Perfusion MR Imaging: Clinical Utility for the Differential Diagnosis of Various Brain Tumors

Objective

To determine the utility of perfusion MR imaging in the differential diagnosis of brain tumors.

Materials and Methods

Fifty-seven patients with pathologically proven brain tumors (21 high-grade gliomas, 8 low-grade gliomas, 8 lymphomas, 6 hemangioblastomas, 7 metastases, and 7 various other tumors) were included in this study. Relative cerebral blood volume (rCBV) and time-to-peak (TTP) ratios were quantitatively analyzed and the rCBV grade of each tumor was also visually assessed on an rCBV map.

Results

The highest rCBV ratios were seen in hemangioblastomas, followed by high-grade gliomas, metastases, low-grade gliomas, and lymphomas. There was no significant difference in TTP ratios between each tumor group (p>0.05). At visual assessment, rCBV was high in 17 (81%) of 21 high-grade gliomas and in 4 (50%) of 8 low-grade gliomas. Hemangioblastomas showed the highest rCBV and lymphomas the lowest.

Conclusion

Perfusion MR imaging may be helpful in the differentiation of thevarious solid tumors found in the brain, and in assessing the grade of the various glial tumors occurring there.     

Factors influencing the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography: correlation with biopsy and radical prostatectomy specimens

Objectives

This study was designed to identify factors that influenced the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography (CETRUS).

Methods

139 patients suspected of prostate cancer were evaluated with CETRUS followed by systematic and targeted transrectal ultrasound-guided biopsies. The degree of enhancement of the lesions was objectively measured using peak intensity with time–intensity curve analysis software. Ultrasound findings were correlated with clinical characteristics as well as biopsy and radical prostatectomy findings.

Results

Prostate cancers were detected in 230 biopsy sites from 91 patients. The mean peak intensity value of prostate cancer was significantly higher than that of the benign lesions (9.82±3.73 vs 7.51±2.97; p<0.001), and the peak intensity value of the cancer foci varied across the prostate. The mixed model analysis revealed that the location and Gleason score of tumour foci were the influencing factors of the peak intensity value, and the former had a stronger influence upon peak intensity than the latter (p=0.000 and 0.040, respectively). However, age, prostate volume or serum prostate-specific antigen of the patient had no significant influence on the peak intensity value (p>0.05). Furthermore, the peak intensity value of tumours larger than 5 mm diameter was significantly higher than tumours of 5 mm or smaller diameter (9.28±2.46 vs 6.69±2.65; p<0.001).

Conclusions

The prostate cancer lesions with a higher Gleason score and larger tumour size which were located in the lateral peripheral zone (PZ) were more likely to show a marked enhancement. Lesions with lower peak intensity that are located in the medial PZ should also be treated as suspicious.Prostate cancer is the most commonly diagnosed cancer in males, accounting for 28% of new cancer diagnoses in males and 11% of cancer-related deaths, with an expected 32 050 prostate cancer-specific mortalities in 2010 [1]. The imaging of prostate cancer is central to early detection and staging. However, it is generally acknowledged that detection and localisation of prostate tumours using greyscale ultrasound is poor, because suspicious hypoechoic areas represent cancer in only 9–53% of cases [2-3]. Furthermore, up to 30% of prostate cancers are isoechoic [4-5]. Conventional prostate ultrasound has little advantage over digital rectal examination for detecting malignant areas. Consequently, new strategies for prostate cancer detection are required. Contrast-enhanced ultrasound (CEUS) is a real-time imaging technique with the capability of visualising perfusion patterns [6-8]. This imaging technology has revealed promising perspectives in the diagnosis of prostate cancer owing to its ability to improve the visualisation of tumour vascularity. Several studies have reported that CEUS-targeted biopsy detected more cancer than systematic biopsy by identifying the area with greatest enhancement of the prostate [9-12]. In a recent study reported by Tang et al [13], the haemodynamic parameters such as time to enhancement (AT), time to peak intensity (TTP) and peak intensity (PI) were compared between 44 prostate cancer lesions and 47 benign ones. However, the peak enhancement intensity was found to be the optimal discriminatory parameter. Based on these previous findings, the degree of enhancement of the tumour foci plays a significant role in cancer detection on CEUS imaging.Although CEUS detected more cases of cancer than baseline imaging, the cancer detection rate still remains far from satisfactory [14-15]. Halpern et al [14] compared areas of increased enhancement in the prostate at CEUS with pathological examination and found that only 8 of 31 cancer foci were detected at baseline greyscale imaging, and contrast-enhanced imaging allowed identification of 13 of the 31 cancers (42% sensitivity). In their research, more than half of all cancers failed to show an abnormal enhancement, which indicated that the prostate cancer foci were not always shown as marked enhancement. Mitterberger et al [11] stated that the cancer with increased enhancement found by means of targeted biopsy had a higher mean Gleason score than the ones found by random biopsies, which suggested that the Gleason score of the prostate cancer could influence the degree of enhancement of the tumour to a certain extent. However, to our knowledge, factors influencing the degree of enhancement of the tumour have not yet been systematically investigated. In the present study, we evaluated the peak intensity of prostate cancers during the administration of the ultrasound contrast agent, and aimed to identify factors that influenced the degree of enhancement of prostate cancer on CEUS imaging. We hypothesised that identifying factors influencing the tumour peak intensity value could be useful for differential diagnosis of benign and malignant lesions in the CEUS examination, which would allow for a more accurate determination of the target sites during the subsequent biopsy procedure.     

