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Cirrhotic Nodules: Association between MR Imaging Signal Intensity and Intranodular Blood Supply¹

¹ From the Department of Radiology, Kanazawa Graduate School of Medical Science, 13-1 Takaramachi, Kanazawa 920-8641, Japan (R.S., O.M., S.K., N.T., J.S., T.G.); Department of Diagnostic Radiology, Fukuiken Saiseikai Hospital, Fukui, Japan (R.S., S.M.); and Department of Radiology, Shinshu University School of Medicine, Matsumoto, Japan (K.U., M.K.). Received August 10, 2004; revision requested October 19; revision received November 23; accepted January 12, 2005. Supported in part by the Ministry of Education, Science, Sports and Culture; Grant-in-Aid for Scientific Research (C), 14570841, 2003; and a Grant-in-Aid for Cancer Research from the Ministry of Health, Labor and Welfare. Address correspondence to R.S. e-mail: rieko{at}rad.m.kanazawa-u.ac.jp).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
PURPOSE: To retrospectively determine whether there is a relationship between the intranodular blood supply evaluated at computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) and the magnetic resonance (MR) imaging signal intensity of nodules associated with cirrhosis.

MATERIALS AND METHODS: Neither institutional review board approval nor informed consent was required for retrospective reviews of medical records and images. One hundred fourteen hepatocellular nodules 10 mm or greater in largest diameter in 58 patients (39 men, 19 women; mean age, 61 years) with cirrhosis were evaluated at CTAP, CTHA, and MR imaging. The CTAP and CTHA nodule findings were divided into three main types: Type A nodules were isoattenuating at CTAP and hypoattenuating at CTHA; type B nodules, slightly hypoattenuating at CTAP and hypoattenuating at CTHA; and type C nodules, strongly hypoattenuating at CTAP and hyperattenuating at CTHA. The relationships between the CTAP and CTHA findings and the MR imaging signal intensity among these nodules were analyzed by using the ² test.

RESULTS: On T1-weighted MR images, 27 (63%) of 43 type A nodules were hyperintense, nine (39%) of 23 type B nodules were isointense, and 19 (48%) of 40 type C nodules were hypointense; differences were not significant. On T2-weighted MR images, 31 (72%) of 43 type A nodules were hypointense (P < .05), 12 (52%) of 23 type B nodules were isointense, and 34 (85%) of 40 type C nodules were hyperintense (P < .05).

CONCLUSION: There was a significant association between intranodular blood supply and nodule signal intensity on T2-weighted MR images. However, study findings did not show whether the blood itself (ie, blood volume or blood flow amount) directly influenced the signal intensity.

© RSNA, 2005

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
Hepatocellular carcinoma (HCC) is one of the most common malignancies in many parts of the world. The majority of HCCs develop in cirrhotic livers, and early detection and characterization of HCCs are very important in the treatment of patients with cirrhosis. In Japan, more than 90% of HCCs are associated with hepatitis B or hepatitis C viral infection, and 70% of patients with HCC have hepatitis C (1,2). An increasing number of patients with HCC who have findings positive for the hepatitis C virus antibody have also been identified throughout the world (3). It has become possible to detect small early HCCs by performing periodic imaging in patients with these high-risk diseases. However, various other kinds of hepatocellular nodules are also often detected during the diagnostic work-up for possible HCC, and differentiating these nodules from HCC is important in the treatment of patients with cirrhosis (4–7).

According to the classification system proposed by the International Working Party of the World Congress of Gastroenterology (8), hepatocellular nodules can be divided into two main categories: dysplastic nodules and HCCs. Dysplastic nodules can be divided into two subtypes: low-grade dysplastic nodules and high-grade dysplastic nodules. Two types of human hepatocarcinogeneses have been identified (4,9–11). One is the de novo carcinogenesis, and the other is the multistep development of a high-grade dysplastic nodule into a dysplastic nodule with malignant foci, then into well-differentiated HCC, and then into definite classic HCC.

We previously analyzed the association between the intranodular blood supply evaluated with computed tomography (CT) during intraarterial contrast material injection and the histologic grade of malignancy of hepatocellular nodules (5,12). We found that the intranodular portal venous blood supply evaluated at CT during arterial portography (CTAP) gradually decreased, whereas the intranodular arterial blood supply observed at CT during hepatic arteriography (CTHA) first decreased and then increased in accordance with an increase in the malignancy grade of the hepatocellular nodule. As a result, it has become possible to estimate with high confidence the histologic grade of malignancy of nodules by evaluating the intranodular blood supply at imaging-based diagnosis.

