Gopal Vijayaraghavan

Digital Breast Tomosynthesis: State of the Art

This topical review on digital breast tomosynthesis (DBT) is provided with the intent of describing the state of the art in terms of technology, results from recent clinical studies, advanced applications, and ongoing efforts to develop multimodality imaging systems that include DBT. Particular emphasis is placed on clinical studies. The observations of increase in cancer detection rates, particularly for invasive cancers, and the reduction in false-positive rates with DBT in prospective trials indicate its benefit for breast cancer screening. Retrospective multireader multicase studies show either noninferiority or superiority of DBT compared with mammography. Methods to curtail radiation dose are of importance. (©) RSNA, 2015.

Imaging of Brown Fat Associated with Adrenal Pheochromocytoma

The association of adrenal pheochromocytoma and brown fat has been described in the pathology literature and scantily in the radiology literature. We present a case of diffuse collection of brown fat in both perinephric spaces associated with left adrenal pheochromocytoma, and describe the computed tomography and magnetic resonance imaging findings.

Imaging-guided Parenchymal Liver Biopsy: How We Do It

Liver biopsies are performed for both focal and nonfocal lesions (parenchymal). In our center, majority of liver biopsies are performed for parenchymal liver disease. Parenchymal liver biopsy plays a key role in the diagnosis of various diffuse liver dysfunctions. Results of the biopsy help grade the disease, facilitating prognostication, which helps in planning specific treatment strategies. Imaging guidance is gaining wide acceptance as the standard procedure. Ultrasound (US) guidance is currently considered the most cost-effective and safe way to perform parenchymal liver biopsies. Radiologists worldwide and particularly in the United States are increasingly performing this procedure. Radiologists performing biopsies generally use the cutting needle. Different needle sizes, techniques and preference for biopsy of the right or left lobe have been described. We attribute these preferences to prior training and individual radiologists comfort level. We describe the algorithm followed at our institution for performing percutaneous US-guided parenchymal liver biopsy. While clinical societies have recommended a minimum of 40 liver biopsies as a requirement for proficiency of clinicians, specific to radiology trainees/fellows interested in pursuing a career in intervention, we feel a total of 20 liver biopsies (includes assisted and independently performed biopsies under supervision) should be adequate training.

Addenda to the radiology report: what are we trying to convey?

PURPOSE The aims of this paper are to describe addenda to radiology reports and to discuss the communication gaps in radiology addenda reaching referring physicians. The authors examine impediments to compliance with an addendum policy and suggest possible solutions. METHODS A total of 62,500 radiology reports were reviewed to analyze the occurrence of report addenda. Addenda types were separated into clinical, generated by radiologists, and administrative (for billing or regulatory reasons). Two radiologists reviewed all clinical addenda and classified them as significant or not significant. Significant addenda were further analyzed for various aspects. An e-mail survey was also conducted to assess prevailing practices in academic departments of radiology. RESULTS There were 1,069 reports with addenda (1.7%). Of these, 575 were generated by radiologists. Forty-nine (8.5%) were for clinically significant errors and 526 (91.5%) were not. Of the 49 significant addenda, 9 (18%) were fully compliant with departmental addendum policies, 27 (55%) were noncompliant, and 13 (27%) were partially compliant. Of the 49 clinically significant addenda, 17 (55%) were dictated within 1 hour and 40 (82%) within 24 hours of the finalized original reports. CONCLUSIONS Poor compliance with an addendum policy was found. The reasons for noncompliance and possible remedies are discussed, with the hope of beginning a dialogue in the radiology literature on the risks of poor communication processes and the benefits of full implementation of well thought-out addendum policies.

