Prostate cancer screening: the clinical value of diffusion-weighted imaging and dynamic MR imaging in combination with T2-weighted imaging

Diffusion-weighted magnetic resonance imaging in patients with unilateral prostate cancer on extended prostate biopsy: predictive accuracy of laterality and implications for hemi-ablative therapy

PURPOSE

We evaluated the ability of extended prostate biopsy to detect unilateral prostate cancer and assessed the incremental diagnostic benefit of diffusion-weighted magnetic resonance imaging to predict unilateral prostate cancer.

MATERIALS AND METHODS

A total of 130 patients with prostate cancer detected by extended pattern prostate biopsy underwent magnetic resonance imaging before radical prostatectomy. Tumor laterality on extended prostate biopsy was compared with the corresponding lobe on the radical prostatectomy specimen. In patients with unilateral prostate cancer on biopsy we calculated the probability of a tumor in the contralateral lobe on magnetic resonance images and calculated area under the receiver operating characteristics curve. We compared the diagnostic accuracy of combined T2-weighted and diffusion-weighted magnetic resonance images to that of T2-weighted magnetic resonance images alone.

RESULTS

Of the 130 patients 88 (67.7%) had unilateral disease on extended prostate biopsy. Radical prostatectomy pathology showed that 19% of these patients had unilateral disease but 81% had bilateral disease. Area under the receiver operating characteristics curve of combined diffusion-weighted and T2-weighted magnetic resonance imaging was greater than that of T2-weighted magnetic resonance imaging alone (0.814, 95% CI 0.716-0.889 vs 0.510, 95% CI 0.401-0.618). T2-weighted plus diffusion-weighted magnetic resonance imaging had significantly higher sensitivity (84.1% vs 61.9%, p = 0.003) and specificity (72.0% vs 36.0%, p = 0.004) to predict cancer in the contralateral lobe than T2-weighted magnetic resonance alone.

CONCLUSIONS

Extended prostate biopsy cannot accurately determine prostate cancer unilaterality. Diffusion-weighted magnetic resonance combined with T2-weighted magnetic resonance imaging has an incremental diagnostic benefit to predict unilateral prostate cancer.

Prostate cancer: differentiation of central gland cancer from benign prostatic hyperplasia by using diffusion-weighted and dynamic contrast-enhanced MR imaging

PURPOSE

To analyze the diffusion and perfusion parameters of central gland (CG) prostate cancer, stromal hyperplasia (SH), and glandular hyperplasia (GH) and to determine the role of these parameters in the differentiation of CG cancer from benign CG hyperplasia.

MATERIALS AND METHODS

In this institutional review board-approved (with waiver of informed consent), HIPAA-compliant study, 38 foci of carcinoma, 38 SH nodules, and 38 GH nodules in the CG were analyzed in 49 patients (26 with CG carcinoma) who underwent preoperative endorectal magnetic resonance (MR) imaging and radical prostatectomy. All carcinomas and hyperplastic foci on MR images were localized on the basis of histopathologic correlation. The apparent diffusion coefficient (ADC), the contrast agent transfer rate between blood and tissue (K(trans)), and extravascular extracellular fractional volume values for all carcinoma, SH, and GH foci were calculated. The mean, standard deviation, 95% confidence interval (CI), and range of each parameter were calculated. Receiver operating characteristic (ROC) and multivariate logistic regression analyses were performed for differentiation of CG cancer from SH and GH foci.

RESULTS

The average ADCs (× 10(-3) mm(2)/sec) were 1.05 (95% CI: 0.97, 1.11), 1.27 (95% CI: 1.20, 1.33), and 1.73 (95% CI: 1.64, 1.83), respectively, in CG carcinoma, SH foci, and GH foci and differed significantly, yielding areas under the ROC curve (AUCs) of 0.99 and 0.78, respectively, for differentiation of carcinoma from GH and SH. Perfusion parameters were similar in CG carcinomas and SH foci, with K(trans) yielding the greatest AUCs (0.75 and 0.58, respectively). Adding K(trans) to ADC in ROC analysis to differentiate CG carcinoma from SH increased sensitivity from 38% to 57% at 90% specificity without noticeably increasing the AUC (0.79).

CONCLUSION

ADCs differ significantly between CG carcinoma, SH, and GH, and the use of them can improve the differentiation of CG cancer from SH and GH. Combining K(trans) with ADC can potentially improve the detection of CG cancer.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100021/-/DC1.

Hexylether derivative of pyropheophorbide-a (HPPH) on conjugating with 3gadolinium(III) aminobenzyldiethylenetriaminepentaacetic acid shows potential for in vivo tumor imaging (MR, Fluorescence) and photodynamic therapy

Conjugates of 3-(1'-hexyloxyethyl)-3-devinyl pyropheophorbide-a (HPPH) with multiple Gd(III)aminobenzyl diethylenetriamine pentacetic acid (ADTPA) moieties were evaluated for tumor imaging and photodynamic therapy (PDT). In vivo studies performed in both mice and rat tumor models resulted in a significant MR signal enhancement of tumors relative to surrounding tissues at 24 h postinjection. The water-soluble (pH: 7.4) HPPH-3Gd(III) ADTPA conjugate demonstrated high potential for tumor imaging by MR and fluorescence. This agent also produced long-term tumor cures via PDT. An in vivo biodistribution study with the corresponding (14)C-analogue also showed significant tumor uptake 24 h postinjection. Toxicological evaluations of HPHH-3Gd(III)ADTPA administered at and above imaging/therapeutic doses did not show any evidence of organ toxicity. Our present study illustrates a novel approach for the development of water-soluble "multifunctional agents", demonstrating efficacy for tumor imaging (MR and fluorescence) and phototherapy.

