Author (Yong-Ming Dai) from a commercial company, Siemens Healthcare, was a MR collaboration manager doing technique support in this study under Siemens collaboration regulation without any payment and personal concern regarding with this study. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.
Guarantor of integrity of the entire study: MYW YB DGD DPS. Study concepts: MYW YB DPS. Definition of intellectual content: MYW YB YHH DPS. Literature research: MYW YB YHH DGD JPD DPS YMD. Clinical studies: MYW YB YHH SWD QL YG WL DGD DPS. Statistical analysis: MYW YB DPS JT WQ. Manuscript editing: MYW YB DGD JPD DPS YMD JT WQ. Manuscript review: MYW YB YHH SWD QL YG WL DGD JPD DPS YMD. Conceived and designed the experiments: MYW YB YHH DGD DPS. Performed the experiments: YB YHH MYW SWD QL YG WL DGD. Analyzed the data: MYW YB YHH DGD DPS YMD JT WQ. Contributed reagents/materials/analysis tools: YB YHH SWD QL YG WL. Wrote the paper: YB MYW.
Susceptibility weighted imaging (SWI) is a new MRI technique which has been proved very useful in the diagnosis of brain diseases, but few study was performed on its value in prostatic diseases. The aim of the present study was to investigate the value of SWI in distinguishing prostate cancer from benign prostatic hyperplasia and detecting prostatic calcification.
23 patients with prostate cancer and 53 patients with benign prostatic hyperplasia proved by prostate biopsy were scanned on a 3.0T MR and a 16-row CT scanner. High-resolution SWI, conventional MRI and CT were performed on all patients. The MRI and CT findings, especially SWI, were analyzed and compared. The analyses revealed that 19 out of 23 patients with prostate cancer presented hemorrhage within tumor area on SWI. However, in 53 patients with benign prostatic hyperplasia, hemorrhage was detected only in 1 patient in prostate by SWI. When comparing SWI, conventional MRI and CT in detecting prostate cancer hemorrhage, out of the 19 patients with prostate cancer who had prostatic hemorrhage detected by SWI, the prostatic hemorrhage was detected in only 7 patients by using conventional MRI, and none was detected by CT. In addition, CT demonstrated calcifications in 22 patients which were all detected by SWI whereas only 3 were detected by conventional MRI. Compared to CT, SWI showed 100% in the diagnostic sensitivity, specificity, accuracy, positive predictive value(PPV) and negative predictive value(NPV) in detecting calcifications in prostate but conventional MRI demonstrated 13.6% in sensitivity, 100% in specificity, 75% in accuracy, 100% in PPV and 74% in NPV.
More apparent prostate hemorrhages were detected on SWI than on conventional MRI or CT. SWI may provide valuable information for the differential diagnosis between prostate cancer and prostatic hyperplasia. Filtered phase images can identify prostatic calcifications as well as CT.
Prostate cancer is the fifth most common cancer
Susceptibility weighted imaging (SWI) is a new MRI technology which reflects the magnetic susceptibility of tissue and is exquisitely sensitive to paramagnetic deoxygenated blood products such as deoxyhemoglobin, methemoglobin and haemosiderin
This study was approved by the hospital review boards of Henan Provincial People’s Hospital. Written informed consent was obtained from all patients. All research procedures were conducted in accordance with the Declaration of Helsinki.
