title: 99mTc-sestamibi using a direct conversion molecular breast imaging system to assess tumor response to neoadjuvant chemotherapy in women with locally advanced breast cancer.
abstract: OBJECTIVE
  The objective of this study was to determine the ability of breast imaging with 99mTc-sestamibi and a direct conversion-molecular breast imaging (MBI) system to predict early response to neoadjuvant chemotherapy (NAC).
  
  
  METHODS
  Patients undergoing NAC for breast cancer were imaged with a direct conversion-MBI system before (baseline), at 3 to 5 weeks after onset, and after completion of NAC. Tumor size and tumor-to-background (T/B) uptake ratio measured from MBI images were compared with extent of residual disease at surgery using the residual cancer burden.
  
  
  RESULTS
  Nineteen patients completed imaging and proceeded to surgical resection after NAC. Mean reduction in T/B ratio from baseline to 3 to 5 weeks for patients classified as RCB-0 (no residual disease), RCB-1 and RCB-2 combined, and RCB-3 (extensive residual disease) was 56% (SD, 0.20), 28% (SD, 0.20), and 4% (SD, 0.15), respectively. The reduction in the RCB-0 group was significantly greater than in RCB-1/2 (P = 0.036) and RCB-3 (P = 0.001) groups. The area under the receiver operator characteristic curve for determining the presence or absence of residual disease was 0.88. Using a threshold of 50% reduction in T/B ratio at 3 to 5 weeks, MBI predicted presence of residual disease at surgery with a diagnostic accuracy of 89.5% (95% confidence interval [CI], 0.64%-0.99%), sensitivity of 92.3% (95% CI, 0.74%-0.99%), and specificity of 83.3% (95% CI, 0.44%-0.99%). The reduction in tumor size at 3 to 5 weeks was not statistically different between RCB groups.
  
  
  CONCLUSIONS
  Changes in T/B ratio on MBI images performed at 3 to 5 weeks following initiation of NAC were accurate at predicting the presence or absence of residual disease at NAC completion.
authors.affiliation: From the Departments of *Radiology; †Surgery; ‡Breast Clinic, Department of Internal Medicine, Mayo Clinic, Rochester, MN; and §EPIC Imaging Center, Portland, OR.
authors.forename: David
authors.initials: D
authors.lastname: Mitchell
authors.forename: Carrie B
authors.initials: CB
authors.lastname: Hruska
authors.forename: Judy C
authors.initials: JC
authors.lastname: Boughey
authors.forename: Dietlind L
authors.initials: DL
authors.lastname: Wahner-Roedler
authors.forename: Katie N
authors.initials: KN
authors.lastname: Jones
authors.forename: Cindy
authors.initials: C
authors.lastname: Tortorelli
authors.forename: Amy Lynn
authors.initials: AL
authors.lastname: Conners
authors.forename: Michael K
authors.initials: MK
authors.lastname: O'Connor
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000000981:diagnostic imaging* / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D057054:Molecular Imaging; D020360:Neoadjuvant Therapy; D011877:Radionuclide Imaging; D017256:Technetium Tc 99m Sestamibi; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D017256:Technetium Tc 99m Sestamibi