Effects of TIPS on liver perfusion measured by dynamic CT

OBJECTIVE: Our aim was to measure the arterial, portal venous, and total perfusion of the liver parenchyma with dynamic, single-section CT in patients with liver cirrhosis before and after transjugular intrahepatic portosystemic shunt (TIPS) placement and to compare the results with normal values. SUBJECTS AND METHODS: Perfusion of the liver parenchyma was measured in 24 healthy volunteers and 41 patients with liver cirrhosis using dynamic single-section CT. Seventeen patients underwent TIPS placement, and CT measurements were repeated within 7 days. CT scans were obtained at a single level comprising the liver, spleen, aorta, and portal vein. Scans were obtained over a period of 88 sec (one baseline scan followed by 16 scans every 2 sec and eight scans every 7 sec) beginning with the injection of a contrast agent bolus (40 mL at 10 mL/sec). Parenchymal and vascular contrast enhancement was measured with regions of interest, and time-density curves were obtained. These data were processed with a pharmaco-dynamic fitting program (TopFit), and the arterial and portal venous component and the total perfusion of the hepatic parenchyma were calculated (milliliters of perfusion per minute per 100 mL of tissue). RESULTS: Mean normal values for hepatic arterial, portal venous, and total perfusion were 20, 102, and 122 mL/min per 100 mL, respectively. In patients with cirrhosis before TIPS, mean hepatic arterial, portal venous, and total perfusion was 28, 63, and 91 mL/min per 100 mL, respectively, which was statistically significant for all values (p <0.05). After TIPS, hepatic perfusion increased to a mean value of 48, 65, 113 mL/min per 100 mL for arterial (p <0.01), portal venous, and total (p=0.011) perfusion, respectively. CONCLUSION: In patients with cirrhosis, the hepatic arterial perfusion increased, whereas portal venous and total perfusion decreased compared with that of healthy volunteers. TIPS placement caused a statistically significant increase of the hepatic arterial and total hepatic perfusion. The portal venous parenchymal perfusion remained unchanged.     

Dynamic CT of hepatic abscesses: significance of transient segmental enhancement

OBJECTIVE: The purpose of this study was to evaluate dynamic CT findings of hepatic abscesses, especially segmental hepatic enhancement, and to clarify the cause. MATERIALS AND METHODS: Twenty-four abscesses in eight patients were examined by early (30 sec) and late phase (90 sec) dynamic CT. Patients underwent abscess drainage (n = 1), hepatic resection (n = 2), or antibiotic therapy (n = 5). CT during arterial portography and CT during hepatic arteriography were performed in one patient. We retrospectively observed the frequency and changes of segmental hepatic enhancement on dynamic CT and determined its cause using radiologic and pathologic correlation. RESULTS: Sixteen abscesses (67%) showed transient segmental hepatic enhancement and three abscesses showed only segmental hepatic enhancement in the early phase. Four abscesses in one patient who underwent CT during arterial portography and CT during hepatic arteriography showed a segmental perfusion defect on CT during arterial portography and segmental enhancement on CT during hepatic arteriography. On follow-up dynamic CT performed 10-17 days after the initial CT, segmental hepatic enhancement surrounding hepatic abscesses decreased or disappeared in all abscesses. Pathologic examination of two patients showed marked inflammatory cell infiltration with stenosis of portal venules within the portal tracts surrounding hepatic abscesses without definite inflammation in the liver parenchyma. CONCLUSION: Segmental hepatic enhancement on dynamic CT is frequently associated with hepatic abscesses and may be caused by decreased portal flow resulting from inflammation of the portal tracts.     