MR Imaging of Prostate Cancer: Diffusion Weighted Imaging and (3D) Hydrogen 1 (H) MR Spectroscopy in Comparison with Histology

Purpose. To evaluate retrospectively the impact of diffusion weighted imaging (DWI) and (3D) hydrogen 1 (¹H) MR-spectroscopy (MRS) on the detection of prostatic cancer in comparison to histological examinations. Materials and Methods: 50 patients with suspicion of prostate cancer underwent a MRI examination at a 1.5T scanner. The prostate was divided into sextants. Regions of interest were placed in each sextant to evaluate the apparent diffusion coefficient (ADC)-values. The results of the DWI as well as MRS were compared retrospectively with the findings of the histological examination. Sensitivity and specificity of ADC and metabolic ratio (MET)—both separately and in combination—for identification of tumor tissue was computed for variable discrimination thresholds to evaluate its receiver operator characteristic (ROC). An association between ADC, MET and Gleason score was tested by the non-parametric Spearman ρ-test. Results. The average ADC-value was 1.65 ± 0.32mm²/s × 10⁻³ in normal tissue and 0.96±0.24 mm²/s × 10⁻³ in tumor tissue (mean ± 1 SD). MET was 0.418 ± 0.431 in normal tissue and 2.010 ± 1.649 in tumor tissue. The area under the ROC curve was 0.966 (95%-confidence interval 0.941–0.991) and 0.943 (0.918–0.968) for DWI and MRS, respectively. There was a highly significant negative correlation between ADC-value and the Gleason score in the tumor-positive tissue probes (n = 62, ρ = −0.405, P = .001). MRS did not show a significant correlation with the Gleason score (ρ = 0.117, P = .366). By using both the DWI and MRS, the regression model provided sensitivity and specificity for detection of tumor of 91.9% and 98.3%, respectively. Conclusion. The results of our study showed that both DWI and MRS should be considered as an additional and complementary tool to the T2-weighted MRI for detecting prostate cancer.

High-resolution diffusion tensor imaging of prostate cancer using a reduced FOV technique

OBJECTIVE

Diffusion tensor imaging (DTI) offers the promise of improved tumor localization in prostate cancer but the technique suffers from susceptibility-induced artifacts that limit the achievable resolution. The present work employs a reduced field-of-view technique that enables high-resolution DTI of the prostate at 3T. Feasibility of the approach is demonstrated in a clinical study including 26 patients and 14 controls.

MATERIALS AND METHODS

Reduced field-of-view acquisition was established by non-coplanar application of the excitation and the refocusing pulse in conjunction with outer volume suppression. Accuracy for cancer detection of apparent diffusion coefficient (ADC) mapping and T2-weighted imaging was calculated and compared with reference to the findings of trans-rectal ultrasound-guided octant biopsy. Mean ADCs and fractional anisotropy (FA) values in the patients with positive and negative biopsies were compared to each other and to the controls.

RESULTS

Fine anatomical details were successfully depicted on the ADC maps with sub-millimeter resolution. Accuracy for prostate cancer detection was 73.5% for ADC maps and 71% for T2-weighted images, respectively. Cohen's kappa (κ=0.48) indicated moderate agreement of the two methods. The mean ADCs were significantly lower, the FA values higher, in the patients with positive biopsy than in the patients with negative biopsy and the controls. Monte Carlo simulations showed that the FA values, but not the ADCs, were slightly overestimated. Bootstrap analysis revealed that the ADC, but not the FA value, is a highly repeatable marker.

CONCLUSION

In conclusion, the present work introduces a new approach for high-resolution DTI of the prostate enabling a more accurate detection of focal tumors especially useful in screening populations or as a potential navigator for image-guided biopsy.

Prostate cancer detection with 3 T MRI: comparison of diffusion-weighted imaging and dynamic contrast-enhanced MRI in combination with T2-weighted imaging

PURPOSE

To evaluate the diagnostic ability of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced imaging (DCEI) in combination with T2-weighted imaging (T2WI) for the detection of prostate cancer using 3 T magnetic resonance imaging (MRI) with a phased-array body coil.

MATERIALS AND METHODS

Fifty-three patients with elevated serum levels of prostate-specific antigen (PSA) were evaluated by T2WI, DWI, and DCEI prior to needle biopsy. The obtained data from T2WI alone (protocol A), a combination of T2WI and DWI (protocol B), a combination T2WI and DCEI (protocol C), and a combination of T2WI plus DWI and DCEI (protocol D) were subjected to receiver operating characteristic (ROC) curve analysis.

RESULTS

The sensitivity, specificity, accuracy, and area under the ROC curve (Az) for region-based analysis were: 61%, 91%, 84%, and 0.8415, respectively, in protocol A; 76%, 94%, 90%, and 0.8931, respectively, in protocol B; 77%, 93%, 89%, and 0.8655, respectively, in protocol C; and 81%, 96%, 92%, and 0.8968, respectively in protocol D. ROC analysis revealed significant differences between protocols A and B (P = 0.0008) and between protocols A and D (P = 0.0004).

CONCLUSION

In patients with elevated PSA levels the combination of T2WI, DWI, DCEI using 3 T MRI may be a reasonable approach for the detection of prostate cancer.

Supervised and unsupervised methods for prostate cancer segmentation with multispectral MRI

PURPOSE

Magnetic resonance imaging (MRI) has been proposed as a promising alternative to transrectal ultrasound for the detection and localization of prostate cancer and fusing the information from multispectral MR images is currently an active research area. In this study, the goal is to develop automated methods that combine the pharmacokinetic parameters derived from dynamic contrast enhanced (DCE) MRI with quantitative T2 MRI and diffusion weighted imaging (DWI) in contrast to most of the studies which were performed with human readers. The main advantages of the automated methods are that the observer variability is removed and easily reproducible results can be efficiently obtained when the methods are applied to a test data. The goal is also to compare the performance of automated supervised and unsupervised methods for prostate cancer localization with multispectral MRI.

