Phased-array Magnetic Resonance Imaging Research Articles

A New Phased-Array Magnetic Resonance Imaging Receive-Only Coil for HBO2 Studies.

The paper describes a new magnetic resonance imaging (MRI) phased-array receive-only (Rx) coil for studying decompression sickness and disorders of hyperbaricity, including nitrogen narcosis. Functional magnetic resonance imaging (fMRI) is noninvasive, is considered safe, and may allow studying the brain under hyperbaric conditions. All of the risks associated with simultaneous MRI and HBO2 therapy are described in detail, along with all of the mitigation strategies and regulatory testing. One of the most significant risks for this type of study is a fire in the hyperbaric chamber caused by the sparking of the MRI coils as a result of high-voltage RF arcs. RF pulses at 128 MHz elicit signals from human tissues, and RF sparking occurs commonly and is considered safe in normobaric conditions. We describe how we built a coil for HBO2-MRI studies by modifying an eight-channel phased-array MRI coil with all of the mitigation strategies discussed. The coil was fabricated and tested with a unique testing platform that simulated the worst-case RF field of a three-Tesla MRI in a Hyperlite hyperbaric chamber at 3 atm pressure. The coil was also tested in normobaric conditions for image quality in a 3 T scanner in volunteers and SNR measurement in phantoms. Further studies are necessary to characterize the coil safety in HBO2/MRI.

3T external phased-array magnetic resonance imaging in detection of obstetric anal sphincter lesions: a pilot study.

Three-dimensional endoanal ultrasound (3D EAUS) has been the gold standard for detecting anal sphincter lesions in patients with a history of obstetric anal sphincter injury (OASI). Advances in imaging technologies have facilitated the detection of these lesions with external phased-array magnetic resonance imaging (MRI), which could offer an alternative imaging modality for the diagnosis of residual OASI (ROASI) in centers where 3D EAUS imaging is not available. To compare two diagnostic modalities: the 3D EAUS and 3T external phased-array MRI in the detection of residual anal sphincter lesions. A total of 24 women with a history of OASI were imaged with both 3D EAUS and 3T external phased-array MRI after primary repair of the injury. Intraclass correlation (ICC) and interrater reliability (IRR) values were calculated for the grade and circumference of the sphincter lesion. Sphincter lesions were graded according to the Sultan classification. There was an almost perfect agreement between 3D EAUS and 3T external phased-array MRI in determining the extent of the sphincter lesions according to the Sultan classification (κ = 0.881; P < 0.001) and the circumference of the external anal sphincter defects, measured in degrees (κ = 0.896; P < 0.001). The results of this study indicate that 3T external phased-array MRI and 3D EAUS yield comparable results in the diagnosis of ROASI. These findings suggest that 3T external phased-array MRI could serve as an alternative diagnostic modality to 3D EAUS in the diagnosis of ROASI.

The role of magnetic resonance imaging and magnetic resonance diffusion weighted image in preoperative staging of rectal cancer in comparison to postoperative histopathology

Background: With outstanding soft tissue contrast, functional imaging capabilities, and multiplanar capacity, high-resolution phased-array magnetic resonance imaging MRI is considered as a basic imaging modality for preoperative local staging of rectal cancer. And so MRI fills a void in clinical practice by allowing for precise local staging of rectal cancer prior to treatment decisions. The diffusion-weighted image used as enhancing utility for MRI in patients with rectal cancer. Objectives: The aim of work was to assess the role of MRI imaging including the (diffusion weighted imaging DWI and Apparent diffusion coefficient ADC map) in preoperative rectal cancer staging, in comparison to post-operative histopathology. Patients and methods: A total of 50 patients were included in the study, presented to South Valley University hospital and underwent MRI examination in MRI unit at South Valley University hospital. Results: Regarding the circumferential resection margin (CRM) infiltration, MRI diagnosed CRM involvement in 15 cases while rest 35 cases showing free CRM. From these positive cases only 13 were truly positive with histopathology, other two cases proved to be positive with histopathology not diagnosed by MRI. MRI showed MRF infiltration in only 18 cases. Histopathological assessment showed that MRF infiltration in only 15 cases and the rest 35 cases showing free MRF (agreement 83.3%). Conclusion: The results of this study demonstrate that preoperative MRI has a great value in achieving the best treatment strategy through accurate staging of rectal cancer, prediction of negative CRMs and involvement of the perirectal and pelvic LNs.