Diffusion-Weighted Imaging of a Prostate Cancer Xenograft Model Seen on a 7 Tesla Animal MR Scanner: Comparison of ADC Values and Pathologic Findings

Objective

To assess the relationship between apparent diffusion coefficient (ADC) values on diffusion-weighted magnetic resonance (MR) imaging and pathologic measures of a tumor using a prostate cancer xenograft model.

Materials and Methods

Eighteen athymic nude mice with 36 PC-3-induced tumors were sacrificed to obtain specimens immediately after MR imaging in order to compare the findings on MR images with those seen on pathological specimens. Using a high-field small-animal MR scanner, T1- and T2-weighted imaging and DW MR imaging was performed. Tumors were then processed for Hematoxylin and Eosin staining to evaluate tumor cellularity, intratumoral necrosis and immunostaining using antibodies directed against CD31 and vascular endothelial growth factor (VEGF) to determine the levels of microvessel density (MVD). Mean ADC values that were measured on the solid portion within each tumor were compared with tumor volume, cellularity, degree of necrosis, VEGF expression, and MVD in the corresponding section of the pathological specimen.

Results

Mean ADC values of the solid portion within the PC-3-induced high-grade tumors were significantly correlated with the degree of intratumoral necrosis (r = 0.63, p < 0.0001) and MVD (r = -0.44, p = 0.008) on pathologic slides. The ADC values were not significantly correlated with tumor cellularity, VEGF expression, or tumor volume in high-grade prostate cancer tissues.

Conclusion

In the xenografted prostate cancer model, the ADC values of the solid portion of the tumors are significantly correlated with tumor necrosis and MVD of the pathologic specimens. The ADC values may be utilized as surrogate markers for the noninvasive assessment of tumor necrosis and MVD in high-grade prostate cancer.     

Do apparent diffusion coefficient (ADC) values obtained using high b-values with a 3-T MRI correlate better than a transrectal ultrasound (TRUS)-guided biopsy with true Gleason scores obtained from radical prostatectomy specimens for patients with prostate cancer?

Objective

To investigate the usefulness of apparent diffusion coefficient (ADC) values in predicting true Gleason scores from radical prostatectomy specimen (tGS), compared with systematic transrectal ultrasound (TRUS)-guided biopsy GS (bGS).

Materials and methods

One hundred and five patients with biopsy-proven prostate cancer underwent preoperative DWI (b-values of 0, 1000, and 2000 s/mm²) of 3-T MRI. The mean and minimum ADCs of visible tumors were calculated for either of a pair of b-values: 0 and 1000 s/mm² (ADC₁₀₀₀), or 0 and 2000 s/mm² (ADC₂₀₀₀), and relationships between the four ADC parameters and tGS evaluated for the peripheral zone (PZ) and transition zone (TZ). For multiple tumors, the dominant tumor's GS and ADCs were estimated for cancer aggressiveness assessment by computing ROC curves.

Results

Significant negative correlations were observed between tGS and mean ADC₁₀₀₀, mean ADC₂₀₀₀, minimum ADC₁₀₀₀, and minimum ADC₂₀₀₀ (r = −0.41, −0.39, −0.39, and −0.37, respectively) of 100 visible PZ tumors and 66 visible TZ tumors (r = −0.40, −0.42, −0.29, and −0.21, respectively). For distinguishing high-grade from low/intermediate-grade PZ lesions, the areas under the curve (AUCs) of mean ADC₁₀₀₀ (0.751), mean ADC₂₀₀₀ (0.710), minimum ADC₁₀₀₀ (0.768), and minimum ADC₂₀₀₀ (0.752) were similar to that of the highest bGS (0.708) (p = 0.61, p = 0.98, p = 0.47, and p = 0.60, respectively). For distinguishing high-grade from low/intermediate-grade TZ lesions, AUCs of mean ADC₁₀₀₀ (0.779), and mean ADC₂₀₀₀ (0.811) were similar to that of the highest bGS (0.805) (p = 0.83 and p = 0.97).

Conclusion

Tumor ADCs obtained with high b-values could predict prostate cancer aggressiveness as effectively as systematic TRUS-guided biopsy.     

Diagnostic evaluation of magnetization transfer and diffusion kurtosis imaging for prostate cancer detection in a re-biopsy population

Objective

To evaluate diffusion kurtosis imaging (DKI) and magnetisation transfer imaging (MTI) compared to standard MRI for prostate cancer assessment in a re-biopsy population.

Methods

Thirty-patients were imaged at 3 T including DKI (K_app and D_app) with b-values 150/450/800/1150/1500 s/mm² and MTI performed with and without MT saturation. Patients underwent transperineal biopsy based on prospectively defined MRI targets. Receiver-operating characteristic (ROC) analyses assessed the parameters and Wilcoxon-signed ranked test assessed relationships between metrics.