METHODS

The authors use multispectral MRI data from 20 patients with biopsy-confirmed prostate cancer patients, and the image set consists of parameters derived from T2, DWI, and DCE-MRI. The authors utilize large margin classifiers for prostate cancer segmentation and compare them to an unsupervised method the authors have previously developed. The authors also develop thresholding schemes to tune support vector machines (SVMs) and their probabilistic counterparts, relevance vector machines (RVMs), for an improved performance with respect to a selected criterion. Moreover, the authors apply a thresholding method to make the unsupervised fuzzy Markov random fields method fully automatic.

RESULTS

The authors have developed a supervised machine learning method that performs better than the previously developed unsupervised method and, additionally, have found that there is no significant difference between the SVM and RVM segmentation results. The results also show that the proposed methods for threshold selection can be used to tune the automated segmentation methods to optimize results for certain criteria such as accuracy or sensitivity. The test results of the automated algorithms indicate that using multispectral MRI improves prostate cancer segmentation performance when compared to single MR images, a result similar to the human reader studies that were performed before.

CONCLUSIONS

The automated methods presented here can help diagnose and detect prostate cancer, and improve segmentation results. For that purpose, multispectral MRI provides better information about cancer and normal regions in the prostate when compared to methods that use single MRI techniques; thus, the different MRI measurements provide complementary information in the automated methods. Moreover, the use of supervised algorithms in such automated methods remain a good alternative to the use of unsupervised algorithms.

Multi-parametric MR imaging of transition zone prostate cancer: Imaging features, detection and staging

Magnetic resonance (MR) imaging has been increasingly used in the evaluation of prostate cancer. As studies have suggested that the majority of cancers arise from the peripheral zone (PZ), MR imaging has focused on the PZ of the prostate gland thus far. However, a considerable number of cancers (up to 30%) originate in the transition zone (TZ), substantially contributing to morbidity and mortality. Therefore, research is needed on the TZ of the prostate gland. Recently, MR imaging and advanced MR techniques have been gaining acceptance in evaluation of the TZ. In this article, the MR imaging features of TZ prostate cancers, the role of MR imaging in TZ cancer detection and staging, and recent advanced MR techniques will be discussed in light of the literature.

[Clinical value of diffusion-weighted magnetic resonance imaging for localization of prostate cancer--comparison with the step sections of radical prostatectomy]

PURPOSE

The objective of our study was to compare T2-weighted magnetic resonance imaging (T2WI), combined T2-weighted and dynamic imaging (Dynamic), and combined T2-weighted and diffusion-weighted imaging (DWI) in the identification of the site of prostate cancer.

MATERIALS AND METHODS

Before radical prostatectomy, 85 patients with prostate cancer underwent magnetic resonance imaging using a 1.5-T endorectal coil; we excluded 3 patients treated with neoadjuvant hormonal therapy. The sites of prostate cancer in 82 patients were predicted by T2WI alone, T2WI + Dynamic, and T2WI + DWI, and the results were compared with the step-section analysis of radical prostatectomy specimens. The peripheral zone (PZ) and the transition zone (TZ) of the prostate were divided into left and right halves. Only tumors with a diameter of more than 5 mm were considered significant.

RESULTS

The sensitivity, specificity, positive predictive value (PPV), and the area under the receiver operating characteristic (ROC) curve (Az) for the prediction of the site of prostate cancer in the PZ of the prostate were as follows: 42%, 94%, 93%, and 0.76 for T2WI alone; 48%, 96%, 96%, and 0.78 for T2WI + Dynamic; and 50%, 96%, 96%, and 0.81 for T2WI + DWI. The sensitivity, specificity, PPV, and Az for the prediction of the site of prostate cancer in the TZ of the prostate were as follows: 31%, 92%, 76%, and 0.66 for T2WI alone; 46%, 82%, 67%, and 0.65 for T2WI + Dynamic; and 48%, 94%, 85%, and 0.71 for T2WI + DWI.

CONCLUSION

The Az value for the prediction of prostate cancer in the PZ and those in the TZ of the prostate was the highest for the combined T2WI and DWI approach.

Whole-body diffusion-weighted imaging vs. FDG-PET for the detection of non-small-cell lung cancer. How do they measure up?

OBJECTIVE

To compare the diagnostic efficacy of whole-body diffusion-weighted imaging (WB-DWI) and [18F] fluoro-2-D-glucose PET/CT(FDG-PET/CT)for assessment of non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

A group of 56 patients (21 female, 35 male; 35-76 years) with NSCLC proved by pathologic examination or follow-up imaging findings was set as reference standards, and all patients underwent both WB-DWI at 1.5T (MAGNETOM Avanto) and PET/CT (Biograph 16). For WB-DWI, a free breathing diffusion-weighted single-shot spin-echo epi-sequence in five-stations (head-neck, thorax, abdomen, pelvis-thigh) was used. Each station-series contained 30 contiguous axial slices. Imaging parameters: FOV 360x360 mm, matrix size 128x80. B-values: 0 and 1000 s/mm(2) applied along x, y and z, 5 averages, acquisition time: 2.23 min/series, total: 11.55 min. The efficacy of WB-DWI and PET/CT were determined in a blinded reading by two radiologists and two nuclear medicine physicians using pathology and size change during follow up exams as the reference standard.

RESULTS

Primary tumors (n=56 patients) were correctly detected in 56 (100%) patients by both PET/CT and WB-DWI. Ninety-six lymph nodes metastases were determined with pathologic and follow-up examinations. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) being for lymph node metastases: 91%, 90%, 90%, 96%, 80% with WB-DWI and 98%, 97%, 97%, 99%, 93% with PET-CT, other metastases: 90%, 95%, 92%, 97%, 83% with WB-DWI and 98%, 100%, 98%, 100%, 95% with PET-CT). Differences in the accuracy of lymph node metastasis detection between PET/CT and WB-DWI (P=.031) were significant. The differences were not statistically significant for detection of other metastases.