Comparison of 3D endoanal ultrasound and external phased array magnetic resonance imaging in the diagnosis of obstetric anal sphincter injuries

ObjectivesThe gold standard of postpartum anal sphincter imaging has been the 3D endoanal ultrasound (EAUS). Development of magnetic resonance imaging (MRI) has allowed anal sphincter evaluation without the use of endoanal coils. The aim of this study is to compare these two modalities in diagnosing residual sphincter lesions post obstetric anal sphincter injury (OASI).MethodsForty women were followed up after primary repair of OASI with both 3D EAUS and external phased array MRI. Details of the anal sphincter injury and sphincter musculature were gathered and analysed.ResultsThere was a moderate interrater reliability (κ = 0.510) between the two imaging modalities in detecting sphincter lesions, with more lesions detected by MRI. There was a moderate intraclass correlation (ICC) between the circumference of the tear (κ = 0.506) and a fair ICC between the external anal sphincter thickness measurements at locations 3 and 9 on the proctologic clock face (κ = 0.320) and (κ = 0.336).ConclusionsThe results of our study indicate that the use of external phased array MRI is feasible for detecting obstetric anal sphincter lesions postpartum. This allows for imaging of the sphincter defects in centres where EAUS imaging is not available.Key Points• A two centre prospective study that showed external phased array MRI to be a valid imaging modality for diagnosing obstetric anal sphincter injuries.

MP17-14 UTILITY OF PREOPERATIVE 3 TESLA MULTIPARAMETRIC PELVIC PHASED-ARRAY MAGNETIC RESONANCE IMAGING IN PREDICTION OF EXTRACAPSULAR EXTENSION OF PROSTATE CANCER AND ITS IMPACT ON SURGICAL MARGIN STATUS: EXPERIENCE AT A CANADIAN TERTIARY ACADEMIC HEALTH CENTER

You have accessJournal of UrologyImaging/Radiology: Uroradiology III1 Apr 2015MP17-14 UTILITY OF PREOPERATIVE 3 TESLA MULTIPARAMETRIC PELVIC PHASED-ARRAY MAGNETIC RESONANCE IMAGING IN PREDICTION OF EXTRACAPSULAR EXTENSION OF PROSTATE CANCER AND ITS IMPACT ON SURGICAL MARGIN STATUS: EXPERIENCE AT A CANADIAN TERTIARY ACADEMIC HEALTH CENTER Jen Hoogenes, Ian Wright, Colm Boylan, and Bobby Shayegan Jen HoogenesJen Hoogenes More articles by this author , Ian WrightIan Wright More articles by this author , Colm BoylanColm Boylan More articles by this author , and Bobby ShayeganBobby Shayegan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.856AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Magnetic resonance imaging (MRI) is rapidly gaining ground in the preoperative planning for radical prostatectomy (RP). Reports of its predictive ability to detect extracapsular extension (ECE) have varied significantly in the literature. We evaluated the ability of 3 Tesla (3T) pelvic phased-array (PPA) multiparametric MRI (mpMRI) to predict ECE and its subsequent effect on surgical margin status in a patient cohort treated by a single urologic oncologist. METHODS We retrospectively evaluated 48 preoperative RP patients who underwent 3T PPA mpMRI based on clinical probability of adverse pathological features. T1- and T2-weighted sequences, diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) mpMRI was used in all cases, each read by an expert genitourinary radiologist. Tumor stage based on mpMRI was compared to pathological stage. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of mpMRI in predicting ECE were calculated. Positive surgical margin rates of patients with positive ECE on mpMRI were compared to those patients with negative ECE on mpMRI. RESULTS Forty-two (88%) patients were intermediate or high risk based on D'Amico criteria. The mpMRI reports predicted 19 (40%) patients to be positive for ECE, while final pathology revealed that nine of these patients were actually ECE positive, with two having positive surgical margins. Of the 29 (60%) patients who were not predicted to have ECE based on mpMRI, 14 had positive ECE on pathology, 12 of whom had positive surgical margins. Preoperative 3T PPA mpMRI using T1- and T2-weighted sequences with DWI and DCE achieved a sensitivity of only 44% and a specificity of 61% in predicting ECE on surgical pathology. The PPV and NPV were 55% and 50%, respectively. Of the patients with ECE reported on mpMRI, 11% had positive surgical margins compared to 41% of those patients without ECE on mpMRI. CONCLUSIONS At our center, the use of preoperative 3T PPA mpMRI using T1- and T2-weighted sequences with DWI and DCE in predicting pathological ECE and surgical margin status is of questionable benefit. Our findings suggest that preoperative mpMRI reports of organ-confined disease may result in closer surgical dissection and subsequent positive surgical margins, regardless of true pathological staging. As such, caution should be exercised when basing intraoperative decisions on mpMRI findings. © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e181 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jen Hoogenes More articles by this author Ian Wright More articles by this author Colm Boylan More articles by this author Bobby Shayegan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

