Role of dual-energy contrast-enhanced digital mammography as a problem-solving tool in dense breasts: A case report
A 55 year-old lady who complained of occasional heaviness in the left chest was referred to us from cardiac OPD. As she required no active cardiologic intervention, a screening mammogram was undertaken as a part of routine health check-up. There was no family history of any breast or gynecological malignancy and no prior breast imaging had been undertaken. Digital mammograms in both craniocaudal [] and mediolateral [] views were taken on a GE Senographe Essential and viewed on an IDI work station. Both breasts were extremely dense (>90%) with no definite area of mass lesion being noted. Few prominent left axillary lymph nodes were noted. Benign scattered calcifications were noted bilaterally with no evidence of microcalcifications. Clinically, both breasts had an irregular lumpy feel on palpation. On USG, a suspicious hypoechoic area was noted within the dense glandular tissue of left breast with evidence of intralesional vascularity. Two enlarged left axillary nodes were noted measuring 2.5-2.7 cm each, with preserved hilar architecture. Screening of right breast appeared unremarkable. In view of dense mammogram and suspicious USG findings, the patient underwent a dual-energy CEDM. Baseline renal function of the patient was evaluated prior to contrast injection. Institutional review board approval and informed patient consent was obtained. Approximately 70 ml (at 1.5 ml/kg) of non-ionic contrast medium (Iomeron 350 mg/ml) was loaded into a Liebel-Flarsheim pressure injector. The rate was set at 3 ml/sec. The right (contralateral) antecubital vein was punctured and connected to the injector. A stopwatch on the console set at 0 sec was started simultaneously with initiation of contrast injection. The radiographer had a time gap of approximately 90 sec after cessation of contrast injection for positioning the patient for the right craniocaudal (RCC) view. This was taken at the 2nd minute. The left craniocaudal (LCC), right mediolateral (RMLO) and left mediolateral (LMLO) views were taken at 3rd, 4th, and 5th minute since start of the contrast, respectively. All images were acquired well within the 7-min cut-off as recommended by the manufacturer and as noted in various clinical studies.[] Approximately 10 daN compression was applied for each exposure. All views were obtained using dual energy where the low-energy exposure was acquired using a Mo/Rh target/filter combination with tube voltages (kVp) ranging from 26 to 30 kVp. The high-energy images were acquired using Mo/Cu target/filter combination and with tube voltages in the range of 45-49 kVp. Within approximately 5 sec, a recombination algorithm, using the low-energy, high-energy X-ray spectra and the thickness of compressed breast produced dual-energy subtracted images which highlighted the iodine-enhanced areas. A small enhancing nodule was noted in the right breast centrally while a mass-like enhancement was noted in left breast lower inner quadrant in the respective CC views []. While the right breast lesion was no longer visualized, the left lesion was only subtly imaged in the respective MLO views, suggesting a probable rapid washout []. The enhancing left breast mass corresponded to the suspicious area noted on USG, while the focal nodular enhancement on the right corresponded to an isoechoic lesion which was completely missed on the initial scan. Both lesions were biopsied under ultrasound guidance in the same sitting. Histopathological evaluation revealed the right breast nodule to be a grade 1 and the left breast mass to be a grade 3 invasive ductal carcinoma. The patient preferred to pursue metastatic work-up and further treatment at her hometown.