This was a prospective study enrolling 76 patients with prostate diseases in Henan Provincial People's Hospital from June 2011 to September 2012. Transrectal ultrasonography (TRUS)-guided prostate biopsy proved 23 patients with prostate cancer (age range 55–91 years, average age 71 years) (
Case No./age (year) | SWI | Location of Pca |
1/79 | Hemorrhage | Central Zone |
2/78 | Hemorrhage | Peripheral Zone |
3/68 | Hemorrhage | Central Zone |
4/91 | Hemorrhage | Peripheral Zone |
5/78 | Hemorrhage | Peripheral Zone |
6/64 | Hemorrhage | Peripheral Zone |
7/55 | Hemorrhage | Central Zone |
8/72 | Hemorrhage | Peripheral Zone |
9/76 | Hemorrhage | Peripheral Zone |
10/79 | Hemorrhage | Peripheral Zone |
11/70 | Hemorrhage | Peripheral Zone |
12/71 | Hemorrhage | Peripheral Zone |
13/70 | Hemorrhage | Peripheral Zone |
14/56 | Hemorrhage | Peripheral Zone |
15/68 | Hemorrhage | Peripheral Zone |
16/73 | Negative | Peripheral Zone |
17/76 | Negative | Peripheral Zone |
18/71 | Negative | Peripheral Zone |
19/66 | Hemorrhage | Peripheral Zone |
20/72 | Hemorrhage | Peripheral Zone |
21/60 | Hemorrhage | Peripheral Zone |
22/71 | Negative | Central Zone |
23/69 | Hemorrhage | Peripheral Zone |
MRI was performed on a Siemens 3T scanner (Magnetom Trio, Siemens Medical Solutions, Erlangen, Germany) with a pelvic array phased coil (Siemens Medical System).
SWI is a three-dimensional fast low-angle gradient-echo (GRE) sequence. The imaging parameters of SWI for prostate are as follows: field of view (FOV) 300×300 mm2, matrix 282×512, TR (repetition time)/TE (echo time) = 22/12 milliseconds (ms), 20° flip angle, and 3 mm slice thickness. The acquisition time was 3 minutes and 36 seconds. The SWI images were created by using the magnitude and phase images
Conventional MRI was performed with a fast spin-echo (FSE) sequence. The imaging parameters were as follows:
Axial T1- weighted image (WI): field of view (FOV) 300×300 mm2, matrix 288×320, TR (repetition time)/TE (echo time) = 700/11 milliseconds (ms), 150° flip angle, and 3 mm slice thickness. The acquisition time was 3 minutes and 25 seconds.
Axial T2WI: FOV 300×300 mm2, matrix 272×320, TR/TE = 4000/87 ms, 140° flip angle, and 3 mm slice thickness. The acquisition time was 3 minutes and 54 seconds.
Sagittal T2WI: FOV 250×250 mm2, matrix 272×320, TR/TE = 4000/87 ms, 140° flip angle, and 3 mm slice thickness. The acquisition time was 3 minutes and 54 seconds.
Coronal T2WI: FOV 250×250 mm2, matrix 192×256, TR/TE = 4000/104 ms, 145° flip angle, and 4 mm slice thickness. The acquisition time was 2 minutes and 26 seconds.
CT was performed on a 16-row CT scanner (Brilliance 16, Philips Medical Systems). The imaging parameters are as follows: 120KV tube voltage, 250 mA tube current, and 3 mm thickness.
Each patient underwent transrectal ultrasound-guided sextant biopsies after completion of the MRI and CT examination within 10 days. The pathological results revealed that 23 patients had prostate cancer and 53 patients had benign prostatic hyperplasia.
Two radiologists with 11 and 15 years’ diagnostic experience, respectively, blinded to the histopathologic results analyzed all images. Tumorous and non-neoplastic areas were determined on the MR images in patients with prostate cancer. They observed the hemorrhagic foci and calcification in the prostate and discussed the final results when disaccordance appeared.
SPSS 17.0 statistical software was used to analyze data. Fisher's exact test was used to analyze the hemorrhagic manifestations on SWI between prostate cancer and benign prostatic hyperplasia group. A p value of less than 0.05 was considered significant. The sensitivity, specificity, accuracy, negative predictive values (NPV) and positive predictive values (PPV) at SWI and conventional MRI in detecting calcifications in prostate were evaluated using CT as the gold standard.
The tumor lesions of 19 patients with prostate cancer were located in the peripheral zone of the prostate, only 4 cases were within the central region. In 19 out of 23 patients (82.6%) with prostate cancer, hemorrhage was detected within the tumorous areas (16 patients with prostate cancer in the peripheral zone and 3 patients with tumor lesions in the central zone) by SWI (
Heterogeneous signal on conventional T1WI (A) and T2WI (B) (arrows) indicates tumor hemorrhage. No hemorrhage is demonstrated on CT (C). The tumor hemorrhage was also seen with SWI (D) and filtered phase image (E) (arrows). Histopathologic examination confirmed the diagnosis of prostate cancer (F).