Results

Twenty patients had ≥ 1 core positive for cancer in a total of 26 MRI targets (Gleason 3+3 in 8, 3+4 in 12, ≥ 4+3 in 6): 13 peripheral (PZ) and 13 transition zone (TZ). The apparent diffusion coefficient (ADC) and D_app were significantly lower and the K_app and MT ratio (MTR) significantly higher in tumour versus benign tissue (all p ≤ 0.005); ROC values 0.767-1.000. Normal TZ had: lower ADC and D_app and higher K_app and MTR compared to normal PZ. MTR showed a moderate correlation to K_app (r = 0.570) and D_app (r = -0.537) in normal tissue but a poor correlation in tumours. No parameter separated low-grade (Gleason 3+3) from high-grade (≥ 3+4) disease for either PZ (p = 0.414-0.825) or TZ (p = 0.148-0.825).

Conclusion

ADC, D_app, K_app and MTR all distinguished benign tissue from tumour, but none reliably differentiated low- from high-grade disease.

Key Points

? MTR was significantly higher in PZ and TZ tumours versus normal tissue ? K _app was significantly lower and D _app higher for PZ and TZ tumours ? There was no incremental value for DKI/MTI over mono-exponential ADC parameters ? No parameter could consistently differentiate low-grade (Gleason 3+3) from high-grade (≥ 3+4) disease ? Divergent MTR/DKI values in TZ tumours suggests they offer different functional information

     

Biexponential Apparent Diffusion Coefficients Values in the Prostate: Comparison among Normal Tissue,Prostate Cancer,Benign Prostatic Hyperplasia and Prostatitis

Objective

To investigate the biexponential apparent diffusion parameters of diverse prostate tissues and compare them with monoexponential apparent diffusion coefficient (ADC) value in the efficacy to discriminate prostate cancer from benign lesions.

Materials and Methods

Eleven healthy volunteers and 61 patients underwent a conventional (b-factors 0, 1000 s/mm²) and a 10 b-factor (0 to 3000 s/mm²) diffusion-weighted imaging (DWI). The monoexponential ADC value and biexponential parameters of fast ADC (ADCf), fraction of ADCf (f), slow ADC (ADCs) value for 29 prostate cancer, 28 benign prostatic hyperplasia (BPH), 24 prostatitis lesions and normal tissue were calculated and compared. Receiver operating characteristic analysis was performed to determine the sensitivity, specificity and optimal cut-off points.

Results

Prostate cancer had lower ADC, ADCf, f, and ADCs than all other tissues (p < 0.01). Prostatitis exhibited a lower ADC, ADCf, ADCs and f than the peripheral zone tissue (p < 0.01), and BPH showed a lower ADC and ADCf than the central gland tissue (p < 0.01). The ADCf demonstrated a comparable accuracy with ADC in differentiating cancer from BPH [area under the curve (AUC) 0.93 vs. 0.92] and prostatitis AUC 0.98 vs. 0.99) (both p > 0.05), but the AUC of f and ADCs in differentiating cancer from BPH (0.73 and 0.81) and prostatitis (0.88 and 0.91) were significantly lower than ADC (all p < 0.05).

Conclusion

The biexponential DWI appears to provide additional parameters for tissue characterization in prostate, and ADCf helps to yield comparable accuracy with ADC in differentiating cancer from benign lesions.     

Simulated required accuracy of image registration tools for targeting high-grade cancer components with prostate biopsies

Objectives

To estimate the required spatial alignment accuracy for correctly grading 95 % of peripheral zone (PZ) prostate cancers using a system for multiparametric magnetic resonance (MR)-guided ultrasound (US) biopsies.

Methods

PZ prostate tumours were retrospectively annotated on multiparametric MR series using prostatectomy specimens as reference standard. Tumours were grouped based on homogeneous and heterogeneous apparent diffusion coefficient (ADC) values using an automated ADC texture analysis method. The proportion of heterogeneous tumours containing a distinct, high Gleason grade tumour focus yielding low ADC values was determined. Both overall tumour and high-grade focal volumes were calculated. All high-grade target volumes were then used in a simulated US biopsy system with adjustable accuracy to determine the hit rate.

Results

An ADC-determined high-grade tumour focus was found in 63 % of the PZ prostate tumours. The focal volumes were significantly smaller than the total tumour volumes (median volume of 0.3 ml and 1.1 ml respectively). To correctly grade 95 % of the aggressive tumour components the target registration error (TRE) should be smaller than 1.9 mm.

Conclusions

To enable finding the high Gleason grade component in 95 % of PZ prostate tumours with MR-guided US biopsies, a technical registration accuracy of 1.9 mm is required.

Key Points

? MRI can identify foci of prostatic cancer with reduced apparent diffusion coefficients ? Sixty-three per cent of prostatic peripheral zone tumours contain high-grade tumour low ADC foci ? The median volume of such foci is 0.3 ml ? Biopsy targets are significantly smaller than whole tumour volumes ? Simulated registration accuracy is 1.9 mm for correctly grading 95 % of tumours     

Granulomatous Prostatitis After Intravesical Bacillus Calmette-Guérin Instillation Therapy: A Potential Cause of Incidental F-18 FDG Uptake in the Prostate Gland on F-18 FDG PET/CT in Patients with Bladder Cancer

Purpose

This study aimed to evaluate the possibility that Bacillus Calmette-Guérin (BCG)-induced granulomatous prostatitis can be a potential cause of benign F-18 FDG uptake.

Methods

A total of 395 bladder cancer patients who underwent F-18 FDG PET/CT (PET/CT) were retrospectively evaluated. Patients were divided into two groups according to BCG therapy status. Elapsed time after BCG therapy, serum PSA level, results of prostate biopsy, and the SUVmax and uptake pattern in the prostate gland were reviewed. For patients who underwent follow-up PET/CT, the changes in SUVmax were calculated.