Hepatic perfusion CT imaging analyzed by the dual-input one-compartment model

AIM: To improve liver-perfusion imaging by using the dual-input one-compartmental model. METHODS: Single-level dynamic computed tomography (dynamic CT) was taken at the height of the hepatic hilum after a rapid intravenous injection using 40 ml of iodinated contrast material. From the time-density curve of each pixel on CT, we calculated blood-flow rate constants of liver inflow and outflow. For inflow, two constants were calculated at arterial and portal veins. We postulated that blood flow between hepatic vessels and the hepatic parenchyma could be analyzed by using the calculated constants, and made equations for liver perfusion mapping. The perfusion images obtained by this method were compared with those made by the maximum slope method. RESULTS: We applied the method to a patient with hepatolithiasis. On dynamic CT, there was an abnormal enhancement pattern in the posterior segment of the liver. Perfusion CT images made by the dual-input one-compartment model demonstrated abnormal portal perfusion of the liver. In contrast, those made by the maximum-slope method did not represent the perfusion pattern well. CONCLUSION: The dual-input one-compartmental model makes it possible to obtain more detailed information on liver hemodynamics.     

Segmental hyperattenuation in the liver as a result of right hepatic vein thrombosis: an unusual complication of central venous catheterization

Liver perfusion disorder secondary to hepatic vein occlusion is not often reported. This abnormality might be caused by invasion of the hepatic veins by tumour or compression by a large right adrenal mass. We present an unusual cause of hepatic perfusion disturbance due to right hepatic vein thrombosis resulting from inadvertent hepatic venous catheterization. On contrast-enhanced CT, the tip of a central venous catheter extended into the right hepatic vein, which was thrombosed. A sharply marginated wedge-shaped hyperdense region was demonstrated in the right lobe of the liver, thought to represent a compensatory increase in arterial flow to the affected territory.     

Hepatic haemodynamics: interrelationships between contrast enhancement and perfusion on CT and Doppler perfusion indices.

This study compares three techniques that evaluate hepatic haemodynamics for the detection of metastatic liver disease to determine the interrelationships between the techniques and to assess their equivalence. The three techniques studied were dedicated CT measurements of hepatic enhancement, CT measurements of perfusion and Doppler perfusion indices. 53 patients with proven malignancies of either breast or colon underwent a single location dynamic CT for measurement of hepatic perfusion and enhancement, whilst a subset of 12 patients underwent both CT perfusion and Doppler perfusion studies. Statistically significant correlations were found between CT arterial phase enhancement and CT arterial perfusion (r=0.612, p<0.001), and between both of these parameters and Doppler arterial flow (r=0.867, p<0.001 and r=0.842, p<0.001, respectively). Significant correlations were also found between both the ratio of CT arterial enhancement to peak enhancement and the CT arterial perfusion with the Doppler perfusion index (r=0.797, p=0.002 and r=0.725, p=0.008, respectively). Combined CT arterial and portal perfusion correlated with peak liver enhancement (r=0.614, p< 0.001), but Doppler measurements of portal flow did not correlate with any CT parameter. Increased arterial enhancement, perfusion or flow are valuable additional radiological signs for the presence of hepatic metastases that can be elicited by incorporating any one of these methods into existing imaging protocols.     

兔肝缺血再灌注损伤CT灌注及其病理对照

目的：探索CT灌注成像在兔肝脏缺血再灌注损伤（I/R）模型中的应用。方法：新西兰大白兔随机分成4组（正常对照组及I/R 6h、12h、24h组,每组5只）。I/R模型采用无创性动脉夹结扎肝左叶血供60min后,恢复血供。各组分别采用iCT行全肝灌注成像;在灌注图上测量肝动脉灌注量（HAP）、门静脉灌注量（HPP）、总灌注量（TLP）及肝动脉灌注指数（HPI）;同时行组织病理学检查。结果：与正常组对比,24h组HAP显著下降（P〈0.01）;各I/R组中HPP、TLP明显低于正常组（P〈0.05）;而在I/R 6h、12h组中,HPI显著高于对照组（P〈0.05）。镜下表现肝窦红细胞淤积,肝细胞核固缩凋亡,肝窦解离,在24h组出现局灶性坏死。结论：CT灌注成像能够动态准确反应肝I/R后微循环灌注量的变化情况。     