CONCLUSIONS

WB-DWI is a feasible clinical technique for the assessment of NSCLC, lymph nodes and metastastic spread with high sensitivity and accuracy, but it was limited in the evaluation of neck lymph node metastases and small metastastic lung nodules.

Modalities for imaging of prostate cancer

Prostate cancer is the second most common cause of cancer deaths among males in the United States. Prostate screening by digital rectal examination and prostate-specific antigen has shifted the diagnosis of prostate cancer to lower grade, organ confined disease, adding to overdetection and overtreatment of prostate cancer. The new challenge is in differentiating clinically relevant tumors from ones that may otherwise never have become evident if not for screening. The rapid evolution of imaging modalities and the synthesis of anatomic, functional, and molecular data allow for improved detection and characterization of prostate cancer. However, the appropriate use of imaging is difficult to define, as many controversial studies regarding each of the modalities and their utilities can be found in the literature. Clinical practice patterns have been slow to adopt many of these advances as a result. This review discusses the more established imaging techniques, including Ultrasonography, Magnetic Resonance Imaging, MR Spectroscopy, Computed Tomography, and Positron Emission Tomography. We also review several promising techniques on the horizon, including Dynamic Contrast-Enhanced MRI, Diffuse-Weighted Imaging, Superparamagnetic Nanoparticles, and Radionuclide Scintigraphy.

Update on prostate imaging

Successful and accurate imaging of prostate cancer is integral to its clinical management from detection and staging to subsequent monitoring. Various modalities are used including ultrasound, computed tomography, and magnetic resonance imaging, with the greatest advances seen in the field of magnetic resonance.

[Diffusion-weighted MR imaging of the prostate]

Functional imaging complements T2-weighted imaging in the evaluation of the prostate. The most frequently used techniques are diffusion-weighted imaging and perfusion imaging following the intravenous administration of contrast material. Perfusion imaging has high sensitivity and moderate specificity, even when using a quantitative technique, because contrast kinetics in some cases of peripheral zone prostatitis and benign transition zone hyperplasia may simulate cancer. Diffusion-weighted imaging is currently under evaluation but appears to be preferable to dynamic perfusion MR imaging because of its higher specificity and simpler acquisition. Functional imaging of the prostate is performed to detect cancers missed on biopsies or evaluate the volume of a newly diagnosed clinically localized cancer to assist in therapy selection. Future applications for image-guidance of targeted therapies to the tumor are currently investigational.

Multidisciplinary functional MR imaging for prostate cancer

Various functional magnetic resonance (MR) imaging techniques are used for evaluating prostate cancer including diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and MR spectroscopy. These techniques provide unique information that is helpful to differentiate prostate cancer from non-cancerous tissue and have been proven to improve the diagnostic performance of MRI not only for cancer detection, but also for staging, post-treatment monitoring, and guiding prostate biopsies. However, each functional MR imaging technique also has inherent challenges. Therefore, in order to make accurate diagnoses, it is important to comprehensively understand their advantages and limitations, histologic background related with image findings, and their clinical relevance for evaluating prostate cancer. This article will review the basic principles and clinical significance of functional MR imaging for evaluating prostate cancer.

Technologies for localization and diagnosis of prostate cancer

The gold standard for detecting prostate cancer (PCa), systematic biopsy, lacks sensitivity as well as grading accuracy. PSA screening leads to over-treatment of many men, and it is unclear whether screening reduces PCa mortality. This review provides an understanding of the difficulties of localizing and diagnosing PCa. It summarizes recent developments of ultrasound (including elastography) and MRI, and discusses some alternative experimental techniques, such as resonance sensor technology and vibrational spectroscopy. A comparison between the different methods is presented. It is concluded that new ultrasound techniques are promising for targeted biopsy procedures, in order to detect more clinically significant cancers while reducing the number of cores. MRI advances are very promising, but MRI remains expensive and MR-guided biopsy is complex. Resonance sensor technology and vibrational spectroscopy have shown promising results in vitro. There is a need for large prospective multicentre trials that unambiguously prove the clinical benefits of these new techniques.

Magnetic resonance imaging guided prostate biopsy in men with repeat negative biopsies and increased prostate specific antigen

PURPOSE

Undetected cancer in repeat transrectal ultrasound guided prostate biopsies in patients with increased prostate specific antigen greater than 4 ng/ml is a considerable concern. We investigated the tumor detection rate of tumor suspicious regions on multimodal 3 Tesla magnetic resonance imaging and subsequent magnetic resonance imaging guided biopsy in 68 men with repeat negative transrectal ultrasound guided prostate biopsies. We compared results to those in a matched transrectal ultrasound guided prostate biopsy population. Also, we determined the clinical significance of detected tumors.

MATERIALS AND METHODS

A total of 71 consecutive patients with prostate specific antigen greater than 4 ng/ml and 2 or greater negative transrectal ultrasound guided prostate biopsy sessions underwent multimodal 3 Tesla magnetic resonance imaging. In 68 patients this was followed by magnetic resonance imaging guided biopsy directed toward tumor suspicious regions. A matched multisession transrectal ultrasound guided prostate biopsy population from our institutional database was used for comparison. The clinical significance of detected tumors was established using accepted criteria, including prostate specific antigen, Gleason grade, stage and tumor volume.

RESULTS

The tumor detection rate of multimodal 3 Tesla magnetic resonance imaging guided biopsy was 59% (40 of 68 cases) using a median of 4 cores. The tumor detection rate was significantly higher than that of transrectal ultrasound guided prostate biopsy in all patient subgroups (p <0.01) except in those with prostate specific antigen greater than 20 ng/ml, prostate volume greater than 65 cc and prostate specific antigen density greater than 0.5 ng/ml/cc, in which similar rates were achieved. Of the 40 patients with identified tumors 37 (93%) were considered highly likely to harbor clinically significant disease.