Results

While 35 % of patients showed prostate uptake in the BCG therapy group, only 1 % showed prostate uptake in the non-BCG therapy group (p < 0.001). Among 49 patients with FDG-avid prostate lesions, none had suspected malignancy during the follow-up period (median: 16 months). Five patients revealed granulomatous prostatitis on biopsy. The incidence of FDG-avid prostate lesions was significantly higher if the elapsed time after BCG therapy was less than 1 year compared to more than 1 year (p < 0.001). Serum PSA was normal in 88 % of patients. All patients with incidental F-18 FDG uptake in the prostate gland showed focal or multifocal prostate uptake, and median SUVmax was 4.7. In 16 patients who underwent follow-up PET/CT, SUVmax was decreased in 14 patients (88 %) without treatment, and no patients demonstrated further increased prostate uptake (p < 0.001).

Conclusions

BCG-induced granulomatous prostatitis can be a potential cause of benign F-18 FDG uptake, especially in those with a history of bladder cancer treated with BCG. In BCG-induced granulomatous prostatitis, focal or multifocal prostate uptake is frequently seen within 1 year after BCG therapy, and the intensity of prostate uptake is decreased on the follow-up PET/CT without any treatment.     

Detection of prostate cancer with three-dimensional transrectal ultrasound: correlation with biopsy results

Objectives

The aim of this study was to evaluate the role of three-dimensional transrectal ultrasound in the diagnosis of prostate cancer.

Methods

A total of 112 patients with elevated serum prostate-specific antigen (PSA) or a positive digital rectal examination were evaluated using three-dimensional greyscale transrectal ultrasound (3D-GS TRUS) and three-dimensional power Doppler sonography (3D-PDS). Target biopsies were obtained together with 12 core systematic biopsies. Pathological results were correlated with the imaging data.

Results

Cancers were detected in 269 biopsy sites from 41 patients. 229 sites of cancer were depicted by 3D-GS TRUS and 213 sites were depicted by 3D-PDS. 30 sites were missed by both 3D-GS TRUS and 3D-PDS. Abnormal prostate images depicted by 3D-GS TRUS and 3D-PDS were associated with lesions with a Gleason score of 6.9 or higher.

Conclusion

The detection rates of prostate cancer were significantly improved with 3D-GS TRUS and 3D-PDS on serum PSA levels >10 ng ml^–1 or 20 ng ml^–1. 3D-GS TRUS and 3D-PDS may improve the biopsy yield by determining appropriate sites for target and systematic biopsies. The abnormalities detected by 3D ultrasound were associated with moderate- and high-grade prostate cancers. However, based on the number of false-negative TRUS results, the use of systematic prostate biopsies should not be eliminated.Prostate cancer is a common malignancy in older males. Previous autopsy studies have shown that one-third of males over 50 years old have latent cancer, yet only 10% develop clinically significant carcinomas during their lifetime [1]. The exact mechanism mediating the progression of microfocal cancers into symptomatic forms of the disease has not been elucidated. Since prostate cancers demonstrate remarkably heterogeneous behaviours ranging from slow-growing lesions to aggressive tumours that metastasise rapidly [2], the diagnosis and treatment of prostate cancers is very challenging. The current methods of screening for prostate cancer include measuring serum prostate-specific antigen (PSA) levels, digital rectal examination and transrectal ultrasound (TRUS) scanning and biopsy. However, controversy surrounds which screening method is the most clinically significant for detecting lesions.Since approximately 20–50% of prostate cancers are invisible by greyscale (GS) TRUS [3], GS TRUS has limited value for detection of prostate cancer [4,5]. In addition, 35% of lesions missed by GS TRUS are moderate- or high-grade tumours [6]. Colour Doppler ultrasound, as an important adjunct to GS TRUS, could improve detection of prostate cancer, although in one study 16% of cases with clinically significant cancer were still missed by this method [7].Three-dimensional (3D) TRUS is a relatively new imaging modality. Preliminary studies have shown improved cancer detection with 3D TRUS when compared with two-dimensional TRUS [8,9]. However, it is still unknown which malignant lesions may be detected by 3D TRUS. Furthermore, 3D TRUS has not been analysed in correlation with the site-specific biopsy pathological results.The purpose of this study was to assess the role of 3D-GS TRUS and 3D power Doppler sonography (3D-PDS) in the diagnosis of prostate carcinoma. This study correlated 3D-GS TRUS and 3D-PDS data with biopsy pathological results using a site-by-site analysis that included target and systematic biopsies.     

Perfusion MR Imaging in Gliomas: Comparison with Histologic Tumor Grade

Objective

To determine the usefulness of perfusion MR imaging in assessing the histologic grade of cerebral gliomas.

Materials and Methods

In order to determine relative cerebral blood volume (rCBV), 22 patients with pathologically proven gliomas (9 glioblastomas, 9 anaplastic gliomas and 4 low-grade gliomas) underwent dynamic contrast-enhanced T2*-weighted and conventional T1- and T2-weighted imaging. rCBV maps were obtained by fitting a gamma-variate function to the contrast material concentration versus time curve. rCBV ratios between tumor and normal white matter (maximum rCBV of tumor / rCBV of contralateral white matter) were calculated and compared between glioblastomas, anaplastic gliomas and low-grade gliomas.

