| BackgroundProstate cancer is the fifth most common cancer in the world; approximately onein six of males are supposed to be diagnosed with prostate cancer throughout theirlifetime.At present, the incidence of prostate cancer in China is much lower than thatin Europe and in the United States, but it is rising in recent years, because of ageingpopulation, unhealthy lifestyle, complications and so on.The majority of patients with prostate cancer are senior males. More than95%diagnosed patients are between the ages of45to89. The average age of patients is72and the peak age rangs from75to79. More than70%of the prostate cancer patientsare older than65years old. However, in recent years, the incidence of the prostatecancer patients who are younger than65years old is increasing continuously.The95%of prostate carcinoma is adenocarcinoma from the acinar cells. Thepredilection sites were the peripheral zone (75%), transitional zone (5%) and thecentral zone (20%). The85%of the adenocarcinomas were multicentric, which maybe the result of internal transferring. Histologic diagnosis of prostate cancer is basedon the two standards: the changes in organizational structure under the low powermicroscope and the cell mutation under the high power microscope.The Gleason scoring system has been accepted universiallyas a reference gradingsystem for dignosing prostate cancer. It has higher accuracy in evaluatingthe prognosis and curative effect of the patients, and has advantage of strongreproducibiltyandmorphological operation simple. The Gleason scoring systemtogether with with the gland differentiation degree and the growth of the tumor is inthe stroma is considered as the standard of classification and the evaluate degree ofmalignant tumor. It is mainly to observe the structural changes in the low, under amicroscope, but not to the individual tumor cell morphology of judgment. At the sametime, this scoring system is also used to observe the variation in different regionsof the tumor tissue structure.In clinic, some patients with prostate cancer have been discovered even aftertransurethral resection of the prostate or open operation. The specific symptoms ofearly prostate cancer are limited. Only when the tumor invades or obstructs theurethra and the bladder neck, the lower urinary irritation and obstruction symptomsappear. Even the emergence of acute lower urinary tract symptoms may happen, which lead to acute retention of urine, hematuria and urinary incontinence. Prostatecancer can metastasize to bones in patients with advanced tumors, usuallycomplicated with bone pain, pathologic fractures and other symptoms. In general, theearly clinical manifestation of prostate cancer is voiding dysfunction, like benignprostatic hyperplasia (BPH). The late clinical manifestations are some symptomscaused by the infiltration or distant metastasis of tumor.Due to the onset of the occult, the diagnosis of prostate cancer, especially theearly diagnosis is still a great challenge in clinic. Therefore, there are rationals toimprove the methods of prostate cancer diagnosis method.Currently in our clinical practice, the PSAtesting in combination with digitalrectal examination (DRE) and transrectal ultrasonography (TRUS) is used as an indexof early prostate cancer screening in the regular physical examination for the menwho are above50. If there is abnormal discovery, the transrectal prostate biopsyguided by ultrasound or magnetic resonance imaging (MRI) is performed in the nextstep. Pathological biopsy of prostate examination is the gold standard for thediagnosis of prostate cancer. But due to various reasons, the false negative rate of thischeck is still15%-34%. For some highly suspicious case without the pathologysupport, this issue is more prominent. In this case, MRI provides high resolution inthe three dimensional space and on soft tissue contrast and its multiple sequenceparameters of the imaging system.MRI is acknowledged as the current clinical best imaging diagnosis of prostatecancer. In recent years, as the basis of an established sequence, T2-weighted imaging(T2WI) has been widely used in the conventional morphological examination ofprostate. On T2WI images, in the normal prostate, the central zone and transitionalzone showed low signal intensity, and the peripheral zone showed obviously signalintensity. The typical sign of prostate cancer as a low signal defect in peripheralzone. However, the diagnosis of the peripheral zone prostate cancer would be affectedby the bleeding after biopsy, benign prostatic