer rate between tumor plasma and interstitium (KTRANS/VT). Obtained ve, vp and KTRANS/VT maps were estimated from gadolinium diethylenetriamine penta-acetic acid DCE T1-weighted gradient-echo images at resolutions of 469, 938 and 2500 microm. These parameter maps were compared at each resolution to histologically determined tumor type, and the high-resolution 469-microm maps were compared with automated cell counting using Otsu's method and a color-thresholding method for estimated intracellular (Vintracellular) and extracellular (Vextracellular) space fractions. The top five KTRANS/VT values obtained from each tumor at 469 and 938 microm resolutions are significantly different from those obtained at 2500 microm (P<.0001) and from one another (P=.0014). Using these top five KTRANS/VT values and the corresponding tumor EES volume fractions ve, we can statistically differentiate invasive ductal carcinomas from noninvasive papillary carcinomas for the 469- and 938-microm resolutions (P=.0017 and P=.0047, respectively), but not for the 2500-microm resolution (P=.9008). The color-thresholding method demonstrated that ve measured by DCE MRI is statistically similar to histologically determined EES. The Vextracellular obtained from the color-thresholding method was statistically similar to the ve measured with DCE MRI for the top 10 KTRANS/VT values (P>.05). DCE MRI-based KTRANS/VT estimates are not statistically correlated with histologically determined cellularity. DCE MRI estimates of tumor physiology are a limited representation of tumor histological features. Extracellular spaces measured by both DCE MRI and microscopic analysis are statistically similar. Tumor typing by DCE MRI is spatial resolution dependent, as lower resolutions average out contributions to voxel-based estimates of KTRANS/VT. Thus, an appropriate resolution window is essential for DCE MRI tumor diagnosis. Within this resolution window, the top KTRANS/VT values with corresponding ve are diagnostic for the tumor types analyzed in this study.

Differences in perfusion parameters between upper and lower lumbar vertebral segments with dynamic contrast-enhanced MRI (DCE MRI)

To investigate the influence of age, sex and spinal level on perfusion parameters of normal lumbar bone marrow with dynamic contrast-enhanced MRI (DCE MRI). Sixty-seven subjects referred for evaluation of low back pain or sciatica underwent DCE MRI of the lumbar spine. After subtraction of dynamic images, a region of interest (ROI) was placed on each lumbar vertebral body of all subjects, and time intensity curves were generated. Consequently, perfusion parameters were calculated. Statistical analysis was performed to search for perfusion differences among lumbar vertebrae and in relation to age and sex. Upper (L1, L2) and lower (L3, L4, L5) vertebrae showed significant differences in perfusion parameters (p<0.05). Vertebrae of subjects younger than 50 years showed significantly higher perfusion compared to vertebrae of older ones (p<0.05). Vertebrae of females demonstrated significantly increased perfusion compared to those of males of corresponding age (p<0.05). All perfusion parameters, except for washout (WOUT), showed a mild linear correlation with age. Time to maximum slope (TMSP) and time to peak (TTPK) showed the same correlation with sex (0.22<r<0.32, p<0.05). Our results indicate increased perfusion of the upper compared to the lower lumbar spine, of younger compared to older subjects and of females compared to males.

Comparative study of diffusion weighted imaging and dynamic contrast enhanced MRI for the detection of small breast cancers

