Arumugam Rajesh

Assessment of Aggressiveness of Prostate Cancer: Correlation of Apparent Diffusion Coefficient With Histologic Grade After Radical Prostatectomy

OBJECTIVE The purpose of this article is to evaluate the relationship between apparent diffusion coefficient (ADC) values, tumor volume, and total Gleason grade in patients with prostate cancer before radical prostatectomy. MATERIALS AND METHODS A total of 110 patients with prostate cancer who had undergone endorectal prostate MRI at 1.5 T before radical prostatectomy were included. ADC values were derived by drawing a region of interest on the histologically confirmed tumors. Tumor volume was obtained by manual segmentation on T2-weighted images (T2WIs) and ADC maps. The relationship between the ADC value or tumor volume and the Gleason grade was assessed by using multivariate mixed linear and effect models. Multivariate analysis was performed to evaluate the accuracy of ADC and tumor volume in determining the aggressiveness of prostate cancer. RESULTS A total of 197 tumors were studied; 128 (65%) tumors were found in the peripheral zone and 69 (35%) were found in the central gland. The ADC value was found to be negatively correlated with the Gleason grade (r = -0.39 for peripheral zone cancer). Higher ADC values were found to be associated with lower Gleason grades in the peripheral zone prostate cancers. No association was found in the central zone prostate cancers. Both ADC values and tumor volumes were found to significantly predict tumor aggressiveness, specifically in the peripheral zone (area under the curve, 0.78). CONCLUSION ADC values were found to be negatively correlated with the postsurgical Gleason grade in patients with prostate cancer. Our results show that ADC values might help to predict prostate cancer, especially for tumors in the peripheral zone. Given the substantial overlap in the ADC values, the addition of other MR parameters, such as volumetry, and technical improvements in diffusion-weighted imaging might improve accuracy in the stratification of patients.

Overview of Dynamic Contrast-Enhanced MRI in Prostate Cancer Diagnosis and Management

OBJECTIVE This article is a primer on the technical aspects of performing a high-quality dynamic contrast-enhanced MRI (DCE-MRI) examination of the prostate gland. CONCLUSION DCE-MRI is emerging as a useful clinical technique as part of a multi-parametric approach for evaluating the extent of primary and recurrent prostate cancer. Performing a high-quality DCE-MRI examination requires a good understanding of the technical aspects and limitations of image acquisition and postprocessing techniques.

Cystic Lesions of the Pancreas

Background/Aims: Due to enhanced imaging modalities, pancreatic cysts are being increasingly detected, often as an incidental finding. They comprise a wide range of differing underlying pathologies from completely benign through premalignant to frankly malignant. The exact diagnostic and management pathway of these cysts remains problematic and this review attempts to provide an overview of the pathology underlying pancreatic cystic lesions and suggests appropriate methods of management. Methods: A search was undertaken with a Pubmed database to identify all English articles using the keywords ‘pancreatic cysts’, ‘serous cystadenoma’, ‘intraductal papillary mucinous tumour’, ‘pseudocysts’, ‘mucinous cystic neoplasm’ and ‘solid pseudopapillary tumour’. Results: The mainstay of assessment of pancreatic cysts is cross-sectional imaging incorporating CT and MRI. Fine-needle aspiration (FNA) (often with endoscopic ultrasound) may provide valuable additional information but can lack sensitivity. Symptomatic cysts, increasing age and multilocular cysts (with a solid component and thick walls) are predictors of malignancy. A raised cyst aspirate CEA, CA 19-9 and mucin content (including abnormal cytology), if present, can accurately distinguish premalignant and malignant cysts from benign ones. Conclusion: In summary, all patients with pancreatic cystic lesions, whether asymptomatic or symptomatic, must be thoroughly investigated to ascertain the underlying nature of the cyst. Small asymptomatic cysts (<3 cm) with no suspicious features on imaging or FNA may be safely followed up. Follow-up should continue for at least 4 years, with a repeat FNA if needed. An algorithm for the management of pancreatic cystic tumours is also suggested.

Renal oncocytoma: CT features cannot reliably distinguish oncocytoma from other renal neoplasms.

AIM To retrospectively review the computed tomography (CT) imaging features of a series of histologically confirmed renal oncocytomas and to determine whether imaging features are predictive of this subtype of benign renal epithelial tumour. MATERIALS AND METHODS From May 2001 to October 2007, 21 patients with 28 renal masses, confirmed as renal oncocytoma on histological examination of the resection specimen, were identified from the pathology database at our institution. The preoperative imaging findings were retrospectively analysed to determine characteristic features, if any, to predict this rare subtype of benign renal tumour. RESULTS There were 11 female and 10 male patients and the age at presentation ranged from 40-80 years (mean age 65.9 years). The size of the masses ranged from 1.2-12 cm in diameter (mean diameter 4.9 cm). All masses showed contrast enhancement. In 18 (64.3%) lesions the enhancement of the tumour was isodense to renal cortex. Ten (35.7%) lesions were hypodense to renal cortex. In three (10.7%) lesions, a well-defined stellate central scar was seen at CT and confirmed pathologically. In two (7.1%) lesions, a central scar was identified pathologically, but not seen on CT. The size of the central scars ranged from 10-29 mm diameter on CT. Twenty-two (78.6%) lesions did not demonstrate a scar on CT or pathologically. None of the patients had regional lymphadenopathy or distant metastasis. CONCLUSION Renal oncocytoma is typically described as being hypervascular and homogeneous, with a characteristic central stellate scar on CT. The present study demonstrates that these imaging features are found in only a small proportion of these tumours. Therefore, imaging characteristics alone are unreliable when differentiating between oncocytoma and renal cell carcinoma, and histopathological diagnosis remains the reference standard.

