Can high-spatial resolution T2-weighted endorectal MRI rule out clinically significant prostate cancer?

PURPOSE: To evaluate whether clinically significant prostate cancer (PCa) can be ruled out by high-spatial resolution T2-weighted endorectal MRI (eMRI) in a cohort of patients with biopsy-proven PCa. PATIENTS AND METHODS: A retrospective analysis was carried out for consecutive patients who underwent 1.5 Tesla eMRI for local staging before open radical prostatectomy. The cohort was dichotomized into patients with apparent or inapparent tumour on eMRI. The results were compared with final histopathology, and an analysis for presence of clinically significance PCa was performed. RESULTS: A total of 385 patients were included in the study; in 85 patients (22 %), no apparent lesion suspicious for PCa was detected on eMRI, still final pathology revealed clinically significant PCa in 61 of these patients (72 %). In contrast, 256 (85 %) of the 300 patients with apparent tumour in eMRI harboured clinically significant PCa. eMRI could not differentiate clinically significant from insignificant PCa in neither of the groups (p > 0.6). CONCLUSIONS: Presence of clinically significant cancer cannot be excluded by high-resolution 1.5 Tesla T2-weighted eMRI. The results of the study suggest that the role of T2-weighted eMRI for selecting patients suitable for AS is limited.

Accuracy of preoperative endorectal MRI in predicting extracapsular extension and influence on neurovascular bundle sparing in radical prostatectomy.

PURPOSE: To evaluate the accuracy of presurgical endorectal MRI (eMRI) for local staging before radical prostatectomy (RP) and its influence on neurovascular bundle (NVB) resection during radical prostatectomy. PATIENTS AND METHODS: A total of 385 patients with histologically proven prostate cancer (PCa) have been included in this retrospective study between 2004 and 2008. All patients underwent preoperative eMRI at 1.5 T before open RP. Staging results by eMRI were compared with the histopathological findings. The presence of positive surgical margins and extent of nerve-sparing procedure were evaluated. Subgroup analysis of low-risk group and intermediate to high-risk group based on D'Amico criteria was conducted. RESULTS: In 294 (76.4%) patients, pathological stage was correctly predicted, 69 patients (17.9%) were understaged and 22 (5.7%) overstaged. Overall sensitivity, specificity, negative and positive predictive value for predicting extracapsular extension (ECE) were 41.5, 91.8, 78.0 and 69.0%, respectively. One hundred and fifty-two (48.4%) of the patients classified as stage cT2 by eMRI underwent bilateral NVB sparing, whereas 14 (19.7%) patients with reported ECE underwent bilateral NVB sparing (P < 0.01). Overall positive surgical margin rate was 14.8%. Sensitivity of predicting ECE and positive predictive value were lower in the low-risk group than in the intermediate and high-risk group. CONCLUSIONS: eMRI is effective in predicting extracapsular extension in an intermediate to high-risk group. Preoperative eMRI in patients with low-risk criteria is not recommended as a routine assessment modality. eMRI findings did appear to influence surgical strategy as patients with imaging findings suggesting >cT2 disease were less likely to undergo NVB sparing.

Technical performance evaluation of a human brain PET/MRI system.

OBJECTIVES: Technical performance evaluation of a human brain PET/MRI system. METHODS: The magnetic field compatible positron emission tomography (PET) insert is based on avalanche photodiode (APD) arrays coupled with lutetium oxyorthosilicate (LSO) crystals and slip-fits into a slightly modified clinical 3-T MRI system. The mutual interference between the two imaging techniques was minimised by the careful design of the hardware to maintain the quality of the B (0) and B (1) field homogeneity. RESULTS: The signal-to-noise ratio (SNR) and the homogeneity of the MR images were minimally influenced by the presence of the PET. Measurements according to the Function Biomedical Informatics Research Network (FBIRN) protocol proved the combined system's ability to perform functional MRI (fMRI). The performance of the PET insert was evaluated according to the National Electrical Manufacturers Association (NEMA) standard. The noise equivalent count rate (NEC) peaked at 30.7 × 10(3) counts/s at 7.3 kBq/mL. The point source sensitivity was greater than 7 %. The spatial resolution in the centre field of view was less than 3 mm. Patient data sets clearly revealed a noticeably good PET and MR image quality. CONCLUSION: PET and MRI phantom tests and first patient data exhibit the device's potential for simultaneous multiparametric imaging. KEY POINTS: • Combination of PET and MRI is a new emerging imaging technology. • Evaluated brain PET/MRI enables uncompromised imaging performance. • PET/MRI aims to provide multiparametric imaging allowing acquisition of morphology and metabolism.