Unusual Complication After Left-Lobe Liver Biopsy for Diffuse Liver Disease: Severe Bleeding From the Superior Epigastric Artery

OBJECTIVE Imaging-guided parenchymal liver biopsy for diffuse liver disease is increasingly performed via an epigastric route from the left lobe, as opposed to the more traditional intercostal right-sided approach. MATERIALS AND METHODS We conducted a retrospective analysis of all liver biopsies performed at our department for 3 years (July 2007 through June 2010). A total of 1028 liver biopsies were performed during this period. Of these, 776 biopsies were performed for diffuse medical liver disease. Electronic medical records were reviewed for any documented complications. RESULTS We identified six cases (0.8%) of documented significant bleeding after 776 biopsies. All bleeding complications were associated with the left-sided epigastric approach. No documented case of major bleeding from the right-sided approach was recorded during the same period. We describe four patients with severe bleeding complications in which classic imaging features were noted on CT, pointing to injury of the superior epigastric artery as the possible cause of the bleeding. CONCLUSION It is important to recognize the subtle CT signs of superior epigastric artery bleeding because the traditional femoral approach with angiography of the hepatic and portal vessels may not reveal active bleeding. The superior epigastric artery, rather than the hepatic arteries, should be evaluated. A brachial approach for the angiogram may be the more optimal technique.

The Relevance of Ultrasound Imaging of Suspicious Axillary Lymph Nodes and Fine-needle Aspiration Biopsy in the Post-ACOSOG Z11 Era in Early Breast Cancer

RATIONALE AND OBJECTIVES Evaluation of nodal involvement in early-stage breast cancers (T1 or T2) changed following the Z11 trial; however, not all patients meet the Z11 inclusion criteria. Hence, the relevance of ultrasound imaging of the axilla and fine-needle aspiration biopsy (FNA) in early-stage breast cancers was investigated. MATERIALS AND METHODS In this single-center, retrospective study, 758 subjects had pathology-verified breast cancer diagnosis over a 3-year period, of which 128 subjects with T1 or T2 breast tumors had abnormal axillary lymph nodes on ultrasound, had FNA, and proceeded to axillary surgery. Ultrasound images were reviewed and analyzed using multivariable logistic regression to identify the features predictive of positive FNA. Accuracy of FNA was quantified as the area under the receiver operating characteristic curve with axillary surgery as reference standard. RESULTS Of 128 subjects, 61 were positive on FNA and 65 were positive on axillary surgery. Sensitivity, specificity, positive predictive value, and negative predictive value of FNA were 52 of 65 (80%), 54 of 63 (85.7%), 52 of 61(85.2%), and 54 of 67 (80.5%), respectively. After adjusting for neoadjuvant chemotherapy between FNA and surgery, a positive FNA was associated with higher likelihood for positive axillary surgery (odds ratio: 22.7; 95% confidence interval [CI]: 7.2-71.3, P < .0001), and the accuracy of FNA was 0.801 (95% CI: 0.727-0.876). Among ultrasound imaging features, cortical thickness and abnormal hilum were predictive (P < .017) of positive FNA with accuracy of 0.817 (95% CI: 0.741-0.893). CONCLUSIONS Ultrasound imaging and FNA can play an important role in the management of early breast cancers even in the post-Z11 era. Higher weightage can be accorded to cortical thickness and hilum during ultrasound evaluation.

Renal biopsy: Comparative yield of cranial versus caudal needle trajectory. An ex vivo analysis

To compare the diagnostic quality of tissue cores obtained using cranial and caudal angulation of the renal biopsy needle. Comparison was made in terms of the number of glomeruli and proportion of renal cortex with medulla on pathological analysis.

Unifocal Invasive Lobular Carcinoma: Tumor Size Concordance Between Preoperative Ultrasound Imaging and Postoperative Pathology

Background: We systematically analyzed the extent of disease in unifocal invasive lobular carcinoma (ILC) using ultrasonography, with the histopathologic findings as the reference standard. Patients and Methods: In the present single‐institution retrospective study, 128 cases of ILC were identified during a 5‐year period. After exclusions, the analyzed cohort included 66 cases. Ultrasound measurements of the tumor extent along 3 axes were obtained. The tumor size was determined as the largest extent among the 3 axes and the tumor volume by ellipsoidal approximation. Pathology review provided the tumor size and volume. Correlation and regression analyses of tumor size and volume from the ultrasound and pathologic examinations were performed. The tumor stage from the ultrasound and pathologic examinations were used for the concordance analyses. Results: The median and quartiles (Q1, Q3) of tumor size from ultrasonography and pathology were 12.5 mm (Q1, 9 mm; Q3, 19 mm) and 17 mm (Q1, 12 mm; Q3, 25 mm), respectively. The corresponding data for tumor volume were 0.52 cm3 (Q1, 0.18 cm3; Q3, 1.92 cm3) and 1.04 cm3 (Q1, 0.45 cm3; Q3, 2.49 cm3). The ultrasound measurements correlated with the pathology‐reported tumor size (Spearman &rgr; = 0.678; P < .0001) and volume (Spearman &rgr; = 0.699; P < .0001). The ultrasound‐measured size and volume differed from the pathology‐reported size and volume (P < .0001; Wilcoxon signed ranks test). Concordance between the clinical tumor size stage from ultrasound (cT) and pathology tumor size stage (pT) varied with the pT stage (P = .0003, Fishers exact test), with the greatest concordance rate of 95.7% (95% confidence limit, 85.2%‐99.5%) observed for pT1 tumors. Conclusion: Ultrasonography underestimates the tumor size and volume, with the underestimation increasing for larger tumors. Hence, the concordance rate in tumor size stage between ultrasonography and pathology is tumor size dependent, with the greatest concordance rate observed for pT1 tumors.