We have also found the signal intensity at magnetic resonance (MR) imaging to be useful for estimating the malignancy grade of hepatocellular nodules (6,13). According to our previous analysis results, borderline lesions (ie, high-grade dysplastic nodules) and some early HCCs (highly well-differentiated HCC) (4,10) occasionally are hypointense relative to the surrounding cirrhotic liver parenchyma on T2-weighted MR images and hyperintense on T1-weighted MR images. On the other hand, we found that almost all moderately differentiated HCCs demonstrated areas of hyperintensity and that well-differentiated HCCs and some early HCCs demonstrated areas of isointensity on T2-weighted MR images. Earls et al (14) analyzed the signal intensity of hepatocellular nodules by using explanted cirrhotic livers and reported similar results. The reasons why borderline lesions and early HCCs are hypointense on T2-weighted MR images and hyperintense on T1-weighted MR images are still unclear, but it has been speculated that the intranodular blood sinusoid or blood flow might affect the signal intensities of these lesions.

This study was undertaken to retrospectively assess whether there is a relationship between the intranodular blood supplies evaluated with CTAP and CTHA and the MR imaging signal intensity of nodules associated with cirrhosis.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
The institutional review board of Kanazawa Graduate School of Medical Science requires neither its approval nor informed patient consent for retrospective reviews of medical records and images.

Study Patients
One hundred fourteen hepatocellular nodules 10 mm or greater in largest diameter (mean diameter, 16.2 mm; range, 10–30 mm) in 58 consecutive patients with cirrhosis between December 2000 and January 2002 who were examined with CTAP, CTHA, and MR imaging were included in the study. The patients were 39 men and 19 women, and they ranged in age from 43 to 72 years (mean age, 61 years). Hepatitis B virus–related liver cirrhosis was identified in 10 patients; hepatitis C virus–related cirrhosis, in 39 patients; both hepatitis B– and hepatitis C–related cirrhosis, in two patients; alcohol-related cirrhosis, in five patients; and primary biliary cirrhosis, in two patients. CTAP and CTHA examinations were performed within a mean of 8 days (range, 1–28 days) before or after MR imaging.

The diagnoses of 28 hepatocellular nodules were pathologically confirmed at surgical resection or percutaneous biopsy. The diagnoses of the remaining hepatocellular nodules were made when ultrasonography, CT, MR imaging, CTAP, and/or CTHA depicted a round nodule 10 mm or greater in largest diameter that was distinct from a cyst or cavernous hemangioma. To prevent the partial volume phenomenon from having any influence on the signal intensity, we excluded all nodules smaller than 10 mm in diameter from the study. Nodules with fat depositions and nodules surrounded by fatty liver tissue, as verified at chemical shift MR imaging—including T1-weighted fast multiplanar spoiled gradient-recalled-echo in-phase and out-of-phase sequences—also were excluded from analysis to avoid bias in the evaluation of the signal intensities of the nodules relative to the surrounding liver parenchyma.

CTAP and CTHA Examinations
CTAP and CTHA were performed after hepatic angiography by using a combined digital subtraction angiography (DFP 2000 A; Toshiba, Tokyo, Japan) and helical CT (Xvision SP; Toshiba) system called IVR-CT/Angio. After femoral artery puncture, a 4-F catheter was selectively placed in the superior mesenteric artery for CTAP and in the common or proper hepatic artery for CTHA. For CTAP, 5-mm collimation and a 7 mm/sec table speed were used. The duration of scanning was approximately 20 seconds during a single breath hold for a total scanned length of 14–18 cm. Overlapping reconstructions were obtained every 2.5 mm. Helical CT scanning began 25 seconds after the beginning of an infusion of 60 mL of iohexol (320 mg of iodine per milliliter) (Omnipaque; Daiichi, Tokyo, Japan) at 2 mL/sec, and 5 µg of prostaglandin E₁ (Palux; Taisyo, Tokyo, Japan) was injected into the superior mesenteric artery immediately before the contrast medium injection.