Multiphase contrast-enhanced CT with highly concentrated contrast agent can be used for PET attenuation correction in integrated PET/CT imaging.

PURPOSE: State-of-the-art positron emission tomography/computed tomography (PET/CT) systems incorporate multislice CT technology, thus facilitating the acquisition of multiphase, contrast-enhanced CT data as part of integrated PET/CT imaging protocols. We assess the influence of a highly concentrated iodinated contrast medium (CM) on quantification and image quality following CT-based attenuation correction (CT-AC) in PET/CT. METHODS: Twenty-eight patients with suspected malignant liver lesions were enrolled prospectively. PET/CT was performed 60 min after injection of 400 MBq of (18)F-fluorodeoxyglucose (FDG) and following the biphasic administration of an intravenous CM (400 mg iodine/ml, Iomeron 400). PET images were reconstructed with CT-AC using any of four acquired CT image sets: non-enhanced, pre-contrast (n-PET), arterial phase (art-PET), portal venous phase (pv-PET) and late phase (late-PET). Normal tissue activity and liver lesions were assessed visually and quantitatively on each PET/CT image set. RESULTS: Visual assessment of PET following CT-AC revealed no noticeable difference in image appearance or quality when using any of the four CT data sets for CT-AC. A total of 44 PET-positive liver lesions was identified in 21 of 28 patients. There were no false-negative or false-positive lesions on PET. Mean standardized uptake values (SUV) in 36 evaluable lesions were: 5.5 (n-PET), 5.8 (art-PET), 5.8 (pv-PET) and 5.8 (late-PET), with the highest mean increase in mean SUV of 6%. Mean SUV changes in liver background increased by up to 10% from n-PET to pv-PET. CONCLUSION: Multiphase CT data acquired with the use of highly concentrated CM can be used for qualitative assessment of liver lesions in torso FDG PET/CT. The influence on quantification of FDG uptake is small and negligible for most clinical applications.

Whole-body diffusion-weighted MRI with apparent diffusion coefficient mapping for early response monitoring in multiple myeloma: preliminary results.

OBJECTIVE: The purpose of our study was to prospectively assess the feasibility of whole-body diffusion-weighted imaging (DWI) for short-term evaluation of response to treatment in multiple myeloma patients using a single-shot echo-planar imaging DWI sequence with a Stejskal-Tanner diffusion encoding scheme and spectral fat suppression. SUBJECTS AND METHODS: Twelve consecutive patients (nine men and three women; mean age, 61.4 years; age range, 54-79 years) underwent whole-body DWI (b = 50, 400, and 800 s/mm(2)) both at baseline and 3 weeks (mean, 23 days) after onset of therapy. Bone marrow and extramedullary manifestations were evaluated by quantitative image analysis using measurements of the mean apparent diffusion coefficient (ADC). These parameters were correlated with myeloma response according to standard criteria and were evaluated parallel to MRI and continuously for more than 6 months afterward. RESULTS: Fifty-three myeloma lesions, 50 medullary (28 axial and 22 appendicular skeleton) and three extramedullary, were analyzed. Eleven patients were classified as responders and one as a nonresponder. DWI results accurately (100%) correlated with disease course according to standard clinical and laboratory criteria. All involved lesions showed restricted diffusion at baseline. ADC quantification yielded an increase of 63.9% (range, 8.7-211.3%) in responders and a decrease of 7.8% in the sole nonresponding patient during therapy. In parallel, M-gradient measurement showed a mean decrease of 45.1% (range, 19.6-88.8%) in responders and an increase of 21.8% in the nonresponder. Amplitude of response measured by the course of ADC values proved higher in the appendicular skeleton (99.8%) compared with the axial skeleton (54.3%) (p = 0.037). CONCLUSION: Whole-body DWI with ADC analysis represents a feasible diagnostic tool for assessment of short-term treatment response in myeloma patients.

