Patient Demographics
A summary of the characteristics of the patients in the G2, G15, and G780 groups is shown in Table 1. Seventy-eight patients who underwent total-body PET/CT were included (55 men and 23 women, mean age 59.56 ± 12.74 years). Of these, 53 patients had solitary tumours and 25 had multiple tumours. Another 78 patients underwent conventional PET/CT (54 men and 24 women, mean age 58.81 ± 12.27 years). Among these patients, 57 had solitary tumours and 21 had multiple tumours. A significant difference in tumour size was found between the G2, G15, and G780 groups (P < 0.05). Intergroup differences in other characteristics were not significant (all P > 0.05).
Table 1
Demographics of patients who underwent total-body PET/CT and conventional PET/CT
Characteristic | G2/G15 | G780 | P-value |
Age (year, range) | 59.56±12.74 (21-85) | 58.81±12.27 (20-81) | 0.626 |
Sex | | | 0.861 |
Male (%) | 55 (70.5%) | 54 (69.2%) | |
Female (%) | 23 (29.5%) | 24 (30.8%) | |
Tumours | | | 0.482 |
Solitary (%) | 53 (67.9%) | 57 (73.1%) | |
Multiple (%) | 25 (32.1%) | 21 (26.9%) | |
Tumour size (cm, range) | 5.24±3.66 (1.0-25.1) | 7.02±4.57 (1.5-20.2) | 0.009⁕ |
Pathological types | | | 1.000 |
HCC II-III (%) | 36 (46.2%) | 34 (43.6%) | |
ICC II-III (%) | 24 (30.8%) | 26 (33.3%) | |
HCC-ICC II-III (%) | 5 (6.4%) | 3 (3.8%) | |
Inflammation (%) | 2 (2.6%) | 2 (2.6%) | |
Haemangioma (%) | 3 (3.8%) | 3 (3.8%) | |
EHE (%) | 1 (1.3%) | 1 (1.3%) | |
HBillN I (%) | 1 (1.3%) | 1 (1.3%) | |
SNN (%) | 2 (2.6%) | 2 (2.6%) | |
DN (%) | 2 (2.6%) | 3 (3.8%) | |
FNH (%) | 1 (1.3%) | 2 (2.6%) | |
Angiosarcoma (%) | 1 (1.3%) | 1 (1.3%) | |
HBillN I, Hepatobiliary intraepithelial neoplasia I; SNN, solitary necrotic nodule; DN, dysplastic nodule; EHE, epithelioid haemangioendothelioma; FNH, focal nodular hyperplasia |
⁕ P < 0.05 |
Lesion detectability and between G2 and G15 and TNM stages in the two groups
As shown in Table 2. A total of 87 tumours, large or small, were identified in G2 and G15, and no tumours were missed in G2. Fifty-nine lymph nodes were identified in G15, while 56 lymph nodes were identified in G2; three missed lymph nodes were located in the portal vena cava space, hepatogastric space, and cardiophrenic angle. The location of distant metastasis was the kidney in both G2 and G15. No significant difference was found in lesion detectability between G2 and G15(P > 0.05).
Table 2
Lesion detectability and TNM stage of liver cancer patients in the G2, G15, and G780 groups
| G2 | G15 | P-value (#) | G780 | P-value (‡) |
Lesion detection⁕ | | | | | |
Tumours | 87 | 87 | | / | |
Lymph nodes | 56 | 59 | 0.854 | / | |
TNM stage† | | | | | 1.000 |
Tx | 63 (95.45%) | 63 (95.45%) | | 62 (96.87%) | |
N Stage | | | 1.000 | | 0.600 |
N0 | 44 (84.62%) | 43 (82.69%) | | 44 (83.02%) | |
N1 | 10 (71.43%) | 10 (71.43%) | | 7 (63.64%) | |
M Stage | | | | | 1.000 |
M0 | 65 (98.48%) | 65 (98.48%) | | 63 (98.44%) | |
M1 | 1 (1.52%) | 1 (1.52%) | | 1 (1.56%) | |
⁕ Number of lesions |
† Number of patients |
# Comparison between the G2 and G15 groups |
‡ Comparison between the G2 and G780 groups |
Among the 87 patients with total-body PET/CT imaging data, liver cancer was confirmed by pathological examination in 66 patients, of which 14 showed lymph node metastasis. In G2 and G15, 63 liver cancer patients, with one patient showing distal metastasis, were diagnosed based on rater’s subjective experience. Ten cases of lymph node metastasis were diagnosed in G2 and G15, while 44 and 43 cases without metastasis were diagnosed in G2 and G15, respectively. The patients with liver cancer in the G2 group showed the same TNM stage as those in the G15 group (P > 0.05).