MRI in local staging of rectal cancer: an update

Preoperative imaging for staging of rectal cancer has become an important aspect of current approach to rectal cancer management, because it helps to select suitable patients for neoadjuvant chemoradiotherapy and determine the appropriate surgical technique. Imaging modalities such as endoscopic ultrasonography, computed tomography, and magnetic resonance imaging (MRI) play an important role in assessing the depth of tumor penetration, lymph node involvement, mesorectal fascia and anal sphincter invasion, and presence of distant metastatic diseases. Currently, there is no consensus on a preferred imaging technique for preoperative staging of rectal cancer. However, high-resolution phased-array MRI is recommended as a standard imaging modality for preoperative local staging of rectal cancer, with excellent soft tissue contrast, multiplanar capability, and absence of ionizing radiation. This review will mainly focus on the role of MRI in preoperative local staging of rectal cancer and discuss recent advancements in MRI technique such as diffusion-weighted imaging and dynamic contrast-enhanced MRI.

954 Utility of preoperative 3 Tesla pelvic phased-array magnetic resonance imaging in prediction of extracapsular extension of prostate cancer and its impact on surgical margin status: Experience at a Canadian tertiary academic health science center

954 Utility of preoperative 3 Tesla pelvic phased-array magnetic resonance imaging in prediction of extracapsular extension of prostate cancer and its impact on surgical margin status: Experience at a Canadian tertiary academic health science center

Prostate MRI: Who, when, and how? Report from a UK consensus meeting

The current pathway for men suspected of having prostate cancer [transrectal biopsy, followed in some cases by magnetic resonance imaging (MRI) for staging] results in over-diagnosis of insignificant tumours, and systematically misses disease in the anterior prostate. Multiparametric MRI has the potential to change this pathway, and if performed before biopsy, might enable the exclusion of significant disease in some men without biopsy, targeted biopsy in others, and improvements in the performance of active surveillance. For the potential benefits to be realized, the setting of standards is vital. This article summarizes the outcome of a meeting of UK radiologists, at which a consensus was achieved on (1) the indications for MRI, (2) the conduct of the scan, (3) a method and template for reporting, and (4) minimum standards for radiologists.

MRI and CT of anal carcinoma: a pictorial review

BackgroundSquamocellular anal carcinoma is increasingly diagnosed in patients with risk factors.MethodsState-of-the-art imaging with magnetic resonance imaging (MRI) using phased-array coils and volumetric multidetector computed tomography (CT) provides detailed visualisation of anal disorders, identification and extent assessment of neoplastic tissue, detection and characterisation of nodal and visceral metastases. MRI has been recommended by the European Society for Medical Oncology (ESMO) as the preferred modality of choice to stage anal cancer, taking into account the maximum tumour diameter, invasion of adjacent structures and regional lymph node involvement.ResultsCross-sectional imaging techniques allow the identification of coexisting complications, and differentiation from other perineal abnormalities.ConclusionCross-sectional imaging is useful for planning radiotherapy, surgical drainage or salvage abdomino-perineal resection. After chemo-radiotherapy, MRI follow-up provides confident reassessment of therapeutic response, persistent or recurrent disease.Teaching Points • Anal carcinoma is increasingly diagnosed in patients with human immunodeficiency virus (HIV), anoreceptive intercourse, chronic inflammatory bowel disease. • An established association exists with human papillomavirus (HPV) infection and premalignant intra-epithelial dysplasia. • Phased-array MRI is recommended as the preferred imaging modality for regional staging. • Imaging allows detection of infectious complications, planning of radiotherapy or salvage surgery. • Follow-up MRI allows reliable assessment of therapeutic response after chemo-radiotherapy.