Objecfive To compare the sensitivity of diffusion weighted imaging(DWI)with dynamic contrast enhanced(DeE)MRI for the detection of small breast caJlcers and to evaluate the clinical value of DWI.Methods Forty-eight patients with benign(n=25)and malignant(n=45)small breast lesions(≤2 cm)proved by pathology underwent DWI and DCE MRI.The DCE MRI was performed using FLASH sequence and the time-signal intensity chive was drawn.The DWl was performed using GRAPPAEPI sequence with different b values(800,1000 s/mm2) and the ADC values of lesions were measured.The sensitivity and specificity of DWI for the detection of small breast cancers were compared with DCE MRI. Results Forty of 45 small breast cancers and 19 of 25 small benign breast lesions were corrlectly diagnosed using DCE MRI.The sensitivity and positive predictive value of TIC were 88.9%(40/45)and 87.0%(40/46).With b values of 800 s/mm2 and 1000 s/mm2,the avemge ADC values of small breast cancers were(1.153±0.192)× 10-3 and(1.079±0.186)× 10-3 mm2/s,while those of benign ones were (1.473±0.252)×10-3 and(1.419±0.255)×10-3 mm2/s,respeetively. There was no significant difference for the ADC values with different b values in the same group(P＞0.05),while there was a signiticant difference between the malignant and the benign lesions(P＜0.05)Thirty-nine of 45 small breast cancers and 19 of 25 small benign breast lesions were correctly diagnosed using DWI with b value of 1000see/mm2.Both the sensitivity and positive predictive value of diagnosis were 86.7%(39/45).The abilities of DWI and DCE MRI for the diagnosis of small breast cancers werle the same. The sensitivity(93.3%)and positive predictive value(91.3%)were improved with the combination of DCE MRI and DWI. Conclusion DWI has a high sensitivity for the detection of small breast cancers,the ADC value can provide valuable information in the differential diagnosis. Key words: Breast neoplasm; Magnetic resonance imaging; Diffusion; Image enhancement

Dynamic contrast-enhanced MRI of benign prostatic hyperplasia and prostatic carcinoma: correlation with angiogenesis

To investigate the diagnostic and differential diagnostic values of dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) in prostatic diseases, and to investigate the correlation between the parameters of SI-T curves and angiogenesis. Twenty-one patients with proven prostatic carcinoma (Pca) and 29 patients with proven benign prostatic hyperplasia (BPH) were examined using DCE MRI. Diagnostic characteristics for differentiation were examined using threshold values for maximum peak time, enhancement degree, and enhancement rate. Then, the signal intensity-time curves (SI-T curves) were analysed, and the correlations between the parameters of SI-T curves and the expression levels of vascular endothelial growth factor (VEGF) and microvascular density (MVD) were investigated. All patents underwent prostatectomy. DCE MRI and histological findings were correlated. Pca showed stronger enhancement with an earlier peak time, higher enhancement, and enhancement rate (p<0.05). Regarding the type of SI-T curves, in the BPH group six were type A, 10 were type B, and 13 were type C, whereas in the Pca group, 14 were type A, six were type B, and only one was type C (Chi-square test, chi2=13.57, P<0.005). The VEGF and MVD expression levels of Pca were higher than those of BPH. Peak time was negatively correlated with the expression levels of VEGF and MVD, whereas the enhancement degree and enhancement rate showed positive correlations (Pearson correlation, p<0.05). Based on T2-weighted imaging, DCE MRI curves can help to differentiate benign from malignant prostate tissue. In the present study the type C curve was rarely seen with malignant disease, but these results need confirmation.

Simultaneous dynamic T 1 and T 2 * measurement for AIF assessment combined with DCE MRI in a mouse tumor model

A double-delay SR-MGE-SNAP sequence allowing simultaneous T1 and T2* measurement was developed for integrating arterial input function (AIF) measurement into DCE MRI. Implemented on a 4.7-T animal MR system, this technique was applied to mice with colorectal tumor xenografts. AIF, measured in the mouse heart, was modeled by a bi-exponential function, whereas tumor K(trans) and v(e) parameter maps were obtained from analysis with a two- compartment model using an individually measured AIF. AIF analysis of T2*-corrected data yielded A1 = 9.2 +/- 4.3 kg/l, A(2) = 4.2 +/- 0.8 kg/l, m1 = 2.3 +/- 1.1 min(-1), and m2 = 0.05 +/- 0.02 min(-1). The mean initial plasma concentration C ( p )(t = 0) = 8.0 +/- 2.7 mM was compatible with estimated 8.6 mM. Without T2*-correction distribution phase parameters A1, m1, and C(p)(t = 0) were underestimated. In tumors, neglect of T2* effects yielded mean K(trans) values which were reduced by 14% (P < 0.05), whereas v(e) showed only a slight non-significant reduction. Simultaneous measurement of DeltaR1 and DeltaR2* studied in highly and poorly vascularized and (pre-)necrotic tumor regions revealed complementary behavior of both parameters with respect to vascular properties. In conclusion, the presented measurement technique is a promising tool for dynamic MRI applications studied in animal models at high field strengths and/or with CA of high relaxivities, as it combines classical DCE MRI integrating AIF assessment with dynamic T2* measurement.