Perfusion CT imaging of the liver: review of clinical applications

Abstract

Perfusion computed tomography (CT) has a great potential for determining hepatic and portal blood flow; it offers the advantages of quantitative determination of lesion hemodynamics, distinguishing malignant and benign processes, as well as providing morphological data. Many studies have reported the use of this method in the assessment of hepatic tumors, hepatic fibrosis associated with chronic liver disease, treatment response following radiotherapy and chemotherapy, and hepatic perfusion changes after radiological or surgical interventions. The main goal of liver perfusion imaging is to improve the accuracy in the characterization of liver disorders. In this study, we reviewed the clinical application of perfusion CT in various hepatic diseases. The advent of multidetector CT has given rise to the acquisition of images with higher quality and accuracy. Multidetector CT has been developed as a noninvasive imaging modality for evaluation of vascular anatomy. It has also made it possible to perform CT angiography of the hepatic vessels. New generation CT systems with multidetector are capable of performing volumetric imaging. These systems provide a single rotational acquisition and almost the whole upper abdomen can be appraised by means of serial rotational acquisitions at a single location in the z-direction. Multidetector CT imaging is used extensively for the preoperative selection of living related liver donors, as well as evaluation of the vascular anatomy of the recipients (1). This imaging technique is also used for the initial evaluation and follow-up of most patients with hepatic metastases, providing valuable information about the number, size, and distribution of hepatic metastases and the presence and extent of extrahepatic disease (1).Perfusion CT imaging permits the qualitative and quantitative assessment of liver perfusion. In perfusion CT, a quantitative tissue perfusion map is obtained from dynamic CT data and displayed using a color scale permitting the quantification of tissue perfusion in absolute units at high spatial resolution (2). Perfusion CT efficiently locates abnormal tissue perfusion which is difficult to detect accurately with conventional CT (3). Functional assessment of the perfusion of normal and pathologic tissues is performed by means of quantitative or semiquantitative parameters, such as blood flow (BF), blood volume (BV), mean transit time (MTT), portal liver perfusion (PLP), arterial liver perfusion (ALP) and hepatic perfusion index (HPI). Perfusion CT measures the temporal changes in tissue density through a series of dynamically acquired CT images after intravenous injection of an iodinated contrast material (4, 5). Perfusion CT may be performed quickly and provide valuable data for diagnosis. However, there are some limitations of this method such as long breath-holding for portal flow measurement, separation of arterial and portal blood flow, additional radiation exposure, limited craniocaudal scan range, and standardization of analytic methods (2). In this a...

Multimodality imaging in diagnosis and management of alveolar echinococcosis: an update

“…After all, these findings are all considered to be a reflection of the presence of periparasitic granulomatous tissue, which is detected as increased metabolic activity on PET-CT. Perfusion CT imaging may be useful in distinguishing AE from malignancies in difficult-to-diagnose hepatic AE cases. Furthermore, this modality can also be used for monitoring treatment response (29).…”

Imaging of Cholangiocarcinoma

“…Functional imaging of volume perfusion CT (VPCT) can help to assess the exact vascularization of the tumour in CC. Compared with the normal parenchyma, CC usually shows increased hepatic arterial perfusion, increased blood volume, and decreased portal perfusion [43,44]. Due to novel treatment regimens such as anti-angiogenetic drugs or targeted therapies, VPCT might be a helpful monitoring tool for judging treatment response by revealing changes in tumour vascularization in the absence of significant changes in tumour size [18].…”

Quantitative liver tumor blood volume measurements by a C-arm CT post-processing software before and after hepatic arterial embolization therapy: comparison with MDCT perfusion

“…With this method, any therapy that is planned to be given on the angio table with a capability of C-arm CT, may be individualized according to the extent of tumor perfusion (13). However, further studies are warranted to understand the detailed role of tumor to normal liver BV ratios and the possible target perfusion decreases to be achieved by any hepatic arterial embolization method.…”