Table 1
Locations of pathologic FDG uptake
| Sites of abnormal FDG uptake | n |
|---|---|
| Anostomosis line (area) | 7 |
| Rectum | 9 |
| Rectosigmoid region | 11 |
| Liver | 9 |
| Caecum | 1 |
| Kidney | 1 |
| Abdominal mass | 4 |
| Presacral mass | 5 |
| Sigmoid region | 3 |
| Descending colon | 2 |
| Lung | 1 |
Table 2
18F-FDG-PET/CT results, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) according to final histopathologic diagnosis
| Histopathologic diagnosis | 18F-FDG-PET/CT Results | ||||||
|---|---|---|---|---|---|---|---|
| Positive | Negative | Sensitivity | Specificity | PPV | NPV | Total (n) | |
| Malignant | TP = 24 | FN = 0 | 24 | ||||
| Benign | FP = 14 | TN = 15 | 29 | ||||
| Total (n) | 38 | 15 | 100% | 51.7% | 63.1% | 100% | 53 |
[i] FN = False negative; FP = False positive; TN = True negative; TP = True positive
Table 3
FDG-PET/CT findings according to serum Ca 19-9 or CEA levels for histopathologically proven recurrence
| 18F-FDG-PET/CT results | |||
|---|---|---|---|
| Ca 19-9 or CEA levels | True positive | True negative | Total (n) |
| Elevated | 9 | 1 | 10 |
| Normal | 13 | 14 | 27 |
| Total (n) | 22 | 15 | 37 |
Table 4
Overlap between 18F-FDG-PET/CT findings and conventional imaging modalities (CT or MRI) in histopathologically proven recurrence
| 18F-FDG-PET/CT results | |||
|---|---|---|---|
| CT/MRI | True positive | True negative | Total (n) |
| Malign | n | 6 | 17 |
Figure 1
Box-plot graph illustrating the distribution of SUVmax through benign conditions and disease recurrence.
Figure 2
ROC curve drawn to indicate the detection and diagnostic accuracy of SUVmax in recurrence/metastasis.
Figure 3
A female patient aged 51 years with rectum cancer was operated and treated by chemoradiotherapy. MRI findings revealed suspected metastasis with serum CEA and Ca 19-9 in normal range during the follow-up. Her axial PET (A), CT (B), fusion (C) and coronal PET (D), CT (E), fusion (F) images on 18F-FDG-PET/CT showed a focal uptake in sigmoid colon with a SUVmax of 13.7 and TLG of 272 accompanied by wall thickening causing a mass lesion on CT component (arrows). Histopathology established the diagnosis as recurrence.
Figure 4
A female patient aged 73 years with sigmoid colon cancer was operated and treated by chemoradiotherapy. Her serum CEA level was 3.2 ng/ml, and Ca 19-9 was 7.3 U/ml. In the evaluation of treatment response; axial PET (A), CT (B), fusion (C) and coronal PET (D), fusion (E) images on 18F-FDG-PET/CT exhibited a diffuse uptake in sigmoid colon with a SUVmax of 10.1 and TLG of 154 accompanied by wall thickening on CT component (arrows). This uptake raised the suspicion of a probable recurrence, but histopathology confirmed it as benign.