Characterisation of calcium compounds by linear attenuation- A MARS CT project of potential significance

in the diagnosis of breast disease

Rachel CullensMedical Imaging Lecturer, CPIT

Dr Anthony Butler, Dr Nanette Schleich and Syen Nik

DCIS

(Sickles, E., Radiology, 2000)

Breast Screening and Biopsy 1 in 8 women in NZ will develop breast cancer Screening has reduced mortality rate but 16-

35% Mammography is 90% sensitive technique by

not highly specific Only 1 in 7 needle biopsies performed has a

positive result for cancer Anxiety, discomfort

Needle Biopsy

(Andersson, L. Janzon, BMJ, 1988)(Linver, S. et al, Radiology, 1992) (Pisano, C. et al, NEJM, 2005)(Giotto, online, 2009)

Breast Microcalcifications Microcalcifications occur in 60% of breast lesions Maybe be benign or malignant:

Calcium hydroxyapatite in both malignant and benign

Calcium oxalate benign only

(Youk, J. et al, Radiographics, 2007)

Dual Energy- Renal Stones Dual energy CT- high and low kV exposures Attenuation changes across the energies Separation of uric, calcium hydroxyapatite and calcium oxalate renal

calculi

Dual-energy CT identifies composition of urinary stones.

Red dots: uric acid in stones. Blue dots: no uric acid.(Gould, P., online, 2009)

Dual Energy- Renal Stones Dual energy CT- high and low kV exposures Attenuation changes across the energies Separation of uric, calcium hydroxyapatite and calcium oxalate renal

calculi

8

(NIST, online, 2010)

Experiment: MARS CT of calcium

compounds

Capillary tubes of air, calcium oxalate and hydroxyapatite

MARS CT at 8 energy levels

Measured linear attenuation across the energies

Air. Ca hydrox. Ca oxalate

Image Processing Errors

Pixel

Grey scale value

Cupping Artifact

Conclusions

This experiment has established the feasibility of imaging calcium compounds on MARS-CT

Distinguishing compounds requires improving the quality of data reconstructions

If proved clinically beneficial this application could assist in distinguishing benign from malignant calcifications and reduce the number of unnecessary breast biopsies

Any questions?