No tumor hemorrhage is demonstrated on conventional T1WI (A), T2WI (B) and CT (C), but low signal within tumor on SWI (D) and filtered phase image (E) (arrows) indicates tumor hemorrhage. Histopathologic examination confirmed the diagnosis of prostate cancer (F).
Low signal on conventional T1WI (A) and T2WI (B) (arrows) indicates tumor hemorrhage. No hemorrhage is demonstrated on CT (C). The tumor hemorrhage was also seen with SWI (D) and filtered phase image (E) (arrows). The images in second row come from another slice of the same patient. No prostatic calcification is demonstrated on conventional T1WI (F) and T2WI (G), but dot-like high density on CT (H), low signal on SWI (I) and high signal on filtered phase image (J) (arrows) indicates calcificaiton.
The calcificatinos were detected in 22 patients by CT, including 5 out of 23 patients with prostate cancer and 17 out of 53 patients with benign prostatic hyperplasia.When MRIs were used, the calcifications were detected in all the 22 patients by SWI whereas in only 3 by routine MRI (
No prostatic calcification is demonstrated on conventional T1WI (A) and T2WI (B), but dot-like high density on CT (C), low signal on SWI (D) and high signal on filtered phase image (E) (arrows) indicates calcificaiton.
SWI is a new MRI technique which is more sensitive than CT, conventional MR and T2*WI GRE sequences in detecting paramagnetic blood products such as deoxyhemoglobin, methemoglobin and haemosiderin in central nervous system
As an advanced imaging technique, MRI has been gaining acceptance as an important tool in the evaluation of prostate diseases. T2WI is an important traditional sequence for the diagnosis of prostate cancer in the prostate peripheral zone but not specific. It is easy to distinguish the cancerous area which presents hypointense on T2WI from the uniform hyperintense background in the prostate peripheral zone. However, other changes such as prostatitis and fibrosis also can appear hypointense on T2WI
This study investigated the potential of SWI in distinguishing prostate cancer from benign prostatic hyperplasia. In 23 patients with prostate cancer, hemorrhage was detected in 19 patients within the tumorous areas by SWI (82.6%). However, small hemorrhage was detected only in 1 patient out of 53 (1.9%) patients with benign prostatic hyperplasia by SWI. The hemorrhage ratio within the lesions had significant difference between the two diseases. From this result, it seemed that prostate cancer may be more prone to bleeding than benign prostatic hyperplasia. The possible reason may be that the prostate cancer tissue has higher microvessel density (MVD) which was caused by increased vascular endothelial growth factor (VEGF) expression than normal prostate or benign prostatic hyperplasia tissue
Prostatic calcification is frequently encountered in urological practice. Some reports revealed that small, multiple calcifications are a normal, often incidental ultrasonographic finding in the prostate and represent a result of age rather than a pathologic entity. However, larger prostatic calcification may be related to underlying inflammation and require further evaluation and possible treatment
The major limitation of this study is that the histopathologic examination were all performed by biopsy instead of prostate resection. So the tumor hemorrhage on SWI was not directly proved by histopathologic examinations. In addition, the sample size in this study is not very large so we did not evaluate the incidence of tumor bleeding at different stages in patients with prostate cancer. Future studies may need to get more reliable results and investigate the potential of SWI in the prostate cancer staging.
In conclusion, our results indicate that SWI is more sensitive in the detection of prostate microbleeding and may be helpful in the differential diagnosis between prostatic cancer and benign prostatic hyperplasia. Filtered phase images can identify prostate calcifications as well as CT. More studies with larger sample size are needed to get more reliable results for clinical practice in the future.
We wish to thank Dr. E. Mark Haacke in deparment of Radiology in Wayne State University in USA for manuscript review.