| Backgroud:Prostate cancer is one of the common malignant tumors in endly men, it is the most common malignancy among men in the United States and the Europe. With the aging of our population, the improvement of people’s living standards, the application and progress of detection methods of proatate cancer, the incidence of prostate cancer in our country increases obviously and accounts for the third of male urinary and reproductive system cancer. The natural history of prostate cancer is long, the differences between the individual biological characteristics is large, the treatment and prognosis for prostate cancer depends on early diagnosis and preoperative staging.At present, the routine screening and early detection methods for prostate cancer include prostate-specific antigen(PSA),digital rectal examination(DRE), transrectal ultrasound(TRUS) guided biopsy and magnetic resonance imaging(MRI).PSA is a kind of glycoprotein with the activity of serine protease and is synthetized in prostate acinar and duct epithelium. Prostate cancer often leads to the increase of PSA, but PSA is not unique to prostate cancer. The prostate hyperplasia, prostatitis, fibrosis and biopsy can cause the increase of PSA. Especially, when PSA is between4.0～10.Ong/ml, which is called "grey diagnosis area", PSA is very difficult to differentiate prostate cancer and benign prostatic hyperplasia. In addition, if PSA is not high, prostate cancer may also not be ruled out. Therefore, the detection of PSA has its limitations, PSA is only a preliminary screening and can not be used as qualitative and quantitative diagnosis of prostate cancer.DRE is one of the routine methods for prostate cancer, this method is simple, non-invasive and low cost. Because70%of prostate cancer originates from peripheral zone of prostate, DRE has the important value for early diagnosis and staging of prostate cancer. However, DRE is too subjective, small lesions which locate in the central and peripheral zone are easy to be missed, and DRE is strongly related with experience of examiner. Thus, DRE is limited value on early stage and small volume of prostate cancer. Once prostate cancer is diagnosed by DRE, most of the patients are advanced, these patients miss the best time for treatment.TRUS guided prostate biopsy is considered as the gold standard for diagnosis of prostate cancer, but it is influenced with the number of needle and prostate volume, and there is certain rate of missed diagnosis. Moreover, biopsy is invasive and can cause bleeding and infection of prostate, hemospermia, hematuria and other complications.MRI has become the preferred method of non-invasive diagnosis of prostate cancer with the advantages of high resolution of soft tissue, multi-plane and multi-parameter imaging and non-ionizing radiation. For tumor diagnosis, the conventional T2-weighted imaging (T2WI) has been used for detecting and locating prostate cancer, where prostate cancer is hypointense relative to the normal peripheral tissue. However, hypointensity on T2WI is not specific for prostate cancer, benign prostatic hyperplasia, prostatitis, hemorrhage and fibrosis also cause hypointensities on T2WI, which decreases the diagnostic specificity of T2WI.Prostate cancer which locates in the central gland is difficult to be differentiated with normal tissue, especially with prostatic hyperplasia, because the signal of normal central gland is low, the signal of interstitial prostate hyperplasia is similar to that of prostate cancer. Moreover, some prostate tumors can be isointense or hyperintense on T2WI, which leads to low sensitivity of T2WI. In recent years, functional MR techniques such as dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), and magnetic resonance spectroscopy imaging (MRSI), have been used to increase the diagnostic accuracy of MR for prostate cancer.DCE-MRI is a useful imaging method for detecting the changes of tissue blood flow and is used to reflect blood supply and evaluate microcirculation state of tissue with time/intensity change. At present, the studies for DCE-MRI focused on semiquantitative method using signal intensity/time curve or more complicated quantitative approaches using quantitative parameters, such as Ktrans, Kep and