Tumorsize dependent detection rate of endorectal MRI of prostate cancer--a histopathologic correlation with whole-mount sections in 70 patients with prostate cancer.

PURPOSE: To evaluate the value of T2w endorectal MRI (eMRI) for correct detection of tumor foci within the prostate regarding tumor size. MATERIALS AND METHODS: 70 patients with histologically proven prostate cancer were examined with T2w eMRI before radical prostatectomy at a 1.5T scanner. For evaluation of eMRI, two radiologists evaluated each tumor focus within the gland. After radical prostatectomy, the prostates were prepared as whole-mount sections, according to transversal T2w eMRI. For each slice, tumor surroundings were marked and compared with eMRI. Based on whole-mount section, 315 slices were evaluated and 533 tumor lesions were documented. RESULTS: Based on the T2w eMRI, 213 tumor lesions were described. In 137/213, histology could prove these lesions. EMRI was able to visualize 0/56 lesions with a maximum size of <0.3 cm (detection rate 0%), between 0.3 and 0.5 cm 4/116 (3%), between 1 and 0.5 cm 22/169 (13%), between 2 and 1cm 61/136 (45%) and for >2 cm 50/56 (89%). False positive eMRI findings were: <0.3 cm n=0, 0.5-0.3 cm n=12, 0.5-1cm n=34, 1-2 cm n=28 and >2 cm n=2. CONCLUSION: T2w eMRI cannot exclude prostate cancer with lesions smaller 10mm and 0.4 cm(3) respectively. The detection rate for lesions more than 20mm (1.6 cm(3)) is to be considered as high.

Topographical sensitivity and specificity of endorectal coil magnetic resonance imaging for prostate cancer detection.

OBJECTIVES: Endorectal coil magnetic resonance imaging (EC-MRI) is useful to evaluate prostate cancer localization. Herein, we evaluate sensitivity and specificity of EC-MRI in different regions of the prostate by comparing the acquired images to whole-mount sections of the prostate after radical prostatectomy. METHODS: 69 patients with localized prostate cancer were included. After virtually dividing the prostate into 12 sectors, results of EC-MRI were compared to corresponding whole-mount sections by contingency analysis. Sensitivity and specificity were calculated for each of the 12 areas as well as for the dorsal and ventral region. RESULTS: Sensitivity right/left was dorsal apex/mid/base 41/41, 60/67 and 73/79%; ventral 33/52, 43/42 and 47/52%. Specificity right/left was dorsal apex/mid/base 92/89, 82/75 and 88/69%; ventral 100/100, 100/92 and 88/83%. Local sensitivity and specificity regarding dorsal versus ventral was 88/100 and 65/87%. CONCLUSIONS: Local sensitivity decreased from basodorsal to apicoventral direction, whereas local specificity increased in the same direction. Therefore, prostate cancers demonstrated by MRI are more prone to be detected in the basodorsal region, whereas less false-positive results are found in the apicoventral region. These variations in topographical specificity and sensitivity need to be considered before radical prostatectomy or MRI-guided biopsy.

Simultaneous PET-MRI: a new approach for functional and morphological imaging.