Results

Mean rCBV ratios were 4.90°±1.01 for glioblastomas, 3.97°±0.56 for anaplastic gliomas and 1.75°±1.51 for low-grade gliomas, and were thus significantly different; p < .05 between glioblastomas and anaplastic gliomas, p < .05 between anaplastic gliomas and low-grade gliomas, p < .01 between glioblastomas and low-grade gliomas. The rCBV ratio cutoff value which permitted discrimination between high-grade (glioblastomas and anaplastic gliomas) and low-grade gliomas was 2.60, and the sensitivity and specificity of this value were 100% and 75%, respectively.

Conclusion

Perfusion MR imaging is a useful and reliable technique for estimating the histologic grade of gliomas.     

Prostate cancer vs. post‐biopsy hemorrhage: Diagnosis with T2‐ and diffusion‐weighted imaging

Purpose:

To assess the value of quantitative T2 signal intensity (SI) and apparent diffusion coefficient (ADC) to differentiate prostate cancer from post‐biopsy hemorrhage, using prostatectomy as the reference.

Materials and Methods:

Forty‐five men with prostate cancer underwent prostate magnetic resonance imaging (MRI), including axial T1‐weighted imaging (T1WI), T2WI, and single‐shot echo‐planar image (SS EPI) diffusion‐weighted imaging. Two observers measured, in consensus, normalized T2 signal intensity (SI) (nT2, relative to muscle T2 SI), ADC, and normalized ADC (nADC, relative to urine ADC) on peripheral zone (PZ) tumors, benign PZ hemorrhage, and non‐hemorrhagic benign PZ. Tumor maps from prostatectomy were used as the reference. Mixed model analysis of variance was performed to compare parameters among the three tissue classes, and Pearson's correlation coefficient was utilized to assess correlation between parameters and tumor size and Gleason score. Receiver‐operating characteristic (ROC)‐curve analysis was used to determine the performance of nT2, ADC, and nADC for diagnosis of prostate cancer.

Results:

nT2, ADC, and nADC were significantly lower in tumor compared with hemorrhagic and non‐hemorrhagic benign PZ (P < 0.0001). There was a weak but significant correlation between ADC and Gleason score (r = ?0.30, P = 0.0119), and between ADC and tumor size (r = ?0.40, P = 0.0027), whereas there was no correlation between nT2 and Gleason score and tumor size. The areas under the curve to distinguish tumor from benign hemorrhagic and non‐hemorrhagic PZ were 0.97, 0.96, and 0.933 for nT2, ADC, and nADC, respectively.

Conclusion:

Quantitative T2 SI and ADC/nADC values may be used to reliably distinguish prostate cancer from post‐biopsy hemorrhage. J. Magn. Reson. Imaging 2010;31:1387–1394. © 2010 Wiley‐Liss, Inc.

     

Multiparametric MRI of the prostate with three functional techniques in patients with PSA elevation before initial TRUS-guided biopsy

Objective:

Multiparametric MRI (mp-MRI) of the prostate is increasingly being used for local staging and detection of recurrence of prostate cancer (PCA). In patients with elevated prostate-specific antigen (PSA), mp-MRI could provide information on the position of the cancer, allowing adjustments to be made to the needle depth and direction before repeat transrectal ultrasound (TRUS)-guided biopsy to ensure accurate sampling of lesions. The purpose of the prospective study was to evaluate mp-MRI of the prostate in patients with PSA elevation before initial TRUS-guided biopsy.

Methods:

mp-MRI was performed in 94 patients using a 1.5-T scanner (MAGNETOM Aera^®; Siemens Healthcare, Erlangen, Germany) and 16-channel phased-array body coil (Siemens Healthcare). T₂ weighted images (T2WI), diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI and MR spectroscopy were obtained. TRUS-guided random biopsies and additional targeted biopsies of suspicious MRI areas were performed.

Results:

Additional targeted biopsies were obtained in 17 of 43 (40%) patients with PCA. 11 of 17 targeted biopsies contained PCA. 5 of 11 PCAs were diagnosed only by additional targeted biopsies. Sensitivity of mp-MRI in patients was 97.7% and specificity was 11.8%. mp-MRI was false negative in one patient. Sensitivity of mp-MRI in 207 lesions was 80.9% and specificity was 44.7%. In a logistic regression model, the apparent diffusion coefficient value was the only significant parameter to differentiate malignant and benign lesions.

Conclusion:

mp-MRI should be performed in patients with PSA elevation before initial TRUS-guided biopsy to allow additional targeted biopsies from suspicious areas of MRI. We recommend mp-MRI with T2WI, DWI, DCE MRI and MR spectroscopy. DWI as the most reliable technique should be used in every mp-MRI.

Advances in knowledge:

DWI is the most reliable technique in mp-MRI of the prostate.     

Natural history of small index lesions suspicious for prostate cancer on multiparametric MRI: recommendations for interval imaging follow-up

PURPOSE

We aimed to determine the natural history of small index lesions identified on multiparametric-magnetic resonance imaging (MP-MRI) of the prostate by evaluating lesion-specific pathology and growth on serial MP-MRI.