Ve. However, the evaluation of signal intensity/time curves and quantitative parameters required specialized commercial software and was time consuming. Furthermore, these numerical values were not standardized. However, there are a few studies for raw DCE T1-weighted images (T1WI), but these studies were performed in the1.5T, the temporal resolution in these reports was low, the number of dynamic series was minimal, and the acquisition time after injection was too short for the sequence to show fully the hemodynamics of tumors. DWI is the only functional MR imaging method for the detection of in vivo tissue diffusion movement with short imaging time and without the injection of contrast agent. At present,there are a lot of researchs about the application of DWI in diagnosis of prostate cancer, but these studies focused on the diagnosis of quantitative ADC for prostate cancer, there are little reports about the diagnisis of DW images and ADC maps for prostate cancer. The measurement of ADC value is affected by b value, scanning, software and some physiological factors, which results in the ADC value that is difficult to be standardized. Compared with the measurement of ADC value, visual observation of DW images and ADC maps is more convenient and more simpler diagnosis method for prostate cancer. MRSI is a non-invasive method to detect vivo tissue metabolism and biochemical substances, it is also a kind of quantitative analysis method to make use of small change of chemical shift to collect information and expressing the concentratiom of some metabolites by spectral curves or numerical value. MRSI need endorectal coil, its process is complicated and time consuming, the patients of prostate cancer, especially those elderly patients, do not cooperate with poor tolerance. Moreover, MRSI easily fails because it is susceptible to interference from various factors, so MRSI is seldom used in cinical work. Because T2WI,DCE-MRI,DWI and MRSI have their limitations respectively in the diagnosis of prostate cancer, the combination of these methods reflect the morphology and function manifestations of prostate disease from different aspects and complement each other, which can further improve the accuracy of diagnosis of prostate cancer.Therefore, the research evaluates diagnostic value of T2WI,DCE-MRI,DWI and their combination on prostate cancer with3.0T and visual method. the contents are divided to three parts:(1) to explore the value of raw DCE Tl-weighted images on the diagnosis of prostate cancer, and to analyze the relationship between prostate cancer detection and Gleason score.(2) to explore and compare the value of DW images and ADC maps with different b values in the diagnosis of prostate cancer, and to analyze the relationship between prostate cancer detection with ADC maps and Gleason score.(3) to expore the value of combined T2WI,DWI and DCE-MRI for the diagnosis of prostate cancer.Part one:Application of3.0T DCE-MRI in the diagnosis of prostate cancerObjectiveTo explore the value of raw DCE T1-weighted images in the diagnosis of prostate cancer, and to analyze the relationship between prostate cancer detection and Gleason score.Materials and Methods1. Subjects85consecutive male patients with elevated PSA levels (>4.0ng/mL) and suspected prostate cancer, who had undergone both MPI and a subsequent transrectal prostate biopsy, were included in this study. All patients did not receive any treatment for prostate cancer prior to MRI and biopsy. The clincial manifestations are frequent urination, urgency, dysuria symptoms and so on. Forty-six patients were confirmed to have prostate adenocarcinomas upon histopathology. The Gleason scores of the46tumors in the study population were as follows:10patients scored<7(2patient scored4,3patients scored5, and5patients scored6),36patients scored≥7(20patients scored7,11patients scored8, and5patients scored9).2.MRI examinationAll MRI were performed on a3.0T whole-body multi-transmit scanner system (Achieva TX, Philips Healthcare, Best, The Netherlands) using a16-channel SENSE XL torso coil. DCE-MRI was performed using a three dimensional (3D) T1-fast field-echo (FFE) sequence in the axial plane, the scanning parameters were as follows:TR=5.5ms, TE=1.7ms, slice