Hepatic metastases: the value of quantitative assessment of contrast enhancement on computed tomography

Objective: Occult and overt hepatic metastases have been the target of research in an effort to improve detection and characterisation of cancer spread and, consequently, guidance of treatment. This paper aims to illustrate the value of two quantitative techniques for assessing contrast enhancement during CT in the detection of hepatic metastases. It outlines the applications to which they can be put, and the ease of incorporation into current protocols. Methods and material: The first technique, perfusion CT, uses a single location dynamic CT sequence to obtain time–attenuation data whilst a short, high concentration IV bolus of contrast passes through the abdominal vasculature. Quantitative hepatic arterial and portal values are calculated, along with a perfusion image map. The second technique uses densitometric analysis during a modified contrast enhanced dual-phase liver CT examination. Semi-quantitative values are calculated from the images obtained at the 25 and 40 s times. Results: Both perfusion CT and densitometric analysis have been to shown to differentiate between normal and tumour-bearing liver as defined by structural CT. Hepatic metastases are associated with increased arterial perfusion and arterial phase enhancement. Increased arterial phase enhancement on densitometric analysis in the absence of overt lesions heralds the onset of visible metastases in the liver in the ensuing 18 months. Perfusion CT has also demonstrated a correlation between high arterial perfusion around a visible metastasis and increased survival. Conclusion: Both techniques can provide more information than is available from conventional enhanced CT scans alone. An algorithm for the clinical application of perfusion CT is proposed. The ease with which these quantitative techniques can be performed and the extra information they provide could lead to improved staging of cancer and more appropriate patient management.     

Evaluation of neovascularization with spectral computed tomography in a rabbit VX2 liver model: a comparison with real-time contrast-enhanced ultrasound and molecular biological findings

Objective:

To validate the feasibility of using the parameters of spectral CT and CT perfusion and the dynamic features of real-time contrast-enhanced ultrasound (CEUS) to evaluate the vascularization of VX2 hepatic tumours.

Methods:

Spectral CT imaging, CT perfusion and CEUS analysis were performed on rabbits implanted with VX2 hepatic tumours, 7 and 14 days after implantation. The perfusion parameters of CT, normalized iodine concentration (NIC) and dynamic features of CEUS were measured in the rim of the tumour (TR) and the normal liver region. The expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) was also determined.

Results:

Increased perfusion parameters of CT were found in the TR. In addition, the NIC was elevated in TR during the arterial phase, and the peak intensity of the CEUS of the TR was reached significantly earlier than that on normal liver region. At 14 days, the perfusion parameters of CT (blood volume, permeability surface and hepatic arterial fraction) offered higher accuracy and stability in differentiating the TR from the normal liver region. Furthermore, CEUS was more accurate in diagnosing tumours <1.0 cm in diameter. In addition, VEGF and FGF2 expression was higher in the TR and were positively correlated with CT and CEUS parameters, except mean transit time, rise time, washout time and peak time.

Conclusion:

Use of spectral CT with perfusion techniques, iodine-based material-decomposition analysis and dynamic CEUS changes may reflect the angiogenesis and haemodynamic information of hepatic tumours.

Advances in knowledge:

It is feasible to assess vascularization in hepatic cancer using CT or CEUS.     