CONCLUSIONS

Multimodal magnetic resonance imaging is an effective technique to localize prostate cancer. Magnetic resonance imaging guided biopsy of tumor suspicious regions is an accurate method to detect clinically significant prostate cancer in men with repeat negative biopsies and increased prostate specific antigen.

In vivo MR elastography of the prostate gland using a transurethral actuator

Conventional approaches for MR elastography (MRE) using surface drivers have difficulty achieving sufficient shear wave propagation in the prostate gland due to attenuation. In this study we evaluate the feasibility of generating shear wave propagation in the prostate gland using a transurethral device. A novel transurethral actuator design is proposed, and the performance of this device was evaluated in gelatin phantoms and in a canine prostate gland. All MRI was performed on a 1.5T MR imager using a conventional gradient-echo MRE sequence. A piezoceramic actuator was used to vibrate the transurethral device along its length. Shear wave propagation was measured transverse and parallel to the rod at frequencies between 100 and 250 Hz in phantoms and in the prostate gland. The shear wave propagation was cylindrical, and uniform along the entire length of the rod in the gel experiments. The feasibility of transurethral MRE was demonstrated in vivo in a canine model, and shear wave propagation was observed in the prostate gland as well as along the rod. These experiments demonstrate the technical feasibility of transurethral MRE in vivo. Further development of this technique is warranted.

Prostate cancer detection with multi-parametric MRI: logistic regression analysis of quantitative T2, diffusion-weighted imaging, and dynamic contrast-enhanced MRI

PURPOSE

To develop a multi-parametric model suitable for prospectively identifying prostate cancer in peripheral zone (PZ) using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twenty-five radical prostatectomy patients (median age, 63 years; range, 44-72 years) had T2-weighted, diffusion-weighted imaging (DWI), T2-mapping, and dynamic contrast-enhanced (DCE) MRI at 1.5 Tesla (T) with endorectal coil to yield parameters apparent diffusion coefficient (ADC), T2, volume transfer constant (K(trans)) and extravascular extracellular volume fraction (v(e)). Whole-mount histology was generated from surgical specimens and PZ tumors delineated. Thirty-eight tumor outlines, one per tumor, and pathologically normal PZ regions were transferred to MR images. Receiver operating characteristic (ROC) curves were generated using all identified normal and tumor voxels. Step-wise logistic-regression modeling was performed, testing changes in deviance for significance. Areas under the ROC curves (A(z)) were used to evaluate and compare performance.

RESULTS

The best-performing single-parameter was ADC (mean A(z) [95% confidence interval]: A(z,ADC): 0.689 [0.675, 0.702]; A(z,T2): 0.673 [0.659, 0.687]; A(z,Ktrans): 0.592 [0.578, 0.606]; A(z,ve): 0.543 [0.528, 0.557]). The optimal multi-parametric model, LR-3p, consisted of combining ADC, T2 and K(trans). Mean A(z,LR-3p) was 0.706 [0.692, 0.719], which was significantly higher than A(z,T2), A(z,Ktrans), and A(z,ve) (P < 0.002). A(z,LR-3p) tended to be greater than A(z,ADC), however, this result was not statistically significant (P = 0.090).

CONCLUSION

Using logistic regression, an objective model capable of mapping PZ tumor with reasonable performance can be constructed.

Detection of bone metastases in non-small cell lung cancer patients: comparison of whole-body diffusion-weighted imaging (DWI), whole-body MR imaging without and with DWI, whole-body FDG-PET/CT, and bone scintigraphy

PURPOSE

To prospectively compare the capability for bone metastasis assessment of whole-body diffusion-weighted imaging (DWI), magnetic resonance imaging (MRI) without and with DWI, [(18)F] fluoro-2-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) and bone scintigraphy in non-small cell carcinoma (NSCLC) patients.

MATERIALS AND METHODS

In all, 115 consecutive NSCLC patients (66 men, 49 women; mean age 72 years) prospectively underwent whole-body MRI, PET/CT, and bone scintigraphy before treatment. For each method, probability of metastasis was independently assessed by using a 5-point visual scoring system on a per-site basis. Receiver operating characteristic (ROC)-based positive tests were used to determine the practical threshold value for each method on a per-site basis. Sensitivities, specificities, and accuracies were then compared on a per-site and per-patient basis by means of McNemar's test.

RESULTS

When the practical threshold values were adapted, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy and PET/CT (P < 0.05). On a per-patient basis, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy (P < 0.05).

CONCLUSION

Whole-body MRI with DWI can be used for bone metastasis assessment of NSCLC patients as accurate as bone scintigraphy and/or PET/CT.

Diffusion-weighted imaging of surgically resected hepatocellular carcinoma: imaging characteristics and relationship among signal intensity, apparent diffusion coefficient, and histopathologic grade

OBJECTIVE

The objective of our study was to determine the relationship between the signal intensity of hepatocellular carcinoma (HCC) assessed with diffusion-weighted imaging (DWI) and T2-weighted imaging and the apparent diffusion coefficient (ADC) with the histopathologic grade of each nodule.

MATERIALS AND METHODS

MR examinations including DWI and T2-weighted imaging of 125 surgically resected hypervascular HCCs in 99 patients were retrospectively reviewed. Pathologic examinations revealed 25 well-, 61 moderately, and 39 poorly differentiated HCCs. Two radiologists reviewed the images and classified the signal intensity of each tumor on DWI and T2-weighted imaging by mutual agreement. The incidence of each signal intensity and the relationship between signal intensity and histopathologic grade were assessed for each sequence. The relationship between the ADC and histopathologic grade was also evaluated.

