Count density measured in patients who had both standard MBI (performed with a 740 MBq injection, standard collimation, and standard energy window) and low-dose MBI (performed with either 148 or 296 MBq injection, optimized collimation, and wide energy window). Count density (counts/cm2) is expressed per 10 min acquisition per MBq.
Example views from four patients undergoing both standard MBI and low-dose screening MBI with approximately 2–3 yr between exams. On the top row, standard 10 min/view MBI was performed with a 740 MBq injection, standard collimator, and standard energy window. On the bottom row, low-dose 10 min/view MBI was performed using either 148 or 296 MBq injection, optimized collimation, and wide energy window. All images were interpreted as negative.
A patient with multifocal invasive lobular cancer and nipple adenoma. MBI was performed following 296 MBq injection Tc-99 m sestamibi and with the wide energy window using the standard collimation [shown in (a)] and the optimized collimation [shown in (b)]. Count density was improved by a factor of 2.4 with the optimized collimation.
MBI study acquired for 10 min following 740 MBq injection Tc-99 m sestamibi, using standard collimation, and (a) wide energy window (110–154 keV), (b) standard energy window (126–154 keV). The difference of images in panels (a) and (b) is shown in panel (c). Each image is displayed on the range from its individual minimum to maximum count. Count density in this patient was improved by a factor of 2.6 with the wider energy window, A 1.3 cm × 1.0 cm × 0.9 cm invasive ductal carcinoma was detected, and the wide energy window resulted in improved detection of an extension of ductal carcinoma in situ (see arrow).
In this patient with a 0.8 cm tubular carcinoma, low-dose MBI was performed with 296 MBq injection Tc-99 m sestamibi and acquired in eight dynamic frames. Images representing acquisition durations of 2.5, 5, 7.5, and 10 min/breast view were simulated by summing counts from either two, four, six, or eight frames, respectively. Images were acquired with optimized collimation and wide energy window. The average final assessment and individual assessments from four readers are provided, where an assessment of 3 or higher is considered positive.
The count density (counts/cm2 in a 1.25 min frame) measured in 19 MBI clinical studies as a function of time postinjection of 296 MBq Tc-99 m sestamibi. Studies were performed with optimized collimation and wide energy window. The patient with the median count density is highlighted in bold.
Results from lesion detection study in which 4 readers interpreted MBI studies from 32 patients with 64 breasts, comprising 8 breasts with breast cancer and 12 breasts with benign lesions. MBI was acquired with 296 MBq injection Tc-99 m sestamibi, and acquisition durations of 2.5–10 min/view.
Article metrics loading...
Full text loading...