CT perfusion of the liver during selective hepatic arteriography: pure arterial blood perfusion of liver tumor and parenchyma

PURPOSE: To quantify pure arterial blood perfusion of liver tumor and parenchyma by using CT perfusion during selective hepatic arteriography. METHODS: A total of 44 patients underwent liver CT perfusion study by injection of contrast medium via the hepatic artery. CT-perfusion parameters including arterial blood flow, arterial blood volume, and arterial mean transit time in the liver parenchyma and liver tumor were calculated using the deconvolution method. The CT-perfusion parameters and vascularity of the tumor were compared. RESULTS: A complete analysis could be performed in 36 of the 44 patients. For liver tumor and liver parenchyma, respectively, arterial blood flow was 184.6 +/- 132.7 and 41.0 +/- 27.0 ml/min/ 100 g, arterial blood volume was 19.4 +/- 14.6 and 4.8 +/- 4.2 ml/100 g, and arterial mean transit time was 8.9 +/- 4.2 and 10.2 +/- 5.3 sec. Arterial blood flow and arterial blood volume correlated significantly with the vascularity of the tumor; however no correlation was detected between arterial mean transit time and the vascularity of the tumor. CONCLUSION: This technique could be used to quantify pure hepatic arterial blood perfusion.     

肝脏灌注成像的CT扫描方法及应用价值

目的:探讨单层CT动态增强扫描测定肝硬化肝脏血流量的扫描方法及其应用价值。方法:15例经临床、实验室及B超检查诊断为肝硬化的患者,其中ChildB级患者10例,ChildC级患者5例。对照组为13例无肝脏疾病的患者。所有患者均选取同时含有肝脏、脾脏、主动脉和门静脉的层面进行单层CT动态增强扫描,绘制感兴趣区时间密度曲线,计算各血流灌注参数。结果:单层CT动态增强扫描测量肝组织的肝动脉灌注量(HAP)、门静脉灌注量(PVP)、总肝血流量(THBF)和肝动脉灌注指数(HPI)。正常组的HAP、PVP、THBF和HPI分别为(0.28±0.10)ml/min·ml、(1.18±0.40)ml/min·ml、(1.46±0.44)ml/min·ml和(19.73±5.81)%;肝硬化组的HAP、PVP、THBF和HPI分别为(0.23±0.11)ml/min·ml、(0.61±0.25)ml/min·ml、(0.84±0.32)ml/min·ml和(27.16±12.75)%。结论:肝脏单层CT灌注成像,可定量测定各项肝脏血流灌注参数,对肝硬化患者的量化诊断有一定的参考价值。     

Using slow-infusion MR arteriography and an implantable port system to assess drug distribution at hepatic arterial infusion chemotherapy

OBJECTIVE: The purpose of this study was to assess perfusion patterns seen on slow-infusion MR arteriography using the hepatic arterial infusion system compared with those seen on CT arteriography. SUBJECTS AND METHODS: In 37 patients with liver metastases who had implantable port systems for hepatic arterial infusion chemotherapy, slow-infusion MR arteriography using an infusion rate of 10 mL/hr through an implantable port and CT arteriography using an injection rate of 0.7 mL/sec were performed. In 15 of 37 patients, we evaluated enhancement patterns of tumors of the liver and visceral organs using slow-infusion MR arteriography. In all 37 patients, we compared slow-infusion MR arteriography with CT arteriography concerning intra- and extrahepatic perfusion patterns. RESULTS: On slow-infusion MR arteriography performed 10-20 min after initiation of infusion, tumors of the liver revealed significant enhancement with only a slight effect of systemic enhancement. In seven (19%) of 37 patients, intrahepatic distributions on slow-infusion MR arteriography differed from those on CT arteriography. In eight patients, the patterns of extrahepatic perfusion into the duodenum and the pancreas head differed on slow-infusion MR arteriography from those seen on CT arteriography. In addition, strong artifact caused by platinum coils in the gastroduodenal artery interfered with the evaluation of perfusion in the area around the coils on CT arteriography, whereas no imaging artifact was seen on slow-infusion MR arteriography. CONCLUSION: We believe that slow-infusion MR arteriography reflects the actual distribution of infused drugs more accurately than CT arteriography. When clinical complications occur during treatment, slow-infusion MR arteriography should be used to assess perfusion abnormalities.     