thickness=6.0mm, interslice gap=0mm, FOV=230mm x230mm, flip angle=15°, matrix size=256x256pixels. DCE-MRI images were scanned from the apex to the base of the prostate and a total of20slices were obtained. A20-slice volume was obtained every2-9s and imaging consisted of8precontrast volumes and96postcontrast volumes, the total time is5minutes and6seconds. Postcontrast imaging were initiated immediately after administering gadopentetate dimeglumine in the cephalic vein at a rate of2.5mL/s, and at a dose of0.1mmol/kg of body weight by the double tube injector (Medrad, American). Contrast agent injections were followed by a15mL saline flush.3.Image analysis and diagnostic criteriaTwo experienced radiologists in megnetic resonance diagnosis were blinded to the clinical data and prospectively analyzed the DCE-MRI together. Prostate lesions were diagnosed as cancer or non-cancer according to the location and signal features of lesions evaluated, and the results were compared with the pathological findings. On DCE-MRI images, compared to the background in the PZ and TZ, prostate lesions showing early and strong enhancement and rapid washout in the PZ and TZ were considered to be cancer; Prostate lesions showing early and strong enhancement and no obviously washout or slowly washout in the PZ and TZ were not considered to be cancer; Prostate lesions showing persistent enhancement were not considered to be cancer.4.Statistical AnalysisSPSS13.0software package was applied to deal with the data. Chi-square tests were used to correlate Gleason scores and prostate cancer detection. A p value<0.05was considered statistically significant.Results DCE-MRI was found to have a sensitivity of91.3%(42/46), a specificity of76.9%(30/39)%The Gleason scores of the46tumors in the study population were as follows:10patients scored<7,36patients scored≥7. The prostate cancer detection rate by DCE-MRI for tumors with Gleason scores>7was91.3%, but only70.0%for tumors with Gleason scores<7. The detection rates between the two score groupings were significantly different (x2=4.278, p-0.039).Conclusion1.3.0T DCE-MRI images can well show "an initial increase with an early washout" which has been described as typical hemodynamic characteristics of prostate cancers, and has a high value in the diagnosis of prostate cancer.2. The detection of prostate cancer with3.0T DCE-MRI was positively correlated with the Gleason score (p=0.039),that is to say, compared to the tumor with Gleason scores<7, the tumor with Gleason score≥7are more easy to be detected by DCE-MRI. Part two:Application of3.0T DWI in the diagnosis of prostate cancerObjectiveTo explore and compare the value of DW images and ADC maps with different b values in the diagnosis of prostate cancer, and to analyze the relationship between prostate cancer detection with ADC maps and Gleason score.Materials and Methods 1. Subjects62consecutive male patients with elevated PSA levels (>4.0ng/mL) and suspected prostate cancer, who had undergone both MRI and a subsequent transrectal prostate biopsy, were included in this study. All patients did not receive any treatment for prostate cancer prior to MRI and biopsy. The clincial manifestations are frequent urination, urgency, dysuria symptoms and so on. Thirty-five patients were confirmed to have prostate adenocarcinomas upon histopathology. The Gleason scores of the35tumors in the study population were as follows:7patients scored<7(1patient scored4,2patients scored5, and4patients scored6),28patients scored≥7(16patients scored7,8patients scored8, and2patients scored9).2.MRI examinationAll MRI were performed on a3.0T whole-body multi-transmit scanner system (Achieva TX, Philips Healthcare, Best, The Netherlands) using a16-channel SENSE XL torso coil. DWI was performed using a signle shot spin echo planar sequence in the axial plane. The scanning parameters at b values of0s/mm,500s/mm and1000s/mm2were as follows:TR=2000ms, TE=58ms, slice thickness=3.0mm, interslice gap=1.0mm, FOV=230mm×230mm, matrix size=256×256pixels. The data of DWI was sent to the MR3D workstation, and the ADC maps were automatically generated.3. Image analysis and diagnostic criteriaTwo experienced radiologists in magnetic resonance diagnosis were blinded to the clinical