Jagruti Shah MD, Presenter: Nothing to Disclose

Emily F. Conant MD, Abstract Co-Author: Research grant, General Electric Company

Mark Alan Rosen MD, PhD, Abstract Co-Author: Nothing to Disclose

Mitchell Dennis Schnall MD, PhD, Abstract Co-Author: Research funded, Siemens Consultant, General Electric Company

Chaitanya Divgi MD, Abstract Co-Author: Nothing to Disclose

To determine why some breast cancers are not visualized on whole body FDG-PET.

209 patients with core biopsy or FNA proven breast cancer were recruited to an IRB approved multimodality imaging protocol. All patients were imaged with digital mammography (DM), whole breast ultrasound (US), contrast enhanced MR (CEMR) and whole body FDG-PET (PET). Four imagers rendered interpretations blinded to the results of the other modalities (except for the US reader who also interpreted the entry mammogram). Cases were excluded if the index cancer was not detected by any modality. The detection rate, histology, and size of the breast cancers were compared across modalities. Studies where cancers were not detected by PET were retrospectively evaluated to determine the reason for the lack of visualization.

Of the 209 cases, 205 had the index cancer detected by at least one imaging modality. Of these 205, 163 cancers were detected by PET and 42 were not. Of the 42 PET non-visualized cancers, 19 were detected by all other modalities, 14 were detected by 2 other modalities and 9 cases were detected by only 1 other modality. Of the 42 cases, 10 were DCIS (sizes from 0.4-2.5 cm) and 32 were invasive cancers (sizes from 1.0-3.2 cm: 24 ductal, 3 lobular, 5 not otherwise specified-NOS). Of the 32 invasive cancers, 10 were less than 1 cm and 22 were larger than 1 cm. Of the 22 cancers larger than 1 cm, 14 were invasive ductal, 5 were NOS and 3 were invasive lobular cancers. Of the 22 invasive cancers larger than 1 cm and not detected by PET, 9 cases (5 ductal, 3 NOS and 1 lobular) had either diffuse or patchy uptake in the breasts (7 bilateral and 2 affected breast only), causing increased background activity making tumor visualization difficult.

In our series, the sensitivity of FDG-PET for the detection of primary breast carcinoma is 80%. Many features contribute to the decreased sensitivity, including size, histology and tracer uptake in surrounding breast tissue. FDG-PET is therefore not a sensitve imaging modality for evaluation of some primary breast tumors.

FDG-PET may not be the ideal imaging modality for detection of some primary breast tumors.

Shah, J, Conant, E, Rosen, M, Schnall, M, Divgi, C, Breast Cancers That Are Not Detected by FDG-PET: Why Can’t We See Them?.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5011186.html