hyperplasia, prostatitis and so on. Morechallenges from the tumor diagnosis in the central zone and the transitional zone,because the signal intensity of tumor nodules in the region will overlap gland tissue.At the same time, developlent has been achived in a series of MR functionalimaging technology, such as the dynamic contrast enhanced MRI (DCE-MRI),diffusion weighted imaging (DWI) and magnetic resonance spectroscopy(MRS).These technologies further improve the accuracy of MRI diagnosis of prostate cancer. In recent years, the intravoxel incoherent motion MR imaging (IVIM-MRI) inthe diagnosis of prostate cancer has gained extensive attention. Based on DWI, it canget more accurate analysis in the condition of water molecules diffuse in the body.IVIM imaging technology has been developed more than20years in neurologicexamination and can be more comprehensive and accurate analysis of the voxelimaging area in the inland waters molecular diffusion real situation.At present, thereare a lot of clinical IVIM imaging analysis method. Classic double exponentialmodel is the most commonly method. DWI imaging scans can aquire larege numberof the data of water molecules diffuse with different b. IVIM-MRI technology takesthese data into a series of gaussian dispersion and non gaussian dispersion theoreticalformula calculation, and get the parameters as the diffusion coefficientD (slow D), the perfusion factorf and the pseudo diffusion coefficient D*(fastD). This study focuses on the analysis of the correlation between theIVIM-MRI parameters (D&f) and pathological, to evaluate its value of application onthe diagnosis of prostate cancer and the evaluation for malignant degree andprognosis.ObjectiveTo study the effect of intravoxel incoherent motion MR imaging diffusioncoefficients (D) and perfusion fractions (f)for prostate cancer detection and itsapplication on the diagnosis of prostate cancer and the evaluation for malignantdegree and prognosis.MethodsThe clinical and imaging data (T2WI, DWI, DCE-MRI and IVIM-MRI) of41patients with prostatic cancer were analyzed retrospectively, the significant point wasthe D and the f of the different pathological pattern and the different levels ofmalignancy.All measurements were shown as mean±standard deviation (SD). AStudent’spairedt-test with a two-tail distribution was used to evaluate the difference betweennormal and tumor tissues for each measure. The same method was used to evaluatethe difference between the different levels of malignancy. The statistical significancewas considered at P<0.05.Results1. The DWI and IVIM-MRI parameters:ADC value(1.616±0.391vs0.775± 0.309×10-3mm2/s) and D (1.323±0.312vs0.547±0.341×10-3mm2/s) showed thesignificant difference (p<0.05), between the benign hyperplastic tissue and the tumortissue.At the same time, the study of f was more interesting. We found that, when thedata include b=800s/mm2, between benign hyperplasia and tumor tissue, f (43.359±37.983vs33.492±23.079%) did not have significant difference (p>0.05). Only aftereliminate the data with the b=800s/mm2, the f of benign hyperplasia and tumortissue (5.837±3.679vs10.983±7.814%) would showe the statistically significantdifferences (p<0.05).2. The DCE-MRI and IVIM-MRI parameters: Ktrans(0.296±0.121vs0.526±0.213min-1), Ve (29.631±13.472vs41.569±12.334%) and Vp (4.737±2.958vs8.397±6.648%), as same as D, f(excluding the b=800s/mm2), showed the significantdifference (p<0.05), between the benign hyperplastic tissue and the tumor tissue.And, there was a weak positive correlation between f and Ktrans, Vp.3. Between the high risk group and low risk group, only D (0.513±0.183vs0.735±0.251×10-3mm2/s) asADC (0.623±0.142vs0.947±0.103×10-3mm2/s) showed significant differences (p<0.05), between the two groups.The parameters of perfusion of tissue: Ktrans(0.562±0.032vs0.507±0.113min-1),Ve (39.872±13.637vs37.981±12.739%) and Vp (9.033±7.218vs8.395±6.721%)between the two groups showed no differences (p>0.05).Also worth mentioning is,whether it contains or eliminating b=800s/mm2, f (including b=800s/mm2data:26.946±15.152vs37.425±19.023%; excluding b=800s/mm2data:3.753±3.788vs6.782±6.351%) did not show any statistically significant difference (p>0.05).ConclusionsIVIM-MRI is a promising techinique in the differential diagnosis of prostaticcancer. It is undeniable that accurate quantification of the D value would eventuallytranslate into more reliable diagnosis on tumor malignancy, which would havesignificant clinical relevance with better patient managements. |
PDF Full Text Request