Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium.
Medical Physics and Quality Assessment, Department of Imaging and Pathology, KULeuven, Leuven, Belgium.
Eur Radiol. 2022 Jul;32(7):4437-4445. doi: 10.1007/s00330-022-08584-y. Epub 2022 Mar 3.
To determine the accuracy of scoutless, fixed-dose ultra-low-dose (ULD) CT compared to standard-dose (SD) CT for pulmonary nodule detection and semi-automated nodule measurement, across different patient sizes.
Sixty-three patients underwent ULD and SD CT. Two readers examined all studies visually and with computer-aided detection (CAD). Nodules detected on SD CT were included in the reference standard by consensus and stratified into 4 categories (nodule category, NODCAT) from the Dutch-Belgian Lung Cancer Screening trial (NELSON). Effects of NODCAT and patient size on nodule detection were determined. For each nodule, volume and diameter were compared between both scans.
The reference standard comprised 173 nodules. For both readers, detection rates on ULD versus SD CT were not significantly different for NODCAT 3 and 4 nodules > 50 mm (reader 1: 93% versus 89% (p = 0.257); reader 2: 96% versus 98% (p = 0.317)). For NODCAT 1 and 2 nodules < 50 mm, detection rates on ULD versus SD CT dropped significantly (reader 1: 66% versus 80% (p = 0.023); reader 2: 77% versus 87% (p = 0.039)). Body mass index and chest circumference did not influence nodule detectability (p = 0.229 and p = 0.362, respectively). Calculated volumes and diameters were smaller on ULD CT (p < 0.0001), without altering NODCAT (84% agreement).
Scoutless ULD CT reliably detects solid lung nodules with a clinically relevant volume (> 50 mm) in lung cancer screening, irrespective of patient size. Since detection rates were lower compared to SD CT for nodules < 50 mm, its use for lung metastasis detection should be considered on a case-by-case basis.
• Detection rates of pulmonary nodules > 50 mmare not significantly different between scoutless ULD and SD CT (i.e. volumes clinically relevant in lung cancer screening based on the NELSON trial), but were different for the detection of nodules < 50 mm(i.e. volumes still potentially relevant in lung metastasis screening). • Calculated nodule volumes were on average 0.03 mL or 9% smaller on ULD CT, which is below the 20-25% interscan variability previously reported with software-based volumetry. • Even though a scoutless, fixed-dose ULD CT protocol was used (CTDI0.15 mGy), pulmonary nodule detection was not influenced by patient size.
确定无定位像、固定剂量超低剂量（ULD）CT 与标准剂量（SD）CT 在检测肺结节和半自动结节测量方面的准确性，以及在不同患者体型中的差异。
63 名患者接受了 ULD 和 SD CT 检查。两名读者分别进行了视觉和计算机辅助检测（CAD）检查。SD CT 上检测到的结节通过共识纳入参考标准，并根据荷兰-比利时肺癌筛查试验（NELSON）进行了分类（结节分类，NODCAT）。确定 NODCAT 和患者体型对结节检测的影响。对于每个结节，比较两种扫描的体积和直径。
参考标准包括 173 个结节。对于两位读者，ULD 与 SD CT 的检测率在 NODCAT 3 和 4 类结节（直径>50mm）中没有显著差异（读者 1：93%比 89%（p=0.257）；读者 2：96%比 98%（p=0.317））。对于 NODCAT 1 和 2 类结节（直径<50mm），ULD 与 SD CT 的检测率显著下降（读者 1：66%比 80%（p=0.023）；读者 2：77%比 87%（p=0.039））。体重指数和胸围均未影响结节的可检测性（p=0.229 和 p=0.362）。ULD CT 上计算的体积和直径较小（p<0.0001），但 NODCAT 无差异（84%一致）。
无定位像的 ULD CT 可可靠地检测肺癌筛查中具有临床相关体积（>50mm）的实性肺结节，与患者体型无关。由于与 SD CT 相比，<50mm 的结节检测率较低，因此应根据具体情况考虑其在肺转移检测中的应用。
在检测 NELSON 试验中基于体积具有临床意义的肺结节（>50mm）时，无定位像的 ULD 和 SD CT 的检测率没有显著差异，但在检测<50mm 的结节时（即体积仍然可能与肺转移筛查相关），检测率存在差异。
ULD CT 上计算的结节体积平均小 0.03mL 或 9%，低于以前报道的基于软件体积测量的 20-25%的两次扫描间变异。
即使使用无定位像、固定剂量的 ULD CT 方案（CTDI0.15mGy），患者体型也不会影响肺结节的检测。