MATERIALS AND METHODS

We performed a retrospective review of 153 patients who underwent a minimum of two MP-MRI sessions, on an institutional review board-approved protocol. Index lesion is defined as the lesion(s) with the highest cancer suspicion score based on initial MP-MRI of a patient, irrespective of size. Two study cohorts were identified: (1) patients with no index lesion or index lesion(s) ≤7 mm and (2) a subset with no index lesion or index lesion(s) ≤5 mm. Pathological analysis of the index lesions was performed following magnetic resonance/ultrasound fusion-guided biopsy. Growth rate of the lesions was calculated based on MP-MRI follow-up.

RESULTS

Patients with small index lesions measuring ≤7 mm (n=42) or a subset with lesions ≤5 mm (n=20) demonstrated either benign findings (86.2% and 87.5%, respectively) or low grade Gleason 6 prostate cancer (13.8% and 12.5%, respectively) on lesion-specific targeted biopsies. These lesions demonstrated no significant change in size (P = 0.93 and P = 0.36) over a mean imaging period of 2.31±1.56 years and 2.40±1.77 years for ≤7 mm and ≤5 mm index lesion thresholds, respectively. These findings held true on subset analyses of patients who had a minimum of two-year interval follow-up with MP-MRI.

CONCLUSION

Small index lesions of the prostate are pathologically benign lesions or occasionally low-grade cancers. Slow growth rate of these small index lesions on serial MP-MRI suggests a surveillance interval of at least two years without significant change.Prostate cancer is the most common solid-organ malignancy in men in the western world, and it is one of the leading causes of cancer-related mortality (1). Widespread prostate specific antigen (PSA)-based screening has resulted in a marked increase in the rate of prostate cancer diagnosis, accompanied by significant downward grade and stage migration, as well as a decrease in mortality rate, though not commensurate with the detection rate (2, 3). Hence, there is a tendency to overtreat clinically-insignificant prostate cancer, leading to concerns regarding the quality of life. This has prompted renewed interest in more conservative management with active surveillance and investigational focal therapy options.Clinically-insignificant prostate cancer has been defined as small tumors with low Gleason grade, although thresholds for these parameters are not fully agreed upon (4–6). For instance, many reports use a lesion size threshold of 0.5 cm³, which corresponds to a spherical lesion with a diameter of approximately 1 cm (7). However, some investigators have used even smaller volume thresholds of 0.2 cm³ and 0.5 cm³ based on overall prostate cancer tumor burden on radical prostatectomy specimens with clinically-insignificant disease. Due to the formalin fixation and tissue contraction of the prostatectomy specimens, these lower volume thresholds would perhaps more accurately correspond to 5 mm and 7 mm diameter spherical lesions in the setting of prostates bearing two to three cancer foci, given the commonly multifocal nature of prostate cancer (8, 9).Multiparametric-magnetic resonance imaging (MP-MRI) of the prostate has been investigated as an anatomic and functional imaging method to aid in cancer detection (9–14). A subset of patients undergoing MP-MRI is found to have small index lesions, which would represent clinically-insignificant disease if found to harbor prostate cancer. In fact, when such lesions are biopsied they often prove to harbor benign tissue or low grade disease, and it would be tempting to use MP-MRI to monitor such patients. However, the optimal imaging interval has not been determined. Herein, we aim to define the natural history of small index lesions detected on MP-MRI, based on lesion-specific biopsy pathology and investigate subsequent growth rates determined by serial MRI studies.     

Prostate cancer: performance characteristics of combined T2W and DW-MRI scoring in the setting of template transperineal re-biopsy using MR-TRUS fusion

Objectives

To measure the performance characteristics of combined T₂-weighted (T₂W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) suspicion scoring prior to MR-transrectal ultrasound (TRUS) fusion template transperineal (TTP) re-biopsy.

Methods

Thirty-nine patients referred for prostate re-biopsy, with prior MRI examinations, were retrospectively included. The MR images, including T₂W and DW-MRI, had been independently evaluated prospectively by two radiologists using a structured scoring system. An MR-TRUS fusion TTP re-biopsy was used for MR target and non-targeted biopsy cores. Targeting performance and correlation with disease status were evaluated on a per-patient and per-region basis.

Results

The cancer yield was 41 % (16/39 patients). MR targeting accurately detected the disease in 12/16 (75 %) cancerous patients and missed the disease in 4/16 (25 %) patients, all with Gleason 3?+?3 disease. There was a significant relationship (P?<?0.01) between MR suspicion score and the significance of cancer. Reader 1 had significantly higher sensitivity in the transition zone (TZ; 0.84) compared with the peripheral zone (PZ; 0.32) (P?=?0.04). Inter-reader agreement was moderate for the PZ and substantial for the TZ.

Conclusions

MRI targeting is beneficial in the setting of TTP MR-TRUS fusion re-biopsy and MR suspicion score relates to prostate cancer clinical significance. A T₂W and DW-MRI structured scoring system results in good inter-reader agreement in this setting.

Key Points

? Pre-biopsy MRI aids the detection of high significance cancer during prostate re-biopsy. ? MRI suspicion level correlates with the clinical significance of prostate cancer detected. ? T ₂ W and DW-MRI structured scoring of pre-biopsy MRI permits good inter-reader agreement.     

Prediction of tumor differentiation using sequential PET/CT and MRI in patients with breast cancer

Objective

The aim of this study is to assess tumor differentiation using parameters from sequential positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) in patients with breast cancer.