Noninvasive imaging at the molecular level is an emerging field in biomedical research. This paper introduces a new technology synergizing two leading imaging methodologies: positron emission tomography (PET) and magnetic resonance imaging (MRI). Although the value of PET lies in its high-sensitivity tracking of biomarkers in vivo, it lacks resolving morphology. MRI has lower sensitivity, but produces high soft-tissue contrast and provides spectroscopic information and functional MRI (fMRI). We have developed a three-dimensional animal PET scanner that is built into a 7-T MRI. Our evaluations show that both modalities preserve their functionality, even when operated isochronously. With this combined imaging system, we simultaneously acquired functional and morphological PET-MRI data from living mice. PET-MRI provides a powerful tool for studying biology and pathology in preclinical research and has great potential for clinical applications. Combining fMRI and spectroscopy with PET paves the way for a new perspective in molecular imaging.

Tumor detection by diffusion-weighted MRI and ADC-mapping--initial clinical experiences in comparison to PET-CT.

OBJECTIVE: To evaluate the clinical potential of diffusion-weighted-imaging (DWI) with apparent diffusion coefficient (ADC)-mapping for tumor detection. MATERIALS AND METHODS: A single-shot echo-planar-imaging DWI sequence with fat suppression and ability for navigator-based respiratory triggering was implemented. Nineteen patients (11 melanoma, 4 prostate cancer, 1 non-Hodgkin lymphoma, and 3 lung cancer) were examined by positron emission tomography (PET) with an integrated computed tomography scanner (PET-CT) and DWI. Images at b = 0, 400, and 1000 s/mm2 were acquired and ADC maps were generated. PET examinations were used as a reference for tumor detection. Four hundred twenty-four regions of interest were used for DWI and 73 for PET data evaluation. RESULTS: DWI and ADC maps were of diagnostic quality. Metastases with increased tracer uptake were clearly visualized at b = 1000 s/mm2 with the exception of mediastinal lymph node metastases in cases of lung cancer. ADC mapping did not improve detection rates. CONCLUSIONS: DWI is a feasible clinical technique, improving the assessment of metastatic spread in routine magnetic resonance imaging examinations.

Morphologic, functional, and metabolic magnetic resonance imaging-guided prostate biopsy in a patient with prior negative transrectal ultrasound-guided biopsies and persistently elevated prostate-specific antigen levels.

A 65-year-old patient was examined with [11C]-choline positron emission tomography-computed tomography and magnetic resonance imaging (MRI) for possible tumor detection after two negative sessions of transrectal ultrasound-guided prostate biopsy and persistently elevated prostate-specific antigen levels for 27 months. Choline positron emission tomography revealed a small and circumscribed pathologic tracer uptake in the right dorsal peripheral gland. Whereas T2-weighted MRI and high b-value diffusion-weighted imaging were able to reproduce this suspicious area, proton MR spectroscopy showed no significant increase of the amplitude of choline-containing compounds. Magnetic resonance imaging-guided prostate biopsy was successfully performed. All specimens taken from the lesion showed a Gleason 5 tubular adenocarcinoma with low proliferative activity.

Highly resolved free-breathing magnetic resonance cholangiopancreatography in the diagnostic workup of pancreaticobiliary diseases in infants and young children--initial experiences.