Pseudolesion in segments II and III of the liver on CT during arterial portography caused by aberrant right gastric venous drainage

We report three cases of pseudolesions caused by aberrant right gastric venous drainage (AGVD) in segment II/III of the liver as demonstrated on CT during arterial portography (CTAP). On CTAP, the lesions were seen as wedge-shaped perfusion defects, and on hepatic arteriography, AGVD directed to the area with the perfusion defect was visible in all three cases. When a perfusion defect is detected at the edge of segments II/III at CTAP, a pseudolesion caused by AGVD should be suspected.     

Alterations in hepatic perfusion resulting from splanchnic venous luminal compromise caused by pancreatic carcinoma

OBJECTIVE: We determined whether alterations in hepatic enhancement exist on dual phase helical CT of the liver in patients with splanchnic venous luminal compromise resulting from pancreatic adenocarcinoma. SUBJECTS AND METHODS: We examined the extent of hepatic enhancement on dual phase helical CT in 22 patients with pancreatic adenocarcinoma. Eleven patients had splanchnic venous luminal narrowing (flattening along at least 120 degrees of the circumference) of the superior mesenteric vein with (n = 3) or without (n = 8) portal vein involvement caused by tumor. In the remaining patients, splanchnic vasculature appeared normal. An additional 16 patients without pancreatic or hepatic abnormality who underwent dual phase helical CT served as control subjects. We compared the extent of arterial phase and portal venous phase enhancement among the three groups. RESULTS: The group of patients with splanchnic venous luminal compromise had significantly higher hepatic enhancement during the arterial phase (p < 0.01) and lower enhancement during the portal venous phase (p < 0.05) compared with the other two groups of patients. No significant difference in hepatic enhancement during either phase was noted between the control subjects and the patients with normal vasculature. CONCLUSION: Because hepatic enhancement correlates with perfusion, splanchnic venous luminal compromise resulting from pancreatic adenocarcinoma likely causes decreased portal venous flow and compensatory increased hepatic arterial flow. This finding supports other evidence of a homeostatic mechanism that maintains hepatic perfusion.     

Effects of prostaglandin E(1) injection through the superior mesenteric artery on the hemodynamics of hepatocellular carcinoma.

OBJECTIVE: The purpose of our study was to assess the effects of portal blood flow on contrast enhancement in hepatocellular carcinoma lesions on CT hepatic arteriography. SUBJECTS AND METHODS: We examined 43 tumors in 39 patients who simultaneously underwent CT during arterial portography and CT hepatic arteriography for examination of liver tumors and then CT hepatic arteriography with prostaglandin E(1) injection via the superior mesenteric artery. All lesions pathologically confirmed to be hepatocellular carcinomas exhibited portal perfusion defects on CT during arterial portography. Changes in CT attenuation, size, and shape of liver tumors visualized on CT hepatic arteriography after intraarterial injection of prostaglandin E(1) were studied. In addition, changes in CT attenuation of the liver parenchyma surrounding the tumor were measured. RESULTS: The CT attenuation increased significantly after injection of prostaglandin E(1) in 91% (39/43) of the lesions (mean increase from 176.4 to 206.6 H; p = 0.0006, paired t test). The size and shape of the enhanced area generally did not change. The CT attenuation of the liver parenchyma surrounding each liver tumor significantly decreased in 58% (25/43) of the hepatocellular carcinoma lesions (mean decrease from 94.8 to 92.0 H; p = 0.0166, paired t test) and lesion conspicuity increased in 91% (39/43) of the tumors. CONCLUSION: Lesion conspicuity on CT hepatic arteriography between hepatocellular carcinoma and the surrounding liver parenchyma increased because of greater portal perfusion after the prostaglandin E(1) injection.     