data and prospectively analyzed the DW images and ADC maps together. Prostate lesions were diagnosed as cancer or non-cancer according to the location and signal features of lesions evaluated, and the results were compared with the pathological findings. On DW images, compared to the background in the PZ and TZ, Prostate lesions that showed homogeneous high signal intensity area in the PZ and TZ were considered to be cancer; Prostate lesions that did not show homogeneous hign signal intensity area in the PZ or that showed isointensity, slightly high signal intensity or mixed signal intensity area in the TZ were considered to be noncancer; On ADC maps, prostate lesions that showed homogeneous low signal intensity area in the PZ and TZ were considered to be cancer, Prostate lesions did not show homogeneous low signal intensity area in the PZ or that showed isointensity, slightly low signal intensity or mixed signal intensity area in the TZ were considered to be noncancer;.4.Statistical AnalysisSPSS13.0software package was applied to deal with the data. The sensitivity and specificity of DW images and ADC maps for the diagnosis of prostate cancer were statistically compared using the McNemar test. Chi-square tests were used to correlate Gleason scores and prostate cancer detection by ADC maps. Ap value<0.05was considered statistically significant.ResultsWhen b=500s/mm2, DW images were found to have a sensitivity of54.3%(19/35), a specificity of70.4%(19/27). When b=1000s/mm2, DW images were found to have a sensitivity of80.0%(28/35), a specificity of77.8%(21/27). When b=1000s/mm2, ADC maps were found to have a sensitivity of88.6%(31/35), a specificity of85.2%(23/27).Compared b=500s/mm2with b=1000s/mm2,the study found that, when b=1000s/mm2,DW images had significantly higher sensitivity (McNemar test:p=0.012), although specificity was increased, the value was not significantly different (McNemar test:p=0.625). when b=1000s/mm, the sensitivity and specificity for ADC maps did not have significantly higher than DW images (McNemar test:p=0.453and/p=0.625) The Gleason scores of the35tumors in the study were as follows:7patients scored<7,28patients scored≥7. The prostate cancer detection rate by ADC maps for tumors with Gleason scores≥7was92.8%and71.4%for tumors with Gleason scores<7. The detection rates between the two score groups were not significantly different(x2=0.86,p=0.353).Conclusion1.When b=1000s/mm2, DW images and ADC maps have a high value on the diagnosis of prostate cancer, the sensitivity was greater with ADC maps compared to DW images, but the value was not significantly different (p=0.453); Compared b=500s/mm2with b=1000s/mm2, When b=500s/mm2, DW images had significantly lower sensitivity (p=0.012),that is to say, when b=500s/mm2,DW images has a low sensitivity on diagnosis of prostate cancer.2. when b=1000s/mm2,The detection rate of prostate cancer with ADC maps was not correlated with the Gleason score(p=0.353),that is to say, Gleason score of prostate cancer can not have effect on the detection rate of ADC maps for prostate cancer. Part three:Combined Application of3.0T MR T2WI,DWI and DCE-MRI in the diagnosis of prostate cancerObjectiveTo expore the value of combined T2WI,DWI and DCE-MRI in the diagnosis of prostate cancer.Materials and Methods 1.Subjects62consecutive male patients with elevated PSA levels (>4.0ng/mL) and suspected prostate cancer, who had undergone both MRI and a subsequent transrectal prostate biopsy, were included in this study. All patients did not receive any treatment for prostate cancer prior to MRI and biopsy. The clincial manifestations are frequent urination, urgency, dysuria symptoms and so on. Thirty-five patients were confirmed to have prostate adenocarcinomas upon histopathology. The Gleason scores of the35tumors in the study population were as follows:7patients scored<7(1patient scored4,2patients scored5, and4patients scored6),28patients scored>7(16patients scored7,8patients scored8, and2patients scored9).2.MRI examinationAll MRI were performed on a3.0T whole-body multi-transmit scanner system (Achieva TX, Philips Healthcare, Best, The Netherlands) using a16-channel SENSE XL torso coil. T2-weighed, turbo spin-echo images with spectrally selective