RESULTS

On DWI, 11 of 125 HCCs appeared hypo- to isointense, 27 tumors appeared slightly hyperintense, and the remaining 87 tumors appeared obviously hyperintense to the surrounding liver. Overall, 91.2% (114/125) of HCCs showed hyperintensity to the surrounding hepatic parenchyma. Statistical analysis showed that this rate on DWI was significantly higher than that on T2 turbo spin-echo (TSE) imaging (p < 0.001). On DWI, the tumors tended to show a brighter signal with rising histopathologic grade (p = 0.031), but this trend was not observed on T2-weighted imaging. ADC measurements revealed that the mean ADCs of well-, moderately, and poorly differentiated HCCs were approximately 1.45, 1.46, and 1.36 x 10(-3) mm(2)/s, respectively. There was no significant correlation between ADC and histopathologic grade.

CONCLUSION

The histopathologic grade of HCC had no correlation with the ADC, but HCC tumors tended to show a higher signal on DWI as the histopathologic grade rose. However, predicting the correct histopathologic grade of each HCC before surgery on the basis of DWI findings was difficult because of the large overlap among histopathologic grades.

Diffusion-weighted imaging with apparent diffusion coefficient mapping and spectroscopy in prostate cancer

Prostate cancer is a major health problem, and the exploration of noninvasive imaging methods that have the potential to improve specificity while maintaining high sensitivity is still critically needed. Tissue changes induced by tumor growth can be visualized by magnetic resonance imaging (MRI) methods. Current MRI methods include conventional T2-weighted imaging, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping and magnetic resonance spectroscopy (MRS). Techniques such as DWI/ADC provide functional information about the behavior of water molecules in tissue; MRS can provide biochemical information about the presence or absence of certain metabolites, such as choline, creatine, and citrate. Finally, vascular parameters can be investigated using dynamic contrast-enhanced MRI. Moreover, with whole-body MRI and DWI, metastatic disease can be evaluated in 1 session and may provide a way to monitor treatment. Therefore, when combining these various methods, a multiparametric data set can be built to assist in the detection, localization, assessment of prostate cancer aggressiveness, and tumor staging. Such a comprehensive approach offers more power to evaluate prostate disease than any single measure alone. In this article, we focus on the role of DWI/ADC and MRS in the detection and characterization using both in vivo and ex vivo imaging of prostate pathology.

Diffusion-weighted imaging of prostate cancer: correlation between apparent diffusion coefficient values and tumor proliferation

PURPOSE

To investigate whether the apparent diffusion coefficient (ADC) values of prostate cancer (PCa) are able to reflect tumor proliferation.

MATERIALS AND METHODS

The clinical and pathological information for 38 patients with PCa and 33 patients with benign prostate hyperplasia (BPH) were studied. Examination of the patients was performed using a 1.5 T superconducting magnetic scanner equipped with a pelvic phased-array multicoil. Diffusion-weighted images (DWIs) were acquired using an echo-planar imaging sequence. The ADC values of PCa, BPH, and peripheral zone (PZ) were calculated. The cellularity of PCa was recorded based on hematoxylin and eosin staining. The proliferating cell nuclear antigen (PCNA) was detected using an immunohistochemical technique.

RESULTS

The ADC values of PCa, BPH, and PZ were 49.32 +/- 12.68 x 10(-5) mm(2)/s, 86.73 +/- 26.75 x 10(-5) mm(2)/s, and 126.25 +/- 27.21 x 10(-5) mm(2)/s, respectively. The ADC values of PCa were lower than those of BPH and PZ (P < 0.05). The cellularity and PCNA labeling index (LI) of PCa were higher than those of BPH (P < 0.05). The ADC values of PCa were negatively correlated with those of cellularity and PCNA LI (r = -0.646 and -0.446, respectively; P < 0.05).

CONCLUSION

The ADC values of PCa can reveal the differences in proliferative activity between PCa and BPH. These values are therefore able to predict the proliferative rate of variously differentiated prostate cancers.

The role of the ADC value in the characterisation of renal carcinoma by diffusion-weighted MRI

The purpose of this study is to evaluate the role of diffusion-weighted imaging (DWI) in combination with T(1) and T(2) weighted MRI for the characterisation of renal carcinoma. The institutional review board approved the study protocols and waived informed consent from all of the patients. 47 patients (32 male and 15 female; age range, 21-85 years; median age, 65 years) who had suspected renal lesions on abdominal CT underwent MRI for further evaluation and characterisation of the lesions from April 2005 to August 2007 in our university hospital. A region of interest was drawn around the tumour area on apparent diffusion coefficient (ADC) maps. Final diagnosis was confirmed by histological examination of surgical specimens from all patients. The ADC value was significantly higher in renal cell carcinoma (RCC) than in transitional cell carcinoma (2.71+/-2.35 x 10(-3) mm(2) s(-1) vs 1.61+/-0.80 x 10(-3) mm(2) s(-1); p = 0.022). While analysing the histological subtypes of RCC, a significant difference in ADC values between clear cell carcinoma and non-clear cell carcinoma was found (1.59+/-0.55 x 10(-3) mm(2) s(-1) vs 6.72+/-1.85 x 10(-3) mm(2) s(-1); p = 0.0004). Similarly, ADC values of RCC revealed a significant difference between positive and negative metastatic lesions (1.06+/-0.38 x 10(-3) mm(2) s(-1) vs 3.02+/-2.44 x 10(-3) mm(2) s(-1); p = 0.0004), whereas intensity on T(1) and T(2) weighted imaging did not reach statistical significance. In conclusion, DWI has clinical value in the characterisation of renal carcinomas and could be applied in clinical practice for their management.

Is it time to consider a role for MRI before prostate biopsy?