Hepatic entropy and uniformity: additional parameters that can potentially increase the effectiveness of contrast enhancement during abdominal CT

AIM: To determine how hepatic entropy and uniformity of computed tomography (CT) images of the liver change after the administration of contrast material and to assess whether these additional parameters are more sensitive to tumour-related changes in the liver than measurements of hepatic attenuation or perfusion. MATERIALS AND METHODS: Hepatic attenuation, entropy, uniformity, and perfusion were measured using multi-phase CT following resection of colorectal cancer. Based on conventional CT and fluorodeoxyglucose positron emission tomography, 12 patients were classified as having no evidence of malignancy, eight with extra-hepatic tumours only, and eight with metastatic liver disease. RESULTS: Hepatic attenuation and entropy increased after CM administration whereas uniformity decreased. Unlike hepatic attenuation, entropy and uniformity changed maximally in the arterial phase. No significant differences in hepatic perfusion or attenuation were found between patient groups, whereas arterial-phase entropy was lower (p=0.034) and arterial-phase uniformity was higher (p=0.034) in apparently disease-free areas of liver in patients with hepatic metastases compared with those with no metastases. CONCLUSION: Temporal changes in hepatic entropy and uniformity differ from those for hepatic attenuation. By reflecting the distribution of hepatic enhancement, these additional parameters are more sensitive to tumour-related changes in the liver than measurements of hepatic attenuation or perfusion.     

Techniques for computed tomography of the liver

We recommend that the CT technique of choice for routine screening of the liver, especially when there is potential for neoplasia, is dynamic CT using a single monophasic bolus of not less than 150 mL of a 60% iodinated contrast agent and a dynamic incremental package yielding at least 7 sections/minute. Routine use of noncontrast CT prior to dynamic CT is not indicated unless there is suspicion of a hypervascular tumor. We prefer to examine these particular patients with delayed CT 4 to 6 hours after receiving at least 60 g of iodine, as lesion to liver contrast is superior to noncontrast CT. Other indications for delayed CT include indeterminate lesions on dynamic CT or CTAP and perfusion defects on CTAP. In patients who are possible candidates for hepatic tumor resection, more invasive techniques such as CTAP are indicated as they yield the highest sensitivity to focal hepatic lesions, especially small lesions. A combination of CTAP and MR, however, demonstrates a superior lesion detection rate than either modality alone. CT-Lipiodol is a useful technique for detecting and palliating hepatocellular carcinomas, especially in patients with concomitant cirrhosis.     

Improved diagnosis of hepatic perfusion disorders: value of hepatic arterial phase imaging during helical CT.

The liver has a unique dual blood supply, which makes helical computed tomography (CT) a highly suitable technique for hepatic imaging. Helical CT allows single breath-hold scanning without motion artifacts. Because of rapid image acquisition, two-phase (hepatic arterial phase and portal venous phase) evaluation of the hepatic parenchyma is possible, improving tumor detection and tumor characterization in a single CT study. The arterial and portal venous supplies to the liver are not independent systems. There are several communications between the vessels, including transsinusoidal, transvasal, and transplexal routes. When vascular compromise occurs, there are often changes in the volume of blood flow in individual vessels and even in the direction of blood flow. These perfusion disorders can be detected with helical CT and are generally seen as an area of high attenuation on hepatic arterial phase images that returns to normal on portal venous phase images; this finding reflects increased arterial blood flow and arterioportal shunting in most cases. Familiarity with the helical CT appearances of these perfusion disorders will result in more accurate diagnosis. By recognizing these perfusion disorders, false-positive diagnosis (hypervascular tumors) or overestimation of the size of liver tumors (eg, hepatocellular carcinoma) can be avoided.     