attenuated inversion recovery were obtained in the axial and coronal planes, the scanning parameters were as follows:TR=1483ms, TE=70ms, slice thickness=5.0mm, interslice gap=1.0mm, number of slices=20, FOV=240mm x240mm, matrix size=256x256pixels. DWI was performed using a single shot spin echo planar sequence in the axial plane. The scanning parameters at b values of0s/mm2,500s/mm2and1000s/mm2were as follows:TR=2000ms, TE=58ms, slice thickness=3.0mm, interslice gap=1.0mm, FOV=230mm x230mm, matrix size=256x256pixels. The data of DWI was sent to the MR3D workstation, and the ADC maps were automatically generated. DCE-MRI was performed using a three dimensional (3D) Tl-fast field-echo (FFE) sequence in the axial plane, the scanning parameters were as follows:TR=5.5ms, TE=1.7ms, slice thickness=6.0mm, interslice gap=0mm, FOV=230×230mm, flip angle=15°matrix size=256× 256pixels. DCE-MRI images were scanned from the apex to the base of the prostate and a total of20slices were obtained. A20-slice volume was obtained every2.9s and imaging consisted of8precontrast volumes and96postcontrast volumes, the total time is5minutes and6seconds. Postcontrast imaging were initiated immediately after administering gadopentetate dimeglumine in the cephalic vein at a rate of2.5mL/s, and at a dose of0.1mmol/kg of body weight by the double tube injector(Medrad, American). Contrast agent injections were followed by a15mL saline flush.3. Image analysis and diagnostic criteriaTwo radiologists were blinded to the clinical data and prospectively analyzed the T2W images, ADC maps and DCE-MRI images together. Prostate lesions were diagnosed as cancer or non-cancer according to the location and signal features of lesions evaluated, and the results were compared with the pathological findings. On T2W images, prostate lesions that showed hypointense areas in the PZ or areas of homogeneous hypointensity with ill-defined margins and no visible capsule in the TZ were considered to be cancer,prostate lesions that did not show hypointense areas in the PZ or that showed isointensity, slightly high signal intensity, high signal intensity or mixed signal intensity area in the TZ were considered to be noncancer.. On ADC maps, prostate lesions that showed homogeneous low signal intensity area in the PZ and TZ were considered to be cancer, Prostate lesions did not show homogeneous low signal intensity area in the PZ or that showed isointensity, slightly low signal intensity or mixed signal intensity area in the TZ were considered to be noncancer. On DCE-MRI images, compared to the background in the PZ and TZ, prostate lesions showing early and strong enhancement and rapid washout in the PZ and TZ were considered to be cancer; Prostate lesions showing early and strong enhancement and no obviously washout or slowly washout in the PZ and TZ were not considered to be cancer; Prostate lesions showing persistent enhancement were not considered to be cancer.4.Statistical AnalysisSPSS13.0software package was applied to deal with the data. The sensitivity and specificity of T2WI,T2WI+ADC maps, T2WI+DCE-MRI and T2WI+ADC maps+DCE-MRI were statistically compared using the McNemar test. Ap value<0.05was considered statistically significant.ResultsT2WI was found to have a sensitivity of65.7%(23/35) and a specificity of63%(17/27). T2WI+ADC maps were found to have a sensitivity of88.6%(31/35) and a specificity of85.2%(23/27). T2WI+DCE-MRI were found to have a sensitivity of91.4%(32/35) and a specificity of81.5%(22/27).T2WI+ADC maps+DCE-MRI were found to have a sensitivity of91.4%(32/35) and a specificity of85.2%(23/27).All of these values increased using T2WI+ADC maps, T2WI+DCE-MRI and T2WI+DCE-MRI+ADC maps, T2WI+ADC maps, T2WI+DCE-MRI and T2WI+ADC maps+DCE-MRI had significantly higher sensitivity than T2WI(McNemar test:p=0.039,p=0.022and p=0.012), but the specificity were not significantly different (McNemar test:p=0.070,p=0.027and p=0.070).ConclusionCompared with T2WI, T2WI+ADC maps, T2WI+DCE-MRI and T2WI+ADC maps+DCE-MRI can significantly improve the sensitivity for the diagnosis of prostate cancer(p=0.039,p=0.022and p=0.012),but not significantly improve specificity for the diagnosis of prostate cancer (p=0.070,p=0.027and p=0.070). |
PDF Full Text Request