Sunday Case of the Day History : Patient presented for screening mammogram. The radiologist noted that there “increased motion on both CC views” limiting evaluation. MLO views were of good image quality. Authors : William Geiser, MS, DABR 1 MD Anderson Cancer Center, Houston TX Physics Figure #: 1 CC views on screening mammogram Figure #: 2 MLO views on screening mammogram 30 kVp 60 mAs 100 mA Thickness: 59 mm 17 pounds force 27 kVp 59 mAs 100 mA Thickness: 44 mm 11 pounds force 32 kVp 65 mAs 100 mA Thickness: 66 mm 24 pounds force 28 kVp 50 mAs 100 mA Thickness: 47 mm 10 pounds force Likely cause of the “increased motion” is? A.Patient Motion B.Poor Compression C.Long Exposure time D.Poor positioning

Findings : The patient was called back for repeat CC views due to poor image quality. Figure #3: CC views from initial exam. 1. Fig. 3A: RCC technical values were: 30 kVp, 60.5 mAs, 59 mm compressed breast thickness. 2. Fig. 3B: LCC technical factors were: 32 kVp, 65 mAs, 66 mm compressed breast thickness. 3. Fig. 4A RCC technical factors were: 27 kVp, 86 mAs, 40 mm compressed breast thickness. 4. Fig. 4B LCC technical factors were: 27 kVp, 84 mAs, 41 mm compressed breast thickness. Figure #4: Repeat CC views. A B AB RCC LCC RCC LCC

Diagnosis: B. Poor Compression making it hard for the radiologist to see fine detail in the image. Required that patient be called back for additional imaging.

As stated in the ACR Quality Control Manual section on Clinical Image Quality we compress for the following reasons: 1. Decreases breast thickness 2. Reduces dose 3. Reduces scatter 4. Reduces object unsharpness 5. Eliminates patient motion Discussion: Proper compression is important in mammography. The question is often asked “Why do we have to compress?” We compress for a variety of reasons. Even though the radiologist mentioned motion, patient motion is not the issue here, lack of compression is. A closer review of the images did not show any patient motion artifact (see Fig. 5). Fig 5A is a calcification seen in the RCC on the original image. Fig 5B is the same calcification on the repeated view. Neither exhibit patient motion artifact. Answer A patient motion is incorrect. Most mammography generators are limited to 100 mA due to the limitations of the focal spot size and anode material (0.1 mm and Molybdenum). The system used here is a Hologic Selenia which has a 100 mA generator. All of the exposure times are less than a second long. Answer C long exposure times is incorrect. The breast is positioned properly for the CC views, and if properly compressed would have spread out more leading to better visibility of the internal structure of the breast. Answer D patient positioning is incorrect. Figure 5: Calcification showing there is no patient motion A B

There are several things to note when comparing the under compressed and properly compressed views. Visibility of the internal structure of the breast is greatly improved. The image appears more sharp due to the spreading of the overlapping tissues and bringing structures closer to the detector. Lower kVp in the properly compressed breast leads to improved contrast in the image. Figure 6. Comparison of two RCC views 30 kVp 60.5 mAs 100 mA 57 mm 27 kVp 85.7 mAs 100 mA 40 mm

References/Bibliography: Hendrick, RE, Lawrence, B, Botsco, MA, et.al. American College of Radiology Mammography Quality Control Manual Section on Clinical Image Quality, 1999 Geiser WR, Haygood TM, Santiago L, Stephens T, Thames D, Whitman GJ. Challenges in Mammography: Part 1Artifacts in Digital Mammography. AJR Am J Roentgenol 197(12):W W1030, 12/2011