Liver metastases : what the radiologist needs to know, W Schima скачать в хорошем качестве

Liver metastases : what the radiologist needs to know, W Schima

https://www.icimagingsociety.org.uk/ Wolfgang Schima Department of Diagnostic and Interventional Radiology, Goettlicher Heiland Krankenhaus, Barmherzige Schwestern Krankenhaus, and Sankt Josef Krankenhaus, Vinzenzgruppe, Vienna, Austria Liver metastases are much more common than primary malignant tumours of the liver. The diagnosis is based on imaging findings (and biopsy). Radiology plays a key role in the management of patients with suspected liver metastases by detecting or excluding liver metastases. Ultrasound is widely available, but it has limitations in the detection of metastases due to operator and patient dependence, and contrast-enhanced ultrasound (CEUS) is not performed for metastasis detection on a routine basis. The standard imaging technique for staging in patients with extrahepatic neoplasms at high risk for developing liver metastases (i.e., colo-rectal, gastric, oesophageal, pancreatic cancer, etc.) is contrast-enhanced MDCT, with a reported sensitivity of 63–79% [1,2]. Examination protocol is key to the diagnosis. An unenhanced scan is not routinely necessary, because it very rarely contributes to lesion detection [3]. For detection and characterization a bi-phasic (later arterial and venous phases) contrast-enhanced protocol is recommended, after IV administration of 0.5–0.6 g of iodine per kg b.w. (= 1.7–2 ml contrast material @ 300 mg/ml) at a flow rate of 4–5 ml/s. With current modulation techniques, lowering of kVp (80 or 100 kVp instead of 120 kVp) is possible of patients at lower body weight. This allows further reduction of contrast material. Reconstruction of thin, overlapping slices of 2.5-3 mm for viewing is superior to a slice thickness of 5 mm or more. In case of equivocal MDCT (e. g., in patients with moderate to severe liver steatosis) [4,5] or in patients with colo-rectal cancer and potentially resectable liver metastases, MRI should be performed. The standard MRI protocol includes single breath-hold T1w GRE in- and opposed-phase, diffusion-weighted imaging (DWI), T2w TSE and contrast-enhanced pulse sequences. In clinical practice, MRI with liver-specific contrast agent (gadoxetic acid, Bayer Healthcare, Germany) is not only superior to contrast-enhanced MDCT, but also to MRI with non-specific gadolinium chelates, although is there is very little evidence in the literature. A recent meta-analysis showed that MRI with DWI and liver-specific contrast agent combined is superior to DWI or contrast-enhanced MRI alone (sensitivity 96% vs. 91% and 87%, respectively) [6]. Contrast-enhanced MDCT is used to monitor therapy response or disease progression. According to RECIST 1.1, uni-dimensional measurement of a maximum of 2 target lesions per organ (and a total of up to 5 lesions) defines tumour response. To eliminate inaccurate tumour measurements due to volume averaging, target lesions must have a minimum size of 1 cm. Complete response (CR) is defined by complete tumour disappearance, partial response (PR) by ≥30% decrease of the sum of all the longest diameters of all target lesions in comparison to baseline. Progressive disease (PD) is defined by an increase of 20% of longest diameters of target lesions in comparison to nadir, with stable disease (SD) representing tumour response not falling into one of the 2 categories. If patients with previously considered non-resectable metastatic disease turn potentially resectable due to overwhelming chemotherapy response, then CE-MRI should be performed to localise residual metastases for further planning [7]. In summary, MDCT examination protocol should be optimized for detection and characterization of focal liver lesions, considered the radiation dose in patient populations undergoing repeated scanning. MDCT is the standard technique for assessment of liver metastases and for follow-up after chemotherapy. Contrast-enhanced MRI including DWI and liver-specific agents is the modality of choice in patients with equivocal MDCT or in patients with CRC and potentially resectable liver metastases. References https://cancerimagingjournal.biomedce...