3-Dimensional Elastic Registration System of Prostate Biopsy Location by Real-Time 3-Dimensional Transrectal Ultrasound Guidance With Magnetic Resonance/Transrectal Ultrasound Image Fusion

We determined the accuracy of the novel Urostation 3-dimensional transrectal ultrasound system (Koelis, La Tranche, France) for image based mapping biopsies in a prostate phantom. The system is capable of 1) registering the 3-dimensional location of each biopsy track in the 3-dimensional prostate volume data and 2) performing elastic image fusion of transrectal ultrasound with magnetic resonance imaging. We used 3 CIRS-053 prostate phantoms containing 3 hypoechoic lesions to perform ultrasound guided biopsy and 3 CIRS-066 phantoms (Computerized Imaging Reference Systems, Norfolk, Virginia) containing 3 isoechoic but magnetic resonance imaging visible lesions to perform magnetic resonance fusion guided biopsy. Three targeted biopsies were done per lesion. Each biopsy tract was injected with gadolinium based magnetic resonance contrast mixed with india ink. Phantoms were then subjected to 1 mm slice magnetic resonance imaging and serial step sectioning to assess the accuracy of targeted biopsy. A total of 27 ultrasound guided biopsies were targeted into 9 hypoechoic lesions. All 27 biopsies (100%) successfully hit the target lesion. For hypoechoic lesions mean ± SD procedural targeting error was 1.52 ± 0.78 mm and system registration error was 0.83 mm, resulting in an overall error of 2.35 mm. Of the 27 magnetic resonance fusion biopsies 24 (84%) hit the lesion. For isoechoic lesions mean procedural targeting error was 2.09 ± 1.28 mm, resulting in an overall error of 2.92 mm. The novel, computer assisted, 3-dimensional transrectal ultrasound biopsy localization system achieved encouraging accuracy with less than 3 mm error for targeting hypoechoic and isoechoic lesions. The ability to register actual biopsy trajectory and perform elastic magnetic resonance/ultrasound image fusion is a significant advantage for future focal therapy application.

Diagnostic Accuracy of MRI for Assessment of T Category, Lymph Node Metastases, and Circumferential Resection Margin Involvement in Patients with Rectal Cancer: A Systematic Review and Meta-analysis

Magnetic resonance imaging (MRI) is increasingly being used for rectal cancer staging. The purpose of this study was to determine the accuracy of phased array MRI for T category (T1-2 vs. T3-4), lymph node metastases, and circumferential resection margin (CRM) involvement in primary rectal cancer. Medline, Embase, and Cochrane databases were searched using combinations of keywords relating to rectal cancer and MRI. Reference lists of included articles were also searched by hand. Inclusion criteria were: (1) original article published January 2000-March 2011, (2) use of phased array coil MRI, (3) histopathology used as reference standard, and (4) raw data available to create 2×2 contingency tables. Patients who underwent preoperative long-course radiotherapy or chemoradiotherapy were excluded. Two reviewers independently extracted data. Sensitivity, specificity, and diagnostic odds ratio were estimated for each outcome using hierarchical summary receiver-operating characteristics and bivariate random effects modeling. Twenty-one studies were included in the analysis. There was notable heterogeneity among studies. MRI specificity was significantly higher for CRM involvement [94%, 95% confidence interval (CI) 88-97] than for T category (75%, 95% CI 68-80) and lymph nodes (71%, 95% CI 59-81). There was no significant difference in sensitivity between the three elements as a result of wide overlapping CIs. Diagnostic odds ratio was significantly higher for CRM (56.1, 95% CI 15.3-205.8) than for lymph nodes (8.3, 95% CI 4.6-14.7) but did not differ significantly from T category (20.4, 95% CI 11.1-37.3). MRI has good accuracy for both CRM and T category and should be considered for preoperative rectal cancer staging. In contrast, lymph node assessment is poor on MRI.