Methods

This retrospective study included 78 patients with breast cancer. All patients underwent sequential PET/CT and MRI. For fluorodeoxyglucose (FDG)-PET image analysis, the maximum standardized uptake value (SUV_max) of FDG was assessed at both 1 and 2 h and metabolic tumor volume (MTV) and total lesion glycolysis (TLG). The kinetic analysis of dynamic contrast-enhanced MRI parameters was performed using dynamic enhancement curves. We assessed diffusion-weighted imaging (DWI)–MRI parameters regarding apparent diffusion coefficient (ADC) values. Histologic grades 1 and 2 were classified as low-grade, and grade 3 as high-grade tumor.

Results

Forty-five lesions of 78 patients were classified as histologic grade 3, while 26 and 7 lesions were grade 2 and grade 1, respectively. Patients with high-grade tumors showed significantly lower ADC-mean values than patients with low-grade tumors (0.99?±?0.19 vs.1.12?±?0.32, p?=?0.007). With respect to SUV_max1, MTV2.5, and TLG2.5, patients with high-grade tumors showed higher values than patients with low-grade tumors: SUV_max1 (7.92?±?4.5 vs.6.19?±?3.05, p?=?0.099), MTV2.5 (7.90?±?9.32 vs.4.38?±?5.10, p?=?0.095), and TLG2.5 (40.83?±?59.17 vs.19.66?±?26.08, p?=?0.082). However, other parameters did not reveal significant differences between low-grade and high-grade malignancies. In receiver-operating characteristic (ROC) curve analysis, ADC-mean values showed the highest area under the curve of 0.681 (95%CI 0.566–0.782) for assessing high-grade malignancy.

Conclusions

Lower ADC-mean values may predict the poor differentiation of breast cancer among diverse PET–MRI functional parameters.

     

Prospective Analysis on the Relation between Pain and Prostate Volume during Transrectal Prostate Biopsy

Objective

We wanted to assess the relationship between pain and the prostate volume during transrectal ultrasound (TRUS) guided biopsy.

Materials and Methods

Between July and September 2006, 71 patients scheduled for TRUS biopsy of the prostate were considered for inclusion to this study. These patients underwent periprostatic neurovascular bundle block with lidocaine prior to biopsy. Pain was assessed using a Visual Analogue Scale (VAS) during periprostatic neurovascular bundle block (VAS 1), during biopsy (VAS 2), and 20 minutes after biopsy (VAS 3). The mean pain scores were analyzed in the large prostate group (prostate volume > 40 cc) and the small prostate group (prostate volume ≤ 40 cc). P values < 0.05 were considered significant.

Results

The mean prostate volume was 42.2 cc (standard deviation: 8.6). The mean pain scores of VAS 1, 2 and 3 were 4.70 ± 1.61, 3.15 ± 2.44 and 1.05 ± 1.51, respectively. In the large prostate group, the mean pains scores of VAS 1, 2 and 3 were 4.75 ± 1.76, 3.51 ± 2.76 and 1.29 ± 1.70, respectively, whereas in the small prostate group, the means pain scores were 4.66 ± 1.46, 2.77 ± 2.0, and 0.80 ± 1.26, respectively. Although there were no statistical differences of VAS 1, the larger prostate group revealed higher pain scores of VAS 2 and 3 compared with the small prostate group (p < 0.05).

Conclusion

Patients with larger prostate volumes tend to feel more pain during and after TRUS guided prostate biopsy. Our findings suggest that additional analgesic strategies may be necessary when the patients with larger prostate undergo TRUS guided prostate biopsy.     

Application of Spatial Modulation of Magnetization to Cervical Spinal Stenosis for Evaluation of the Hydrodynamic Changes Occurring in Cerebrospinal Fluid

Objective

To evaluate the hydrodynamic changes occurring in cerebrospinal fluid (CSF) flow in cervical spinal stenosis using the spatial modulation of magnetization (SPAMM) technique.

Materials and Methods

Using the SPAMM technique, 44 patients with cervical spinal stenosis and ten healthy volunteers were investigated. The degree of cervical spinal stenosis was rated as low-, intermediate-, or high-grade. Low-grade stenosis was defined as involving no effacement of the subarachnoid space, intermediate-grade as involving effacement of this space, and high-grade as involving effacement of this space, together with compressive myelopathy. The patterns of SPAMM stripes and CSF velocity were evaluated and compared between each type of spinal stenosis and normal spine.

Results

Low-grade stenosis (n = 23) revealed displacement or discontinuity of stripes, while intermediate- (n = 10) and high-grade (n = 11) showed a continuous straight band at the stenotic segment. Among low-grade cases, 12 showed wave separation during the systolic phase. Peak systolic CSF velocity at C4-5 level in these cases was lower than in volunteers (p < .05), but jet-like CSF propulsion was maintained. Among intermediate-grade cases, peak systolic velocity at C1-2 level was lower than in the volunteer group, but the difference was not significant (p > .05). In high-grade stenosis, both diastolic and systolic velocities were significantly lower (p < .05).

Conclusion

Various hydrodynamic changes occurring in CSF flow in cervical spinal stenosis were demonstrated by the SPAMM technique, and this may be a useful method for evaluating CSF hydrodynamic change in cervical spinal stenosis.     