PURPOSE: A new generation of magnetic resonance imaging scanner offers a 3-dimensional magnetic resonance cholangiopancreatography (MRCP) with very high spatial resolution using a non-breath-hold technique with prospective navigator gating. The study aimed to investigate the new technology of the MRCP in infants with suspected pancreaticobiliary diseases. METHODS: Seven patients (4 girls, 3 boys; mean age, 2.8 years; range, 3 months to 5.6 years) were examined. All patients underwent magnetic resonance imaging examination using a 1.5-T whole-body scanner (Magnetom Avanto, Siemens Medical, Erlangen, Germany). For MRCP, a heavily T2-weighted (time to echo, 678 ms) 3-dimensional turbo spin echo in coronal plane was performed with the voxel size of 1 x 1 x 1.5 mm. To enable non-breath-holding imaging, a diaphragm navigator sequence was simultaneously carried out. The MRCP findings were compared prospectively with the endoscopic retrograde cholangiopancreatography and/or with the surgical findings in 6 of 7 cases. In 1 patient, the follow-up was considered reference standard. RESULTS: The high spatial resolution of the images without breathing artifacts allowed an excellent demonstration of all relevant pancreaticobiliary ducts and of the pathologic findings. All patients (n = 4) with choledocholithiasis were identified through MRCP. The finding of a high pancreaticobiliary junction (n = 3) was confirmed by endoscopic retrograde cholangiopancreatography in all cases. The length of the common channel ranged from 16 to 24 mm. In 1 patient, the long common channel was associated with a choledochal cyst. In a 1.7-year-old boy with recurrent abdominal pain and mild pancreatitis, the rare case of a gastric duplication with connection to the main pancreatic duct was diagnosed. A regular gastric wall with normal mucosa and parts of the duodenal wall with a circular layer of muscle (pylorus-like) were found in histology after surgical resection of the mass. CONCLUSION: The newly developed technique may be a reliable tool in the workup of pancreaticobiliary diseases in infants.

Diagnostic value of MRI in a pelvic mass of prostatic origin.

We report on the case of a 55-year-old male with acute urinary retention, caused by a large pelvic mass. Contrast enhanced computed tomography showed a vascularized prostatic mass with calcifications. To rule out potential bladder and rectum infiltration and to optimize imaging prior to surgical exploration, an MRI examination including MR angiography and spectroscopy was performed. Clinical findings including intraoperative results are presented in this report in detail and correlated to the results of the state of the art magnetic resonance imaging.

MRI-guided biopsy of the prostate increases diagnostic performance in men with elevated or increasing PSA levels after previous negative TRUS biopsies.

OBJECTIVES: Repeatedly negative prostate biopsies in individuals with elevated prostate specific antigen (PSA) levels can be frustrating for both the patient and the urologist. This study was performed to investigate if magnetic resonance imaging (MRI)-guided transrectal biopsy increases diagnostic performance in individuals with elevated or increasing PSA levels after previous negative conventional transrectal ultrasound (TRUS)-guided biopsies. METHODS: 27 consecutive men with a PSA >4 ng/ml and/or suspicious finding on digital rectal examination, suspicious MRI findings, and at least one prior negative prostate biopsy were included. Median age was 66 years (mean, 64.5+/-6.8); median PSA was 10.2 ng/ml (mean, 11.3+/-5.5). MRI-guided biopsy was performed with a closed unit at 1.5 Tesla, an MRI-compatible biopsy device, a needle guide, and a titanium double-shoot biopsy gun. RESULTS: Median prostate volume was 37.4 cm3 (mean, 48.4+/-31.5); median volume of tumor suspicious areas on T2w MR images was 0.83 cm3 (mean, 0.99+/-0.78). The mean number of obtained cores per patient was 5.22+/-1.45 (median, 5; range, 2-8). Prostate cancer was detected in 55.5% (15 of 27) of the men. MRI-guided biopsy could be performed without complications in all cases. CONCLUSION: According to our knowledge, this is the largest cohort of consecutive men to be examined by MRI-guided transrectal biopsy of the prostate in this setting. The method is safe, can be useful to select suspicious areas in the prostate, and has the potential to improve cancer detection rate in men with previous negative TRUS-biopsies.

Magnetic resonance imaging of the body trunk using a single-slab, 3-dimensional, T2-weighted turbo-spin-echo sequence with high sampling efficiency (SPACE) for high spatial resolution imaging: initial clinical experiences.