Role of pelvic phased array magnetic resonance imaging in staging of prostate cancer specifically in patients diagnosed with clinically locally advanced tumours by digital rectal examination

To assess the value of dynamic contrast-enhanced magnetic resonance imaging (MRI) for the prediction of extracapsular extension (ECE) in patients with clinical T3 (cT3) prostate cancer (PCa) compared to digital rectal examination (DRE). A retrospective review of data for patients treated by radical prostatectomy for cT3 PCa was performed. Patients who underwent MRI in the pre-operative work-up were included. The likelihoods of extracapsular extension (T3a) and seminal vesicle invasion (T3b) were scored on the basis of MR images. For data analysis, receiver operating characteristic (ROC) curves were generated. Overall, 70 consecutive patients were included. Mean age was 63.8 (range 45-75) years, and the mean PSA level was 11.3 (range 2.9-26) ng/ml. Pathological analysis of the prostatic specimens confirmed 81.4% (n = 57) had pT3 disease. According to MRI, 57 (81.4%) patients were predicted correctly to have T3 disease. The overstaging (actual pT2) by either DRE or MRI or both was 18.6, 7 or 7%, respectively. The sensitivity, specificity and positive (PPV) and negative predictive values (NPV) of MRI were 94.7, 69, 93 and 75%. The kappa index of concordance between pre-operative MRI stage and pathological stage was 0.68 (P < 0.00001). The performance of MRI for T3 staging was AUC 0.87 (95% CI, 0.77-0.97). Pre-prostatectomy MRI adds significant incremental value to the assessment of patients with cT3 disease. Its ability to accurately predict and characterize pathological T3 status and its superiority to standard clinical variables (e.g. DRE) confirm its usefulness in pre-operative work-up.

Multiparametric 3T Prostate Magnetic Resonance Imaging to Detect Cancer: Histopathological Correlation Using Prostatectomy Specimens Processed in Customized Magnetic Resonance Imaging Based Molds

We determined the prostate cancer detection rate of multiparametric magnetic resonance imaging at 3T. Precise one-to-one histopathological correlation with magnetic resonance imaging was possible using prostate magnetic resonance imaging based custom printed specimen molds after radical prostatectomy. This institutional review board approved prospective study included 45 patients (mean age 60.2 years, range 49 to 75) with a mean prostate specific antigen of 6.37 ng/ml (range 2.3 to 23.7) who had biopsy proven prostate cancer (mean Gleason score of 6.7, range 6 to 9). Before prostatectomy all patients underwent prostate magnetic resonance imaging using endorectal and surface coils on a 3T scanner, which included triplane T2-weighted magnetic resonance imaging, apparent diffusion coefficient maps of diffusion weighted magnetic resonance imaging, dynamic contrast enhanced magnetic resonance imaging and spectroscopy. The prostate specimen was whole mount sectioned in a customized mold, allowing geometric alignment to magnetic resonance imaging. Tumors were mapped on magnetic resonance imaging and histopathology. Sensitivity, specificity, positive predictive value and negative predictive value of magnetic resonance imaging for cancer detection were calculated. In addition, the effects of tumor size and Gleason score on the sensitivity of multiparametric magnetic resonance imaging were evaluated. The positive predictive value of multiparametric magnetic resonance imaging to detect prostate cancer was 98%, 98% and 100% in the overall prostate, peripheral zone and central gland, respectively. The sensitivity of magnetic resonance imaging sequences was higher for tumors larger than 5 mm in diameter as well as for those with higher Gleason scores (greater than 7, p <0.05). Prostate magnetic resonance imaging at 3T allows for the detection of prostate cancer. A multiparametric approach increases the predictive power of magnetic resonance imaging for diagnosis. In this study accurate correlation between multiparametric magnetic resonance imaging and histopathology was obtained by the patient specific, magnetic resonance imaging based mold technique.

Accuracy of high resolution (1.5 tesla) pelvic phased array magnetic resonance imaging (MRI) in staging prostate cancer in candidates for radical prostatectomy: Results from a prospective study