The use of MRI in prostate cancer management is controversial and current guidelines underplay its role. Technological advances over the past 5 years, however, demand a re-evaluation of this position. In this article, we propose an increased use of MRI, not only in those with a diagnosis of prostate cancer but also for men before a prostate biopsy. The use of MRI before a biopsy can serve as a triage test in men with raised serum prostate-specific antigen levels, in order to select those for biopsy with significant cancer that requires treatment. This strategy could avoid biopsy, and hence unnecessary treatment, in those with no disease or insignificant cancer. In addition, avoidance of postbiopsy artifact caused by hemorrhage will lead to better local staging accuracy, while determining more accurately the disease burden. This approach could improve risk stratification by selecting those who require adjuvant therapy or dose escalation. Furthermore, MRI evaluation of cancer burden could be important in active surveillance regimens to select those needing intervention.

Current status of MRI for the diagnosis, staging and prognosis of prostate cancer: implications for focal therapy and active surveillance

PURPOSE OF REVIEW

To review the current status of MRI techniques in identification of organ-confined prostate cancer with a focus on their implication for focal therapy and active surveillance.

RECENT FINDINGS

MRI is currently focusing on intraprostatic prostate cancer identification and at 1.5T, it provides excellent imaging of the whole gland including the challenging anterior part. Improvements in accuracy for cancer detection and volume estimation result from dynamic contrast-enhanced and diffusion-weighted MRI sequences. 3T MRI might improve cancer identification. Histological correlations showed high sensitivity and specificity for significant volume cancers larger than 0.5 cm3. Important knowledge on modelling of cancer morphology such as zone of origin and intraprostatic patterns of spread at histopathology was made available for imaging interpretation and treatment planning decision. MRI results allow focused use of biopsy which led to better cancer characterization such as extent and grade. Ongoing focal therapy protocols and active surveillance treatments should benefit from these imaging advances.

SUMMARY

At present, high-resolution MRI with pelvic coil appears to offer the most readily available and useful imaging. Future studies should work towards helping define standard, reproducible approaches to imaging and image reporting for research and clinical practice.

Synthesis of bombesin-functionalized iron oxide nanoparticles and their specific uptake in prostate cancer cells

The imaging of molecular markers associated with disease offers the possibility for earlier detection and improved treatment monitoring. Receptors for gastrin-releasing peptide are overexpressed on prostate cancer cells offering a promising imaging target, and analogs of bombesin, an amphibian tetradecapeptide have been previously demonstrated to target these receptors. Therefore, the pan-bombesin analog [β-Ala11, Phe13, Nle14]bombesin-(7-14) was conjugated through a linker to dye-functionalized superparamagnetic iron oxide nanoparticles for the development of a new potential magnetic resonance imaging probe. The peptide was conjugated via click chemistry, demonstrating a complementary alternative methodology to conventional peptide-nanoparticle conjugation strategies. The peptide-functionalized nanoparticles were then demonstrated to be selectively taken up by PC-3 prostate cancer cells relative to unfunctionalized nanoparticles and this uptake was inhibited by the presence of free peptide, confirming the specificity of the interaction. This study suggests that these nanoparticles have the potential to serve as magnetic resonance imaging probes for the detection of prostate cancer.

New horizons in prostate cancer imaging

Prostate cancer is the most common non-cutaneous malignancy among American men. Imaging has recently become more important in detection of prostate cancer since screening techniques such as digital rectal examination (DRE), prostate specific and transrectal ultrasound guided biopsy have considerable limitations in diagnosis and localization of prostate cancer. In this manuscript, we reviewed conventional, functional and targeted imaging modalities used in diagnosis and local staging of prostate cancer with exquisite images.

Dynamic contrast-enhanced magnetic resonance imaging in prostate cancer

Prostate cancer remains a major health concern for the male population. During the past decade, a dramatic increase in prostate-specific antigen and transurethral resection of the prostate has resulted in increased detection rate of small lesions and increased incidence of this disease. Needle biopsies in asymptomatic men have also contributed to the increased incidence of prostate cancer, leading to an increasing incidence-to-mortality ratio. Magnetic resonance imaging (MRI) is the modality of choice in prostate cancer patients with increased prostate-specific antigen levels before or after prostate cancer diagnosis confirmed by biopsy and T2-weighted imaging (T2W) has been used as a standard technique in detection. During the last decade, dynamic contrast-enhanced MRI has emerged as one of the main techniques used in multiparametric MRI of the prostate gland in cancer patients. Dynamic contrast-enhanced MRI has been routinely used for detection and diagnosis of the tumor, for staging and monitoring the therapeutic response, as well as for guiding targeted biopsies in patients with suspected prostate cancer or with a negative biopsy result. In this article, we are going to review the analysis techniques of dynamic contrast-enhanced MRI and its various clinical applications in prostate cancer patients.

Functional magnetic resonance imaging in prostate cancer

CONTEXT

Magnetic resonance imaging (MRI) combined with magnetic resonance spectroscopy imaging (MRSI), dynamic contrast-enhanced MRI, and diffusion-weighted MRI emerged as promising tests in the diagnosis of prostate cancer, and they show encouraging results.

OBJECTIVE

This review emphasizes different functional MRI techniques in the diagnosis of prostate cancer and includes information about their clinical value and usefulness.

EVIDENCE ACQUISITION

The authors searched the Medline, Embase, and Cochrane Library databases. There were no language restrictions. The last search was performed in October 2008.

EVIDENCE SYNTHESIS

The combination of conventional MRI with functional MRI techniques is more reliable for differentiating benign and malignant prostate tissues than any other diagnostic procedure. At present, no guideline is available that outlines which technique is best in a specific clinical situation. It also remains uncertain whether improved spatial resolution and signal-to-noise ratio of 3-T MRI will improve diagnostic performance.

CONCLUSIONS

A limited number of small studies suggest that functional MRI may improve the diagnosis and staging of prostate cancer. This finding needs further confirmation in larger studies, and cost-effectiveness needs to be established.