肝局灶性病变CT与MRI动态增强对照研究

目的:探讨肝局灶性病变在CT和MRI动态增强中的影像差异及其原因,以提高对CT及MRI各自动态增强表现的认识。方法:搜集17例肝脏局灶性病变患者的临床资料,其中7例肝细胞肝癌,5例海绵状血管瘤,2例腺瘤,2例局灶结节性增生,1例转移瘤。全部病例均分别行CT及MRI的平扫和三期动态增强扫描;MRI采用SE序列加快速扰相梯度回波序列,将CT和MR动态增强图像进行对照观察,包括动态增强各期的强化范围、强化方式和强化幅度,强化幅度的比较用病灶密度(信号)与肝脏密度(信号)的比值进行比较。结果:肝癌、腺瘤和局灶结节性增生在CT与MRI上强化范围相似。1例肝癌动脉期强化幅度MRI大于CT,3例肝癌和2例局灶结节性增生门脉期及延迟期强化幅度MRI大于CT,2例腺瘤增强各期强化幅度MRI均大于CT,以动脉期差异最大。5例海绵状血管瘤强化范围动脉期及门脉期MRI大于CT,延迟期则相仿。1例转移瘤CT增强各期均未见明显强化,MRI门脉期及延迟期可见环状强化。结论:肝局灶性病变CT与MRI动态增强表现存在一定的差异,主要表现为部分病变增强各期强化幅度MRI大于CT,尤以动脉期差异最大;部分病变增强范围MRI大于CT。     

Hepatic Blood Volume Imaging with the Use of Flat-Detector CT Perfusion in the Angiography Suite: Comparison with Results of Conventional Multislice CT Perfusion

PurposeTo prospectively determine the feasibility of flat-detector (FD) computed tomography (CT) perfusion to measure hepatic blood volume (BV) in the angiography suite in patients with hepatocellular carcinoma (HCC).Materials and MethodsTwenty patients with HCC were investigated with conventional multislice and FD CT perfusion. CT perfusion was carried out on a multislice CT scanner, and FD CT perfusion was performed on a C-arm angiographic system, before transarterial chemoembolization procedures. BV values of conventional and FD CT perfusion were measured within tumors and liver parenchyma. The arterial perfusion portion of CT perfusion BV was extracted from CT perfusion BV by multiplying it by a hepatic perfusion index. Relative values (RVs) for CT perfusion arterial BV and FD CT perfusion BV (FD BV) were defined by dividing BV of tumor by BV of parenchyma. Relationships between BV and RV values of these two techniques were analyzed.ResultsIn all patients, both perfusion procedures were technically successful, and all 33 HCCs larger than 10 mm were identified with both imaging methods. There were strong correlations between the absolute values of FD BV and CT perfusion arterial BV (tumor, r = 0.903; parenchyma, r = 0.920; both P < .001). Bland–Altman analysis showed a mean difference of −0.15 ± 0.24 between RVs for CT perfusion arterial BV and FD BV.ConclusionsThe feasibility of FD CT perfusion to assess BV values of liver tumor and surrounding parenchyma in the angiographic suite was demonstrated.     

Perfusion imaging of the liver: current challenges and future goals

Improved therapeutic options for hepatocellular carcinoma and metastatic disease place greater demands on diagnostic and surveillance tests for liver disease. Existing diagnostic imaging techniques provide limited evaluation of tissue characteristics beyond morphology; perfusion imaging of the liver has potential to improve this shortcoming. The ability to resolve hepatic arterial and portal venous components of blood flow on a global and regional basis constitutes the primary goal of liver perfusion imaging. Earlier detection of primary and metastatic hepatic malignancies and cirrhosis may be possible on the basis of relative increases in hepatic arterial blood flow associated with these diseases. To date, liver flow scintigraphy and flow quantification at Doppler ultrasonography have focused on characterization of global abnormalities. Computed tomography (CT) and magnetic resonance (MR) imaging can provide regional and global parameters, a critical goal for tumor surveillance. Several challenges remain: reduced radiation doses associated with CT perfusion imaging, improved spatial and temporal resolution at MR imaging, accurate quantification of tissue contrast material at MR imaging, and validation of parameters obtained from fitting enhancement curves to biokinetic models, applicable to all perfusion methods. Continued progress in this new field of liver imaging may have profound implications for large patient groups at risk for liver disease.