Another 78 patients underwent conventional uMI780 PET/CT scanning, of which 64 were confirmed to show liver cancer by pathological examination and 11 showed lymph node metastasis. In the G780 group, 62 liver cancer patients, including one with distal metastasis, were diagnosed by the same raters’ evaluations; of these, seven of showed lymph node metastasis and 44 did not show metastasis.
In comparisons involving G780, the TNM stage in cancer patients was not influenced by the rapid (2 min) acquisition in total-body PET/CT imaging (all P > 0.05).
Diagnostic performances of G2, G15, and G780 in the detection of liver cancer
The diagnostic performances of G2, G15, and G780 in the detection of liver cancer were shown in Table 3. Sixty-three cancer patients and nine cases with benign neoplasm were diagnosed in G2 and G15, which included three false-positive patients (one patient with hepatobiliary intraepithelial neoplasia I, HBillN I; one patient with solitary necrotic nodule, SNN; one patient with dysplastic nodule, DN), and three false-negative patients (two patients with HCC, one patient with ICC). The diagnostic performances of G2 and G15 were as follows: sensitivity, 95.45%; specificity, 75.0%; PPV, 95.45%; NPV, 75%; and diagnostic accuracy, 92.31%.
Table 3
Diagnostic performance in the G2, G15, and G780 groups
| G2 | G15 | G780 |
TP/FP | 63/3 | 63/3 | 62/5 |
TN/FN | 9/3 | 9/3 | 9/2 |
Sensitivity (n) | 95.45% (63/66) | 95.45% (63/66) | 96.88% (62/64) |
Specificity (n) | 75.00% (9/12) | 75.00% (9/12) | 64.29% (9/14) |
Accuracy (n) | 92.31% (72/78) | 92.31% (72/78) | 91.03% (71/78) |
PPV (n) | 95.45% (63/66) | 95.45% (63/66) | 92.54% (62/67) |
NPV (n) | 75% (9/12) | 75% (9/12) | 81.82% (9/11) |
TP, True positive; FP, false positive; TN, true negative; FN, false negative; PPV, positive predictive value; NPV, negative predictive value |
† Number of patients |
Among the 78 patients who underwent assessments with the uMI780 PET/CT scanner, 62 and 9 patients were diagnosed as showing malignant lesions and benign tumors, respectively, which included five false-positive cases (one patient with inflammation, one patient with SNN, two patients with focal nodular hyperplasia, FNH; one patient with HBillN I) and two false-negative cases (two patients with HCC) were detected. The diagnostic performance as follows: sensitivity, 96.88%; specificity, 64.29%; PPV, 92.54%; NPV, 81.82%; and diagnostic accuracy, 91.03%.
Quantitative analysis of benign and malignant lesions in G2, G15, and G780
The quantitative analysis of benign and malignant lesions is shown in Table 4. For both benign and malignant lesions, no significant differences were found between G2 and G15 in the tumour SUVmax, liver SUVmean, and TLR. G780 showed a lower liver SUVmean than G2 and G15 for both benign or malignant lesions (all P < 0.05), but the tumour SUVmax and TLR in G2 and G15 were equivalent to that in G780 (P > 0.05). The tumour SUVmax and TLR of malignant lesions in G2 were higher than those in benign lesions, while no significant difference was shown between them (Figure 2). The ROC curve analysis (tumour SUVmax cut-off = 4.34, TLR cut-off = 1.34) of G2 showed that the tumour SUVmax yielded AUCs of 0.812 (95% CI 0.703-0.894) with sensitivity and specificity of 75.81% and 81.80% respectively, while the TLR exhibited AUCs of 0.861 (95% CI 0.760-0.931) with sensitivity and specificity of 88.71% and 81.82%, respectively (Figure 3). However, the diagnostic performance did not differ from the tumour SUVmax and the TLR (AUCs 0.812 and 0.861; P = 0.218).
Table 4
The quantitative PET parameters of benign and malignant tumours in the G2, G15, and G780 groups
PET parameters | Benign | Malignant |
G2 | G15 | G780 | G2 | G15 | G780 |
Tumour SUVmax (g/mL) | 3.96±1.59† | 3.61±1.59† | 4.69±3.53† | 9.87±8.25 | 9.78±8.46 | 8.55±6.29 |
Liver SUVmean (g/mL) | 2.65±0.61⁕ | 2.57±0.57⁕ | 2.07±0.36 | 2.68±0.37⁕ | 2.56±0.35⁕ | 2.32±0.39 |
TLR | 1.58±0.93† | 1.50±0.93† | 2.17±1.33† | 3.75±3.24 | 3.91±3.53 | 3.72±2.68 |
SUVmax, Maximum standardized uptake value; SUVmean, mean standardized uptake value; TLR, tumour SUVmax/liver SUVmean |
⁕ Compared to the G780 group (P < 0.05) |
† Compared to malignant lesions (P < 0.05) |