ObjectiveTo evaluate the role of pelvic phased array MRI in staging prostate cancer (CaP). Materials and methodsWe prospectively collected data over 12 months on CaP patients who underwent preoperative MR imaging with a pelvic phased array before radical prostatectomy. MR images were analyzed prospectively by 2 radiologists. MR imaging findings were then correlated with pathologic findings. ResultsOverall, 101 patients were included with a mean PSA level of 8 (range 1.8–30). Reader 1 (AUC 0.895, 95% CI 0.791–0.999) had a higher performance than reader 2 (AUC 0.687, 95% CI, 0.555–0.819) and than DRE (AUC 0.728, 95% CI, 0.599–0.857) in discriminating T2 from T3 CaP (P = 0.01). The κ-index of inter-observer agreement was 0.56. A model that combines MRI findings, DRE, PSA, and Gleason score was the most competitive for staging (AUC 0.895, 95% CI, 0.791–0.999). For the multivariate analysis, 3 criteria were significantly associated with extracapsular extension: asymmetry of the neuro-vascular bundles (P = 0.001), asymmetric enhancement of neurovascular bundles (P = 0.02), and bulging of the capsule (P = 0.0003). ConclusionPelvic phased array MRI presented satisfying results in its ability to adequately stage CaP and notably in detecting the extracapsular extension of tumors. It is likely to provide reliable information but rather in the hands of an experienced radiologist.

The ability of phased-array MRI in preoperative staging of primary rectal cancer: correlation with histopathological results

This study evaluated the accuracy of phased-array magnetic resonance imaging (MRI) for preoperative local tumor staging in primary rectal cancer and emphasized the importance of the preoperative differentiation of T2 tumors from T3 tumors so the appropriate treatment can be applied. Twenty-four patients with primary rectal cancer were examined preoperatively using 1.5 T MRI with a phased-array coil. Multiplanar T2-weighted images were obtained. Rectum anatomy, depth of tumor invasion, mesorectal involvement and lymph nodes were assessed. All patients underwent radical surgery. The histological sections were evaluated microscopically. The correlation of magnetic resonance imaging and histopathology was assessed using the kappa statistic. Overstaging with MRI was compared with Fischer's exact test. Histopathological examination of the tumors revealed adenocarcinoma. When the tumors were staged, there was one patient with a pT1 tumor, six patients with pT2 tumors, and 17 patients with pT3 tumors. Using MRI, four patients with pT2 were overstaged as T3, and one patient with pT3 was overstaged as T4. In the remaining cases (one pT1, two pT2, and 16 pT3), MRI correctly assessed the stage of transmural invasion. The accuracy of T staging and metastatic lymph node detection with MRI was calculated as 79.2% and 58.5%, respectively. Phased-array MRI is a valuable technique for the preoperative staging of rectal cancer, especially in the differentiation of T2 and T3 tumors.

3T versus 1.5T phased‐array MRI in the presurgical work‐up of patients with partial epilepsy of uncertain focus

To study 3T compared to 1.5T phased array magnetic resonance imaging (MRI) in the presurgical work-up of patients with epilepsy with complex focus localization. In all, 37 patients (>10 years) in preoperative work-up for epilepsy surgery were offered 3T in addition to 1.5T MRI if ambiguity existed about the epileptic focus. Scans were randomly reviewed by two observers, blinded for prior imaging, patient-identifying information, and each other's assessments, followed by a consensus meeting. The number of abnormal scans, detected lesions, and interobserver agreement were calculated and compared. The final consensus was compared to original scan reports. One observer identified 22 lesions in both 3 and 1.5T scans, while the second identified more lesions in 1.5T scans (28 vs. 20). 3T MRI had better interobserver agreement. 3T revealed more dysplasias, while 1.5T revealed more tissue loss and mesial temporal sclerosis (MTS). The final consensus yielded 29 lesions, whereas original reports identified only 17 lesions. The 3T scans revealed different lesions compared to 1.5T. Patients can benefit most from 3T scans when a dysplasia is suspected. Reevaluation by another experienced neuroradiologist is advised in case of negative or equivocal MRIs.

Endorectal ultrasonography versus phased-array magnetic resonance imaging for preoperative staging of rectal cancer

To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma. Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma. The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases using phased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively. ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.

