Diagnostic Value of PET/CT in Metastatic Liver Cancer

Fig. 9.1

The PET/CT image of colorectal cancer liver metastases (colonic lesions, red arrows; liver metastases, white arrows). Coronal plane, sagittal plane, cross section, planar section

Fig. 9.2

Male patient, age 43. Liver metastases were detected 3 months after colorectal cancer surgery (liver metastases: red arrows). Coronal plane, sagittal plane, cross section, planar section

Fig. 9.3

Recurrent lesions were detected 6 months after colorectal cancer surgery, and the liver metastases had grown bigger (recurrent lesions, white arrows; liver metastases, red arrows). Sagittal plane, cross section, cross section, planar section

Table 9.1

Comparisons of the diagnostic value of PET, PET/CT, and MRI for colon cancer liver metastases

	PET	PET/CT	MRI
Accuracy (in %)	79	92	91
Sensitivity (in %)	61	84	73
Specificity (in %)	98	100	100
PPV (in %)	98	100	100
NPV (in %)	70	86	88

The overall diagnosis of extrahepatic metastases of colorectal cancer remains unresolved. The sensitivity and accuracy of CT for diagnosing liver metastases are high, but CT is not ideal for diagnosing extrahepatic metastasis, especially abdominal lymph node metastases, which can usually only be diagnosed according to the size of the lymph nodes: Enlarged lymph nodes (larger than 1 cm) are considered to be metastases; however, many are enlarged because of chronic inflammation. Furthermore, metastases of smaller lymph nodes are mistaken for normal lymph nodes. PET identifies metastases according to the metabolic activity of the lymph nodes, which is a more accurate indicator than size. Research has shown that the sensitivity of PET for detecting nonlocal recurrence of extrahepatic metastases is 94 %, while that of CT is only 67 %; PET and CT have similar specificity of 98 % and 96 %, respectively [4].

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