Saroja Adusumilli

MR Imaging of Hepatocellular Carcinoma in the Cirrhotic Liver: Challenges and Controversies

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.

Characterization of Pancreatic Tumor Motion Using Cine MRI: Surrogates for Tumor Position Should Be Used With Caution

PURPOSE Our current understanding of intrafraction pancreatic tumor motion due to respiration is limited. In this study, we characterized pancreatic tumor motion and evaluated the application of several radiotherapy motion management strategies. METHODS AND MATERIALS Seventeen patients with unresectable pancreatic cancer were enrolled in a prospective internal review board-approved study and imaged during shallow free-breathing using cine MRI on a 3T scanner. Tumor borders were agreed on by a radiation oncologist and an abdominal MRI radiologist. Tumor motion and correlation with the potential surrogates of the diaphragm and abdominal wall were assessed. These data were also used to evaluate planning target volume margin construction, respiratory gating, and four-dimensional treatment planning for pancreatic tumors. RESULTS Tumor borders moved much more than expected. To provide 99% geometric coverage, margins of 20 mm inferiorly, 10 mm anteriorly, 7 mm superiorly, and 4 mm posteriorly are required. Tumor position correlated poorly with diaphragm and abdominal wall position, with patient-level Pearson correlation coefficients of -0.18-0.43. Sensitivity and specificity of gating with these surrogates was also poor, at 53%-68%, with overall error of 35%-38%, suggesting that the tumor may be underdosed and normal tissues overdosed. CONCLUSIONS Motion of pancreatic tumor borders is highly variable between patients and larger than expected. There is substantial deformation with breathing, and tumor border position does not correlate well with abdominal wall or diaphragmatic position. Current motion management strategies may not account fully for tumor motion and should be used with caution.

MRI of Sonographically Indeterminate Adnexal Masses

OBJECTIVE The purpose of this study was to assess the ability of MRI to characterize sonographically indeterminate adnexal masses and to define the sonographic features contributing to indeterminate diagnoses. MATERIALS AND METHODS Two blinded radiologists retrospectively reviewed the MRI examinations of 87 patients with 95 sonographically indeterminate adnexal masses. Reviewers determined the origin of a mass, its tissue content (cystic, solid, complex cystic, or cystic and solid), tissue characteristics (fat, blood, fibrous, or leiomyomatous), and benignity versus malignancy. Sonograms were reviewed by three reviewers to determine the origin of a mass, its tissue content, and reasons for an indeterminate diagnosis. Sensitivity and specificity of MRI were calculated, and agreement of sonography and MRI with the final diagnosis was determined using kappa statistics. The final diagnosis was determined by histopathology, surgical findings, or imaging or clinical follow-up. RESULTS The sensitivity of MRI for identifying malignancy (n = 5) was 100% and its specificity for benignity (n = 90) was 94%. Excellent agreement was seen between MRI and the final diagnosis for determining the origin (kappa = 0.93), tissue content (kappa = 0.98), and tissue characteristics (kappa = 0.91) of a mass. Sonography had poor agreement with the final diagnosis for the origin (kappa = 0.19) and tissue content (kappa = 0.33) of a mass. The main reasons for indeterminate sonographic diagnoses were the inability to determine origin because of location and large mass size and the appearances of purely solid or complex cystic masses. CONCLUSION Sonographically indeterminate adnexal masses of uncertain origin and solid or complex cystic content benefit from further evaluation with MRI, which is highly accurate for identifying the origin of a mass and characterizing its tissue content, obviating surgery.

How well does applicant rank order predict subsequent performance during radiology residency

RATIONALE AND OBJECTIVES Residency selection committees expend substantial time and resources on assessing the quality of residency applicants to derive an appropriate rank order for the National Residency Matching Program. The authors determined whether there is a relationship between the rank number or rank percentile of applicants selected for a residency training program and subsequent radiology residency performance. MATERIALS AND METHODS Records of radiology residents completing their residency between 1991 and 1998 were reviewed. Available rank numbers and rank percentiles for each resident were compared with subsequent performance, as assessed subjectively by 4th-year radiology rotation evaluation forms and retrospective recall of four senior faculty members and objectively by numerical and percentile scores on the written portion of the American Board of Radiology (ABR) examinations. Correlation coefficients were obtained for each comparison. RESULTS Rank number and rank percentile were not significantly correlated with 4th-year resident rotation evaluations or ABR written examination scores or percentiles. A small correlation existed between rank order and retrospective evaluation of resident performance by the four senior faculty. CONCLUSION Applicant rank number and rank percentile do not correlate with subsequent radiology residency performance as assessed on rotation evaluation forms or the ABR written examinations.

3D excretory MR urography: Improved image quality with intravenous saline and diuretic administration

To assess the effect of diuretic administration on the image quality of excretory magnetic resonance urography (MRU) obtained following intravenous hydration, and to determine whether intravenous hydration alone is sufficient to produce diagnostic quality studies of nondilated upper tracts.

Sonography of Uterine Abnormalities in Postpartum and Postabortion Patients A Potential Pitfall of Interpretation

The interpretation of postpartum and postabortion uterine abnormalities on sonography can be challenging. The purpose of this study was to identify misleading imaging features that lead to inclusion of a uterine arteriovenous malformation (AVM) in the differential diagnosis of a uterine abnormality because consideration of this diagnosis can potentially alter patient treatment.

Apparent wall thickening of cystic renal lesions on MRI

To show that cystic renal lesions that would otherwise meet criteria for simple cysts can demonstrate perceptible walls or increased wall thickness on MRI, sometimes causing these lesions to be “upgraded.” It was hypothesized that thickening of cyst walls on MRI can be artifactual, due to data truncation, applied filtering, and low signal‐to‐noise ratio (SNR).

MRI Endorectal Coil

Endorectal coil MRI has recently shown promise of improving the accuracy of imaging in the staging of bladder cancer. Specifically, endorectal coil MRI has demonstrated the ability to image at the submucosal and muscle layers, by overcoming limitations of insufficient spatial resolution and poor signal-to-noise that previously hindered its ability to differentiate individual layers of the bladder wall. This chapter reviews the evolution of MR-imaging techniques in bladder cancer staging over the past decade, leading to the most recently published work on endorectal coil MRI. Topics will include high resolution T2-weighted imaging, dynamic contrast-enhanced MRI, endorectal coil principles and technique, and submucosal linear enhancement, all of which have contributed to the recently improved ability of MRIs to accurately assess the relationship of bladder neoplasm to the bladder wall.