Faculty Bibliography

PURPOSE: To assess the accuracy of glomerular filtration rate (GFR) measurements obtained with low-contrast agent dose dynamic contrast material-enhanced magnetic resonance (MR) renography in patients with liver cirrhosis who underwent routine liver MR imaging, with urinary clearance of technetium 99m ((99m)Tc) pentetic acid (DTPA) as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved. Written informed patient consent was obtained. Twenty patients with cirrhosis (14 men, six women; age range, 41-70 years; mean age, 54.6 years) who were scheduled for routine 1.5-T liver MR examinations to screen for hepatocellular carcinoma during a 6-month period were prospectively included. Five-minute MR renography with a 3-mL dose of gadoteridol was performed instead of a routine test-dose timing examination. The GFR was estimated at MR imaging with use of two kinetic models. In one model, only the signal intensities in the aorta and kidney parenchyma were considered, and in the other, renal cortical and medullary signal intensities were treated separately. The GFR was also calculated by using serum creatinine levels according to the Cockcroft-Gault and modification of diet in renal disease (MDRD) formulas. All patients underwent a (99m)Tc-DTPA urinary clearance examination on the same day to obtain a reference GFR measurement. The accuracies of all MR- and creatinine-based GFR estimations were compared by using Wilcoxon signed rank tests. RESULTS: The mean reference GFR, based on (99m)Tc-DTPA clearance, was 74.9 mL/min/1.73 m(2) +/- 27.7 (standard deviation) (range, 10.3-120.7 mL/min/1.73 m(2)). With both kinetic models, 95% of MR-based GFRs were within 30% of the reference values, whereas only 40% and 60% of Cockcroft-Gault- and MDRD-based GFRs, respectively, were within this range. MR-based GFR estimates were significantly more accurate than creatinine level-based estimates (P < .001). CONCLUSION: GFR assessment with MR imaging, which outperformed the Cockcroft-Gault and MDRD formulas, adds less than 10 minutes of table time to a clinically indicated liver MR examination without ionizing radiation. Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101338/-/DC1

Details on the 28-year treatment history of a patient with an endocrine-responsive breast cancer are provided. She was originally diagnosed as having a T1N0M0 cancer after a modified radical mastectomy at age 41. Fifteen years later, in 1998, she presented with hemoptysis and pleuritic chest pain: a 10 cm right atrial tumor and estrogen receptor (ER) positive endobronchial and adjacent lung parenchyma adenocarcinoma were documented. Epithelial markers normalized as she manifested a partial response (PR) lasting 3 years with tamoxifen treatment. From 2001 to 2007 she benefitted from exemestane treatment. Upon progression in the previous lung area and left adrenal, exemestane withdrawal led to transient decrease in markers. Six months later (in July 2008), with growth in her adrenal tumor, laparoscopic adrenalectomy was performed: in addition to ER positivity, the tumor showed Her2 overexpression and amplification. She has subsequently had some control of disease with fulvestrant, letrozole + trastuzumab, and subsequently letrozole + lapatinib. In addition to the chronicity of disease, this history illustrates the expanding range of treatments available for endocrine-responsive breast cancer commensurate to our greater understanding of tumor biology

Purpose. We quantify the additional radiation exposure in terms of effective dose incurred by patients in the CT portion of SPECT/CT examinations. Methods. The effective dose from a variety of common nuclear medicine procedures is calculated and summarized. The extra exposure from the CT portion of the examination is summarized by examination and body part. Two hundred forty-eight scans from 221 patients are included in this study. The effective dose from the CT examination is also compared to average background radiation. Results. We found that the extra effective dose is not sufficient to cause deterministic effects. However, the stochastic effects may be significant, especially in patients undergoing numerous follow-up studies. The cumulative effect might increase the radiation exposure compared to patient management with SPECT alone. Conclusions. While the relative increase in radiation exposure associated with SPECT/CT is generally considered acceptable when compared with the benefits to the patient, physicians should make every effort to minimize this effect by using proper technical procedures and educating patients about the exposure they will receive.

An 81-year-old woman with renal cell carcinoma (RCC) underwent F-18 FDG PET/CT for staging, which demonstrated intense uptake in a dilated azygos vein, in the inferior vena cava (IVC), and in the known large left RCC. Contrast-enhanced CT of the chest and abdomen obtained in the days following confirmed the presence of tumor thrombus in the dilated azygos system, IVC, and the contiguous left renal vein. This case serves as a reminder that special attention should always be paid to the renal vein, IVC, and adjoining venous drainage pathways for abnormal FDG activity while imaging RCC, as the diagnosis of venous tumor thrombus has important clinical ramifications.