Usefulness of low-dose CT in the detection of pulmonary metastasis of gestational trophoblastic tumours.
OBJECTIVE
To determine whether a low-dose spiral chest computed tomography (CT) examination could replace standard-dose chest CT in detecting pulmonary metastases in patients with gestational trophoblastic tumour (GTT).


METHODS
In a prospective investigation, 67 chest CT examinations of 39 GTT patients were undertaken. All the patients underwent CT examinations using standard-dose (150 mAs, pitch 1, standard reconstruction algorithm) and low-dose (40 mAs, pitch 2, bone reconstruction algorithm) protocols. Two radiologists interpreted images independently. A metastasis was defined as a nodule within lung parenchyma that could not be attributed to a pulmonary vessel. The number of metastases detected with each protocol was recorded. The size of each lesion was measured and categorized as <5, 5-9.9, and > or = 10 mm. Wilcoxon's signed rank test was used to assess the difference between the numbers of lesion detected by the two protocols.


RESULTS
The CT dose index (CTDI) for the standard-dose and low-dose CT protocols was 10.4 mGy and 1.4 mGy, respectively. One thousand, six hundred, and eighty-two metastases were detected by standard-dose CT, and 1460 lesions by the low-dose protocol. The numbers detected by low-dose CT were significantly less than those detected by standard-dose CT (Z=-3.776, p<0.001), especially for nodules smaller than 5mm (Z=-4.167, p<0.001). However, the disease staging and risk score of the patients were not affected by use of the low-dose protocol.


CONCLUSIONS
Low-dose chest CT can be used as a staging and follow-up procedure for patients with GTT.
Xu
X J
XJ
Department of Radiology, First Affiliated Hospital, Woman Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
Lou
F L
FL
Zhang
M M
MM
Pan
Z M
ZM
Zhang
L
L
D000328:Adult; D004307:Dose-Response Relationship, Radiation; D005260:Female; D031901:Gestational Trophoblastic Disease / Q000000981:diagnostic imaging* / Q000556:secondary; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D008875:Middle Aged; D011247:Pregnancy; D011446:Prospective Studies; D036542:Tomography, Spiral Computed; D014594:Uterine Neoplasms