Optimal Methods for Staging Rectal Cancer

At present, several modalities exist for the preoperative staging of rectal lesions, including computed tomography (CT), body coil or endorectal coil magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) done by rigid or flexible probes, and positron emission tomography (PET). Staging accuracy for CT ranges from 53% to 94% for T-stage accuracy and from 54% to 70% for N-stage accuracy. Improved CT accuracy is observed at higher disease stages. Body coil MRI has shown T- and N-stage accuracy ranging from 59% to 95% and 39% to 95%, respectively. Endorectal coil MRI has shown improved T- and N-stage accuracy, with rates of 66% to 91% and 72% to 79%, respectively. The development of phased-array MRI, combining high spatial resolution with a larger field of view, offers promise to improve on these rates. EUS, considered the current gold standard, has shown T-stage accuracy ranging from 75% to 95%, with N-stage accuracy ranging from 65% to 80%. Flexible EUS probes have the advantage of being able to access and sample iliac nodes. Recent studies also suggest that three-dimensional EUS may provide greater accuracy than conventional two-dimensional EUS. Limited studies exist on the use of PET in primary tumor staging. PET may upstage disease in 8% to 24% of patients and has also been used in posttreatment restaging and surveillance. Postradiation edema, necrosis, and fibrosis seem to decrease restaging accuracy in all modalities. This article reviews the current literature about the staging accuracy of the various modalities and suggests a staging algorithm for rectal cancer.

Comparison of Phased-Array 3.0-T and Endorectal 1.5-T Magnetic Resonance Imaging in the Evaluation of Local Staging Accuracy for Prostate Cancer

To retrospectively evaluate local staging accuracy for prostate cancer at 3.0-T magnetic resonance imaging (MRI) by comparing with that at 1.5-T MRI. Two groups, each consisting of 54 patients, were included by matching for age, prostate specific antigen, and Gleason score. Before radical prostatectomy, 1 group underwent 3.0-T MRI using a phased-array coil, and the other 1.5-T MRI using an endorectal coil. T2-weighted MR images at 3.0 and 1.5 T were analyzed in consensus by 2 radiologists, and their staging accuracy was compared with histology. Artifact and overall image quality were compared at both 3.0 and 1.5 T. Accuracy for T3 stage at 3.0 and 1.5 T were 72% (39/54) and 70% (38/54), respectively (P > 0.05). The 3.0-T MRI had a lower incidence of MR artifacts than the 1.5-T MRI (P < 0.05). However, overall imaging quality at both 3.0 and 1.5 T had no significant difference (P > 0.05). The 3.0-T phased-array MRI is equivalent to the 1.5-T endorectal MRI in evaluating local staging accuracy for prostate cancer without significant loss of imaging quality.

Dynamic Contrast Enhanced, Pelvic Phased Array Magnetic Resonance Imaging of Localized Prostate Cancer for Predicting Tumor Volume: Correlation With Radical Prostatectomy Findings

We assessed the value of pelvic phased array dynamic contrast enhanced magnetic resonance imaging for predicting the intraprostatic location and volume of clinically localized prostate cancers. Suspicious areas on prospective pre-biopsy magnetic resonance imaging in 24 patients were assigned a magnetic resonance imaging malignancy score and located with respect to anatomical features, gland side, and transition and peripheral zone boundaries. The largest surface area and volume were measured. These magnetic resonance imaging findings were compared with radical prostatectomy specimen histopathology findings. Histopathology maps detected 56 separate cancer foci. The largest tumor focus was located in the peripheral zone in 14 patients and in the transition zone in 10. T1-weighted dynamic contrast enhanced magnetic resonance imaging identified 30 of the 39 tumor foci greater than 0.2 cc and 27 of the 30 greater than 0.5 cc. T2-weighted sequences were suspicious in 22 of 30 foci greater than 0.2 cc that were identified by T1-weighted dynamic contrast enhanced magnetic resonance imaging sequences. Sensitivity, specificity, and positive and negative predictive values for cancer detection by magnetic resonance imaging were 77%, 91%, 86% and 85% for foci greater than 0.2 cc, and 90%, 88%, 77% and 95% for foci greater than 0.5 cc, respectively. Median focus volume was 1.37 cc (range 0.338 to 6.32) for foci greater than 0.2 cc detected by magnetic resonance imaging in the peripheral zone and 0.503 cc (range 0.337 to 1.345) for those not detected by magnetic resonance imaging (p <0.05). Corresponding median values for transition zone foci were 2.54 (range 0.75 to 16.87) and 0.435 (range 0.26 to 0.58). Pre-biopsy pelvic phased array dynamic contrast enhanced magnetic resonance imaging is an accurate technique for detecting and quantifying intracapsular transition or peripheral zone tumor foci greater than 0.2 cc. It has promising implications for cancer detection, prognosis and treatment.