Prostate MRI and 3D MR Spectroscopy: How We Do It

OBJECTIVE This review is a primer on the technical aspects of performing a high-quality MRI and MR spectroscopic imaging examination of the prostate. CONCLUSION MRI and MR spectroscopic imaging are useful tools in the localization, staging, and functional assessment of prostate cancer. Performing a high-quality MR spectroscopic examination requires understanding of the technical aspects and limitations of spectral acquisition, postprocessing techniques, and spectral evaluation.

MR Enterography of Crohn Disease: Part 1, Rationale, Technique, and Pitfalls

OBJECTIVE The purpose of this article is to review the technique of performing MR enterography examinations and to review the imaging findings suggestive of Crohn disease. This article will also allow the reader to self-assess and improve his or her skills in the performance and interpretation of MR enterography examinations. CONCLUSION MRI plays a valuable role in providing accurate information about the severity of and complications related to Crohn disease and can help in guiding surgical or medical treatment.

MR Enterography of Crohn Disease: Part 2, Imaging and Pathologic Findings

OBJECTIVE The purpose of this article is to review MR enterography technique and imaging findings suggestive of Crohn disease on these examinations. This article will also allow the reader to self-assess and improve his or her skills in the performance and interpretation of MR enterography examinations. CONCLUSION This article reviews the technique of performing MR enterography examinations. MRI plays a valuable role in providing accurate information about severity of and complications related to Crohn disease and can help in guiding surgical or medical treatment.

Urinary bladder cancer: Role of MR imaging

Urinary bladder cancer is a heterogeneous disease with a variety of pathologic features, cytogenetic characteristics, and natural histories. It is the fourth most common cancer in males and the tenth most common cancer in females. Urinary bladder cancer has a high recurrence rate, necessitating long-term surveillance after initial therapy. Early detection is important, since up to 47% of bladder cancer-related deaths may have been avoided. Conventional computed tomography (CT) and magnetic resonance (MR) imaging are only moderately accurate in the diagnosis and local staging of bladder cancer, with cystoscopy and pathologic staging remaining the standards of reference. However, the role of newer MR imaging sequences (eg, diffusion-weighted imaging) in the diagnosis and local staging of bladder cancer is still evolving. Substantial advances in MR imaging technology have made multiparametric MR imaging a feasible and reasonably accurate technique for the local staging of bladder cancer to optimize treatment. In addition, whole-body CT is the primary imaging technique for the detection of metastases in bladder cancer patients, especially those with disease that invades muscle.

Bladder cancer: Evaluation of staging accuracy using dynamic MRI

AIM To assess the accuracy of magnetic resonance imaging (MRI) in staging bladder cancer and to assess whether dynamic gadolinium-enhanced sequences have any added benefit in staging. MATERIALS AND METHODS Over a 22 month period, the MRI findings of 100 consecutive patients with histologically proven transitional cell carcinoma (TCC) of the bladder were reviewed. The T stage was assessed independently on T2-weighted imaging alone and in combination with gadolinium-enhanced MRI. The final histological diagnosis was considered the reference standard. Statistical analysis was performed to ascertain stage-by-stage accuracy. Accuracy of MRI in differentiating superficial (≤ T1) from invasive (≥ T2) and in differentiating organ-confined (≤ T2) from non-organ-confined (≥ T3) disease was assessed. RESULTS On a stage-by-stage basis, tumours were correctly staged using MRI in 63% of patients (observed agreement=0.63, weighted kappa=0.57). The sensitivity and specificity of MRI to differentiate between superficial (≤ T1) from invasive (≥ T2) disease was 78.2 and 93.3%. The observed agreement for this group was 85% (kappa=70%; p<0.0001). The sensitivity and specificity of MRI to differentiate between organ-confined (≤ T2) from non-organ confined (≥ T3) disease was 90.5 and 60%. The observed agreement for this group was 89% (kappa=30%; p<0.01). Gadolinium-enhanced images improved staging in only three patients. CONCLUSION In the present study MRI was found to be a moderately accurate tool in assessing the T stage. Agreement on a stage-by-stage basis was good. Agreement for differentiating between non-invasive versus muscle-invasive disease was good and that for organ-confined versus non-organ-confined disease was fair. Routine use of gadolinium-enhanced images is not routinely required.

A clinically relevant approach to imaging prostate cancer: review.

The zonal anatomy of the prostate is likened to a cone containing a scoop of ice cream [5, 6]. The cone is the peripheral zone and makes up 70% of the prostate gland by volume in young men. The ducts of the peripheral zone glands drain to the distal prostatic urethra. The scoop of ice cream is the central zone and makes up 25% of the prostate gland volume in young men. The ejaculatory ducts traverse the central zone, and the ducts of the central zone drain to the region of the verumontanum clustered around the entry of the ejaculatory ducts. The remaining 5% of the prostate consists of the transition zone, which is composed of two small bulges of tissue that surround the anterior and lateral parts of the proximal urethra in a horseshoelike fashion (Fig. 1). This two-compartment model is deficient anteriorly where the peripheral zone is interrupted by the anterior fibromuscular stroma, a band of smooth muscle mixed with fibrous tissue that forms a thick shield over the anterior aspect of the gland. As a result, the peripheral zone lies predominantly lateral and posterior to the central zone. The prostate zones are defined histologically and therefore many prostatic diseases have a zonal distribution. Seventy percent of adenocarcinomas arise in the peripheral zone and 20% of adenocarcinomas arise in the transition zone, while only 10% of adenocarcinomas arise in the central zone. Prostate adenocarcinomas arise in the glandular components of the prostate [5].