Breast Microcalcifications: Diagnostic Outcomes According to Image-Guided Biopsy Method

Objective

To evaluate the diagnostic outcomes of ultrasonography-guided core needle biopsy (US-CNB), US-guided vacuum-assisted biopsy (US-VAB), and stereotactic-guided vacuum-assisted biopsy (S-VAB) for diagnosing suspicious breast microcalcification.

Materials and Methods

We retrospectively reviewed 336 cases of suspicious breast microcalcification in patients who subsequently underwent image-guided biopsy. US-CNB was performed for US-visible microcalcifications associated with a mass (n = 28), US-VAB for US-visible microcalcifications without an associated mass (n = 59), and S-VAB for mammogram-only visible lesions (n = 249). Mammographic findings, biopsy failure rate, false-negative rate, and underestimation rate were analyzed. Histological diagnoses and the Breast Imaging Reporting and Data System (BI-RADS) categories were reported.

Results

Biopsy failure rates for US-CNB, US-VAB, and S-VAB were 7.1% (2/28), 0% (0/59), and 2.8% (7/249), respectively. Three false-negative cases were detected for US-CNB and two for S-VAB. The rates of biopsy-diagnosed ductal carcinoma in situ that were upgraded to invasive cancer at surgery were 41.7% (5/12), 12.9% (4/31), and 8.6% (3/35) for US-CNB, US-VAB, and S-VAB, respectively. Sonographically visible lesions were more likely to be malignant (66.2% [51/77] vs. 23.2% [46/198]; p < 0.001) or of higher BI-RADS category (61.0% [47/77] vs. 22.2% [44/198]; p < 0.001) than sonographically invisible lesions.

Conclusion

Ultrasonography-guided vacuum-assisted biopsy is more accurate than US-CNB when suspicious microcalcifications are detected on US. Calcifications with malignant pathology are significantly more visible on US than benign lesions.     

A direct comparison of contrast-enhanced ultrasound and dynamic contrast-enhanced magnetic resonance imaging for prostate cancer detection and prediction of aggressiveness

Introduction

Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) analyse tissue vascularization. We evaluated if CEUS can provide comparable information as DCE-MRI for the detection of prostate cancer (PCa) and prediction of its aggressiveness.

Material and methods

A post-hoc evaluation of 92 patients was performed. In each patient CEUS and DCE-MRI parameters of the most suspicious lesion identified on MRI were analysed. The predictive values for discrimination between benign lesions, low-/intermediate- and high-grade PCa were evaluated. Results of targeted biopsy served as reference standard (benign lesions, n=51; low- and intermediate-grade PCa [Gleason grade group 1 and 2], n=22; high-grade PCa [≥ Gleason grade group 3], n=19).

Results

In peripheral zone lesions of all tested CEUS parameters only time to peak (TTP_CEUS) showed significant differences between benign lesions and PCa (AUC 0.65). Of all tested DCE-MRI parameters, rate constant (K_ep) was the best discriminator of high-grade PCa in the whole prostate (AUC 0.83) and in peripheral zone lesions (AUC 0.89).

Conclusion

DCE-MRI showed a superior performance for detection of PCa and prediction of its aggressiveness. CEUS and DCE-MRI performed better in peripheral zone lesions than in transition zone lesions.

Key Points

? DCE-MRI gathers information about vascularization and capillary permeability characteristics of tissues. ? DCE-MRI can detect PCa and predict its aggressiveness. ? CEUS also gathers information about vascularization of tissues. ? For detection of PCa and prediction of aggressiveness DCE-MRI performed superiorly. ? Both imaging techniques performed better in peripheral zone lesions.

     

Incidental Focal 18F-FDG Uptake in the Prostate: Clinical Significance and Differential Diagnostic Criteria

Purpose

The extent and intensity of ¹⁸F-FDG uptake in prostate cancer patients are known to be variable, and the clinical significance of focal ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake that is incidentally found on positron emission tomography (PET) has not been established. We investigated the clinical significance of incidental focal prostate uptake of ¹⁸F-FDG on PET/computed tomography (CT) and analyzed differential findings on PET/CT between malignant and benign uptake.

Methods

A total of 14,854 whole-body ¹⁸F-FDG PET/CT scans (4,806 that were conducted during cancer screening and 10,048 that were conducted to evaluate suspected or alleged cancer outside of the prostate) were retrospectively reviewed to determine the presence, location, multiplicity and maximum standardized uptake value (SUVmax) of focal prostate uptake and combined calcification. The final diagnosis determined by serum prostate-specific antigen (PSA) level and biopsy was compared with PET findings.

Results

Incidental focal prostate uptake was observed in 148 of 14,854 scans (1.0 %). Sixty-seven of these 148 subjects who had diagnostic confirmation were selected for further analysis. Prostate cancer was diagnosed in nine of 67 subjects (13.4%). The remaining 58 subjects had no malignancy in the prostate based on normal serum PSA level (n = 53), or elevated serum PSA level with a negative biopsy result (n = 5). While 84.6% (11/13) of malignant uptake was peripherally located in the prostate glands, 60.2% (50/83) of benign uptake was centrally located (p < 0.05). The positive predictive value of peripheral focal uptake for malignancy was 25%. The SUVmax, multiplicity and combined calcification were not significantly different between the two groups.

Conclusion

Although incidental focal ¹⁸F-FDG uptake in the prostate is not common, the incidence of cancer with focal uptake is not low. Therefore, these findings deserve further evaluation. The location of the focal prostate uptake may help with the selection of high-risk prostate cancer patients.