PURPOSE: The authors conducted a clinical evaluation of single-slab, 3-dimensional, T2-weighted turbo-spin-echo (TSE) with high sampling efficiency (SPACE) for high isotropic body imaging with large field-of-view (FoV). MATERIALS AND METHODS: Fifty patients were examined in clinical routine with SPACE (regions of interest: pelvis n=30, lower spine n=12, upper spine n=6, extremities n=4) at 1.5 T. For achieving a high sampling efficiency, parallel imaging, high turbofactor, and magnetization restore pulses were used. In contrast to a conventional TSE imaging technique with constant flip angle refocusing, the refocusing pulse train of the SPACE sequence consists of variable flip angle radiofrequency pulses along the echo train. RESULTS: Signal-to-noise ratio and contrast-to-noise ratio of SPACE images were of sufficient diagnostic value. The possibility of image reconstruction in multiple planes was of clinical relevance in all cases and simplified data analysis. CONCLUSION: The achievement of 3-dimensional, T2-weighted TSE magnetic resonance imaging with isotropic and high spatial resolution and interactive 3-dimensional visualization essentially improve the diagnostic potential of magnetic resonance imaging.

Potential applications of flat-panel volumetric CT in morphologic and functional small animal imaging.

Noninvasive radiologic imaging has recently gained considerable interest in basic and preclinical research for monitoring disease progression and therapeutic efficacy. In this report, we introduce flat-panel volumetric computed tomography (fpVCT) as a powerful new tool for noninvasive imaging of different organ systems in preclinical research. The three-dimensional visualization that is achieved by isotropic high-resolution datasets is illustrated for the skeleton, chest, abdominal organs, and brain of mice. The high image quality of chest scans enables the visualization of small lung nodules in an orthotopic lung cancer model and the reliable imaging of therapy side effects such as lung fibrosis. Using contrast-enhanced scans, fpVCT displayed the vascular trees of the brain, liver, and kidney down to the subsegmental level. Functional application of fpVCT in dynamic contrast-enhanced scans of the rat brain delivered physiologically reliable data of perfusion and tissue blood volume. Beyond scanning of small animal models as demonstrated here, fpVCT provides the ability to image animals up to the size of primates.

Follow-up gliomas after radiotherapy: 1H MR spectroscopic imaging for increasing diagnostic accuracy.

We evaluated the value of magnetic resonance imaging (MRI) and the additional benefit of proton MR spectroscopic imaging (1H SI) in patients with a new suspicious lesion after fractionated stereotactic radiotherapy (FSRT) of a glioma. Thirty-four patients with histologically proven astrocytoma WHO II-IV after treatment by FSRT and a new suspect lesion in the follow-up were included in this study. Data were analysed by three independent radiologists with different experience in 1H SI: Data were verified by clinical follow-up (PT, progressive tumour; nPT, non-progressive tumour) and a kappa analysis was performed. Sensitivity and specificity of T1 weighted (w) and T2w MRI was compared (imaging at radiotherapy and follow-up) using further follow-up controls as gold standard and the additional benefit of 1H SI (imaging at follow-up) was calculated. Mean interval between last irradiation and detection of a suspicious lesion was 37 +/- 32 months. Time to clinical evaluation was 13 +/- 8 months. Interobserver agreement was significantly high in all analyses (kappa always >0.8, P < 0.05). T2w imaging proved to be superior to contrast enhanced T1w imaging in sensitivity (87.5 vs 81.25%) and specificity (85.7 vs 57.1%). Solitary 1H SI had similar results as T2w (sensitivity 87.5%, specificity 71.4%). Taking all techniques into account, all PT were correctly diagnosed. Radiologists' experience had no significant influence on correct interpretation of a suspicious lesion. We conclude that 1H SI is helpful in characterising new suspicious lesions in irradiated gliomas, particularly if pre-MRI is not available for evaluating follow-up.

3D proton MR spectroscopic imaging of prostate cancer using a standard spine coil at 1.5 T in clinical routine: a feasibility study.