SU-D-206-06: Task-Specific Optimization of Scintillator Thickness for CMOS-Detector Based Cone-Beam Breast CT

PURPOSE To optimize the cesium iodide (CsI:Tl) scintillator thickness in a complimentary metal-oxide semiconductor (CMOS)-based detector for use in dedicated cone-beam breast CT. METHODS The imaging task considered was the detection of a microcalcification cluster comprising six 220µm diameter calcium carbonate spheres, arranged in the form of a regular pentagon with 2 mm spacing on its sides and a central calcification, similar to that in ACR-recommended mammography accreditation phantom, at a mean glandular dose of 4.5 mGy. Generalized parallel-cascades based linear systems analysis was used to determine Fourier-domain image quality metrics in reconstructed object space, from which the detectability index inclusive of anatomical noise was determined for a non-prewhitening numerical observer. For 300 projections over 2π, magnification-associated focal-spot blur, Monte Carlo derived x-ray scatter, K-fluorescent emission and reabsorption within CsI:Tl, CsI:Tl quantum efficiency and optical blur, fiberoptic plate transmission efficiency and blur, CMOS quantum efficiency, pixel aperture function and additive noise, and filtered back-projection to isotropic 105µm voxel pitch with bilinear interpolation were modeled. Imaging geometry of a clinical prototype breast CT system, a 60 kV Cu/Al filtered x-ray spectrum from 0.3 mm focal spot incident on a 14 cm diameter semi-ellipsoidal breast were used to determine the detectability index for 300-600 µm thick (75µm increments) CsI:Tl. The CsI:Tl thickness that maximized the detectability index was considered optimal. RESULTS The limiting resolution (10% modulation transfer function, MTF) progressively decreased with increasing CsI:Tl thickness. The zero-frequency detective quantum efficiency, DQE(0), in projection space increased with increasing CsI:Tl thickness. The maximum detectability index was achieved with 525µm thick CsI:Tl scintillator. Reduced MTF at mid-to-high frequencies for 600µm thick CsI:Tl lowered the detectability index than 525µm CsI:Tl. CONCLUSION For the x-ray spectrum and imaging conditions considered, a 525µm thick CsI:Tl scintillator integrated with the CMOS detector is optimal for detecting microcalcification cluster. Funding support: Supported in part by NIH R01 CA195512. The contents are solely the responsibility of the authors and do not reflect the official views of the NIH or the NCI. Disclosures: SV, GV and AK - Research collaboration, Koning Corp., West Henrietta, NY.

Molecular Basis of Breast Cancer Imaging

Over the past decade, annually for women 50 years of age or older, the breast cancer incidence rate in the United States has ranged from 400 to 500 per 100 000 women and the breast cancer mortality rate has ranged from 60 to 80 per 100 000 women. Though there has been a decline in the breast cancer mortality in the past decade it continues to be the second leading cause of death after lung cancer in women over 40 years of age. Breast cancer continues to be a major health issue among women in the United States. Screening mammogram has significantly contributed to the reduction in mortality. However, screening mammogram has its own limitations. Its sensitivity is 80 % in fatty breasts but is substantially lower in dense breasts. On average nearly 30 % of women reporting for mammograms have dense breasts and 1 in 2 cancers in dense breasts are missed on mammograms due to the masking effect caused by overlapping tissues.