Thirty-two-channel coil 3T magnetic resonance-guided biopsies of prostate tumor suspicious regions identified on multimodality 3T magnetic resonance imaging: technique and feasibility

OBJECTIVES

To test the technique and feasibility of translating tumor suspicious region maps in the prostate, obtained by multimodality, anatomic, and functional 3T magnetic resonance imaging (MRI) data to 32-channel coil, T2-weighted (T2-w), 3T MR images, for directing MR-guided biopsies. Furthermore, to evaluate the practicability of MR-guided biopsy on a 3T MR scanner using a 32-channel coil and a MR-compatible biopsy device.

MATERIALS AND METHODS

Twenty-one patients with a high prostate-specific antigen (>4.0 ng/mL) and at least 2 prior negative transrectal ultrasound-guided biopsies of the prostate underwent an endorectal coil 3T MRI, which included T2-w, diffusion weighted and dynamic contrast enhanced MRI. From these multimodality images, tumor suspicious regions (TSR) were determined. The 3D localization of these TSRs within the prostatic gland was translated to the T2-w MR images of a subsequent 32-channel coil 3T MRI. These were then biopsied under 3T MR guidance.

RESULTS

In all patients, TSRs could be identified and accurately translated to subsequent 3T MR images and biopsied under MR guidance. Median MR biopsy procedure time was 35 minutes. Of the 21 patients, 8 (38%) were diagnosed with prostate cancer, 6 (29%) had evidence of prostatitis, 6 (29%) had combined inflammatory and atrophic changes, and only 1 (5%) patient had no identifiable pathology.

CONCLUSIONS

Multimodality, 3T MRI determined TSRs could effectively be translated to T2-weighted images, to be used for MR biopsies. 3T MR-guided biopsy based on these translated TSRs was feasible, performed in a clinical useful time, and resulted in a high number of positive results.

Diffusion and perfusion MR imaging of the prostate

Conventional anatomic MR imaging has evolved to a superior modality in the evaluation of prostate carcinoma and is now a widely established technique in the detection and staging of this disease, aiding in clinical decision making on treatment and therapy evaluation. Recent improvements in functional MR techniques, such as diffusion-weighted MR imaging and dynamic contrast-enhanced MR imaging, have greatly increased the impact of MR imaging in prostate cancer. The combination of T2-weighted imaging, diffusion-weighted MR imaging, and dynamic contrast-enhanced MR imaging may overcome the limitations of conventional T2-weighted MR imaging of the prostate and may be able accurately to detect, localize, stage, and grade prostate carcinoma and guide biopsies.

Lesion localization in patients with a previous negative transrectal ultrasound biopsy and persistently elevated prostate specific antigen level using diffusion-weighted imaging at three Tesla before rebiopsy

OBJECTIVE

To assess the use of diffusion-weighted imaging (DWI) at 3 Tesla (T) for lesion localization in patients with a high risk of prostate cancer before a rebiopsy.

MATERIALS AND METHODS

A total of 43 patients (age range, 40-80 years; mean age, 62.6 years) who had previously undergone a transrectal ultrasound (TRUS)-guided biopsy that was negative and continued to have a persistent elevated prostate specific antigen level underwent DWI with b = 0 s/mm and b = 1000 s/mm before a rebiopsy. We located the area of the lowest apparent diffusion coefficient values and performed a target biopsy of that area, followed by a systematic biopsy under TRUS guidance. We evaluated the cancer detection rate, tumor location, and lesion visibility on T2-weighted imaging (T2WI) in patients with biopsy-proven cancers.

RESULTS

Prostate cancer was detected in 17 (39.5%) patients, and was more predominant in the transitional zone (76.4%, 13/17) than in the peripheral zone (23.6%, 4/17) (P < 0.05). Of the 17 cancers detected on DWI, 6 lesions were seen on T2WI.

CONCLUSION

DWI in addition to T2WI at 3 T has the potential to provide important information on lesion localization in patients that had both previous negative TRUS biopsy and persistently elevated prostate specific antigen levels before a repeated biopsy.

High b-value diffusion-weighted imaging in normal and malignant peripheral zone tissue of the prostate: effect of signal-to-noise ratio

PURPOSE

To determine whether the apparent diffusion coefficient (ADC) obtained using a high b-value (2,000 s/mm2) is superior to that using a standard b-value (1,000 s/mm2) for discriminating malignant from normal peripheral tissue in the prostate.

METHODS

Twenty-six patients with biopsy-proven prostate cancer underwent 1.5T magnetic resonance (MR) imaging including single-shot, echo-planar diffusion-weighted imaging (DWI) with repetition time/echo time, 3500/88 ms; 4-mm slice thickness; 1-mm interslice gap; 144x128 matrix; field of view, 250x250 mm; number of excitations, 10; and b-values, 0, 1,000, and 2,000 s/mm2. For each patient, ADC values were obtained for malignant and normal tissue using b=1,000 and 2,000 in a monoexponential model. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios in DWI were also evaluated.

RESULTS

At b=1,000, the mean ADC (x10(-3) mm2/s) for malignant tissue was 0.82+/-0.27 (range 0.43-1.29) and for normal tissue, 1.69+/-0.23 (1.31-2.18). At b=2000, the mean ADC for malignant tissue was 0.61+/-0.19 (0.30-0.94) and for normal tissue, 1.01+/-0.14 (0.73-1.35). Significant ADC overlap between the malignant and normal tissue was recognized at b=2000. As b-value increased, the mean SNR within malignant tissue decreased by 21.6%, and mean CNR decreased 17.3%.

CONCLUSIONS

Under the same imaging conditions, measuring ADC using a high b-value (2,000 s/mm2) in a monoexponential model has little diagnostic advantage over using the standard b-value (1,000 s/mm2) in discriminating malignant from normal prostate tissue.