The objective of this study was to demonstrate the feasibility of 3D proton MR spectroscopic imaging (MRSI) of the prostate using a standard spine instead of a dedicated endorectal coil at 1.5 T. Twenty-eight patients (25 with biopsy proven prostate cancers and three patients with a benign prostate hyperplasia) were examined. MRI and MRSI were conducted with commercial array surface coils at 1.5 T. Ratios of choline (Cho), creatine (Cr) and citrate (Ci) were calculated for tumour, central and peripheral zone retrospectively, based on axial T2 weighed MR images and histology reports. Prostate cancer was characterized by significantly elevated (Cho+Cr)/Ci ratio compared with non-tumourous prostate tissue. The quality of all proton MR spectra was considered to be good or acceptable in 17/28 patients (61%) and poor in 11/28 (39%) examinations. In 20/25 patients with proven malignancy (80%), MRSI was considered to be helpful for the detection of prostate cancer. In 4/25 patients with proven malignancy (16%) who underwent seed implantation, radiotherapy or hormone deprivation before MR examination spectroscopy was of poor and non-diagnostic quality. MRSI of the prostate is feasible within clinical routine using the spine array surface coil at 1.5 T. It can consequently be applied to patients even with contraindications for endorectal coils. However, spectral quality and signal-to-noise ratio is clearly inferior to 3D MRSI examinations with endorectal coils.

Volumetric computed tomography (VCT): a new technology for noninvasive, high-resolution monitoring of tumor angiogenesis.

Volumetric computed tomography (VCT) is a technology in which area detectors are used for imaging large volumes of a subject with isotropic imaging resolution. We are experimenting with a prototype VCT scanner that uses flat-panel X-ray detectors and is designed for high-resolution three-dimensional (3D) imaging. Using this technique, we have demonstrated microangiography of xeno-transplanted skin squamous cell carcinomas in nude mice. VCT shows the vessel architecture of tumors and animals with greater detail and plasticity than has previously been achieved, and is superior to contrast-enhanced magnetic resonance (MR) angiography. VCT and MR images correlate well for larger tumor vessels, which are tracked from their origin on 3D reconstructions of VCT images. When compared with histology, small tumor vessels with a diameter as small as 50 microm were clearly visualized. Furthermore, imaging small vessel networks inside the tumor tissue improved discrimination of vital and necrotic regions. Thus, VCT substantially improves imaging of vascularization in tumors and offers a promising tool for preclinical studies of tumor angiogenesis and antiangiogenic therapies.

Simple models improve the discrimination of prostate cancers from the peripheral gland by T1-weighted dynamic MRI.

Evaluation of the accuracy of descriptive and physiological parameters calculated from signal intensity-time curves using T1-weighted dynamic contrast enhanced MRI (DCE MRI) to differentiate prostate cancers from the peripheral gland. Twenty-seven patients with prostate cancers were examined with DCE MRI prior radical prostatectomy. Regions of interest were defined in tumors and non-affected areas in the peripheral zone. Dynamic data were parameterized in amplitude and exchange rate constant (kep) using a two-compartment model. Additionally, relative slope during 26, 39, 52 and 65 s, areas under the curve (AUC) and time to start of signal intensity increase (tlag) were determined. Vessel density (VD) of excised prostates was quantified in tumor areas using a CD34 stain. The parameter slope52 showed 20% higher values (P<0.001) in tumors than in the peripheral gland and compared with the other parameters the largest area under the ROC curve (0.81). The minimum total error rate was attained at a cut-point of 0.021, yielding a sample value of sensitivity and specificity of 70% and 88%, respectively, and a bias-corrected sum of sensitivity and specificity of 1.54. In addition, amplitude (P<0.001), kep (P=0.03) and AUC (P<0.001) were significantly higher in tumors. tlag did not discriminate carcinomas from glandular tissue. VD was higher in tumors than in the non-affected peripheral prostate (P=0.05). However, none of the dynamic parameters in carcinomas showed a significant correlation with VD or Gleason score. Although pharmacokinetic modeling in DCE MRI showed potential to discriminate prostate cancers from peripheral prostate tissue, descriptive parameters of the early signal enhancement after contrast media injection reached higher sensitivity and specificity.