MacDonald Lawrence R, Hippe Daniel S, Bender Leila C, Cotter Elizabeth W, Voria Pooja R, Hallam Paula S, Wang Carolyn L, Haseley David R, Kelly Mary M, Parikh Jay R, Beatty J David, Rogers James V
Radiology Department, University of Washington, Seattle, Washington; and
Radiology Department, University of Washington, Seattle, Washington; and.
J Nucl Med. 2016 Mar;57(3):348-54. doi: 10.2967/jnumed.115.165787. Epub 2015 Dec 3.
We studied the effects of reduced (18)F-FDG injection activity on interpretation of positron emission mammography (PEM) images and compared image interpretation between 2 postinjection imaging times.
We performed a receiver-operating-characteristic (ROC) study using PEM images reconstructed with different count levels expected from injected activities between 23 and 185 MBq. Thirty patients received 2 PEM scans at postinjection times of 60 and 120 min. Half of the patients were scanned with a standard protocol; the others received one-half of the standard activity. Images were reconstructed using 100%, 50%, and 25% of the total counts acquired. Eight radiologists used a 5-point confidence scale to score 232 PEM images for the presence of up to 3 malignant lesions. Paired images were analyzed with conditional logistic regression and ROC analysis to investigate changes in interpretation.
There was a trend for increasing lesion detection sensitivity with increased image counts: odds ratios were 2.2 (P = 0.01) and 1.9 (P = 0.04) per doubling of image counts for 60- and 120-min uptake images, respectively, without significant difference between time points (P = 0.7). The area under the ROC curve (AUC) was highest for the 100%-count, 60-min images (0.83 vs. 0.75 for 50%-counts, P = 0.02). The 120-min images had a similar trend but did not reach statistical significance (AUC = 0.79 vs. 0.73, P = 0.1). Our data did not yield significant trends between specificity and image counts. Lesion-to-background ratios increased between 60- and 120-min scans (P < 0.001).
Reducing the image counts relative to the standard protocol decreased diagnostic accuracy. The increase in lesion-to-background ratio between 60- and 120-min uptake times was not enough to improve detection sensitivity in this study, perhaps in part due to fewer counts in the later scan.
我们研究了减少（18）F-FDG注射活度对正电子发射乳腺断层摄影（PEM）图像解读的影响，并比较了注射后两个成像时间点的图像解读情况。
我们进行了一项接受者操作特征（ROC）研究，使用了根据23至185 MBq之间的注射活度预期的不同计数水平重建的PEM图像。30名患者在注射后60分钟和120分钟接受了两次PEM扫描。一半患者按照标准方案进行扫描；另一半接受标准活度的一半。使用采集到的总计数的100%、50%和25%重建图像。8名放射科医生使用5分置信度量表对232张PEM图像中多达3个恶性病变的存在情况进行评分。通过条件逻辑回归和ROC分析对配对图像进行分析，以研究解读的变化。
随着图像计数增加，病变检测灵敏度有增加趋势：对于60分钟和120分钟摄取图像，图像计数每增加一倍，优势比分别为2.2（P = 0.01）和1.9（P = 0.04），时间点之间无显著差异（P = 0.7）。对于100%计数的60分钟图像，ROC曲线下面积（AUC）最高（50%计数时为0.83对0.75，P = 0.02）。120分钟图像有类似趋势但未达到统计学显著性（AUC = 0.79对0.73，P = 0.1）。我们的数据在特异性和图像计数之间未产生显著趋势。60分钟和120分钟扫描之间病变与背景比值增加（P < 0.001）。
相对于标准方案减少图像计数会降低诊断准确性。在本研究中，60分钟和120分钟摄取时间之间病变与背景比值的增加不足以提高检测灵敏度，可能部分原因是后期扫描计数较少。