Approximately 10 minutes after CTAP was performed, CTHA scans were obtained with 5-mm collimation, a 6 mm/sec table speed, and 2.5-mm reconstruction intervals. CTHA scanning began 10 seconds after the start of the injection of iohexol (320 mg of iodine per milliliter) at 2 mL/sec. The infusion was continued throughout the scanning. In all patients, conventional CT (including nonenhanced CT) was performed separately, on a different day, before the CTAP and CTHA procedures. The angiographic procedures were performed by radiologists who each had more than 6 years of experience performing abdominal angiography (R.S., O.M., S.K., N.T., J.S., K.U.).

MR Imaging
MR imaging was performed with a 1.5-T unit (Signa Horizon; GE Medical Systems, Milwaukee, Wis). All images were obtained in the transverse plane by using a phased-array multicoil. The matrix size was 128 x 256 or 256 x 256. The following unenhanced MR imaging examinations were performed: Respiratory-triggered fast spin-echo T2-weighted imaging (4000/90 [repetition time msec/echo time msec], two acquisitions) was performed with frequency-selective fat saturation, a section thickness of 8 mm, and a 2-mm intersection gap. Respiratory compensation spin-echo T1-weighted imaging (500/9, two acquisitions) was performed by using a section thickness of 8 mm and a 2-mm intersection gap. Breath-hold T1-weighted fast multiplanar spoiled gradient-recalled-echo in-phase (150–200/4.4, one acquisition) and out-of-phase (120–180/2.2, one acquisition) imaging examinations were performed with a flip angle of 90°, an 8-mm section thickness, and a 2-mm intersection gap. The hepatocellular nodule signal intensities evaluated at the respiratory-triggered fast spin-echo T2-weighted and respiratory compensation spin-echo T1-weighted examinations were used in our analyses.

Image Evaluation
The CTAP findings of hepatocellular nodules, relative to the findings of the surrounding cirrhotic liver tissue, were classified into three groups: The nodules in group A were isoattenuating—that is, not visualized—indicating that the intranodular portal venous blood supply was almost the same as the blood supply of the surrounding regenerative nodules. The nodules in group B were slightly hypoattenuating relative to the surrounding liver parenchyma—that is, they had an attenuation higher than that of the intrahepatic inferior vena cava, into which almost no contrast medium flowed during scanning—indicating decreased but not absent intranodular portal venous blood flow. The nodules in group C were strongly hypoattenuating—that is, the entire nodule was more hypoattenuating than the inferior vena cava—indicating an absent intranodular portal venous supply.

The CTHA nodular findings, relative to the surrounding cirrhotic liver tissue findings, also were categorized into three groups: The nodules in group A were isoattenuating—that is, not visualized—indicating that the intranodular arterial blood supply was almost the same as the blood supply of the surrounding liver parenchyma. The nodules in group B were hypoattenuating, indicating a decreased intranodular arterial supply. The nodules in group C were hyperattenuating, indicating an increased intranodular arterial supply.

The combined CTAP and CTHA nodular findings were divided into three groups: Group A nodules were isoattenuating at CTAP and hypoattenuating at CTHA (Fig 1a, 1b). Group B nodules were slightly hypoattenuating at CTAP and hypoattenuating at CTHA (Fig 2a, 2b). Group C nodules were strongly hypoattenuating at CTAP and hyperattenuating at CTHA (Fig 3a, 3b). Eight nodules with other CTAP-CTHA finding combinations were excluded from our analyses because there were too few of them for statistical analysis.

View larger version (188K): [in this window] [in a new window] [Download PPT slide]   Figure 1a. High-grade dysplastic nodule (arrow) diagnosed at biopsy of liver with hepatitis C–related cirrhosis. Arrowhead points to associated HCC. (a) Transverse CTAP scan shows isoattenuating (CTAP group A) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group B). This lesion was classified as a CTAP-CTHA type A nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hypointense.

View larger version (175K): [in this window] [in a new window] [Download PPT slide]   Figure 1b. High-grade dysplastic nodule (arrow) diagnosed at biopsy of liver with hepatitis C–related cirrhosis. Arrowhead points to associated HCC. (a) Transverse CTAP scan shows isoattenuating (CTAP group A) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group B). This lesion was classified as a CTAP-CTHA type A nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hypointense.

View larger version (190K): [in this window] [in a new window] [Download PPT slide]   Figure 1c. High-grade dysplastic nodule (arrow) diagnosed at biopsy of liver with hepatitis C–related cirrhosis. Arrowhead points to associated HCC. (a) Transverse CTAP scan shows isoattenuating (CTAP group A) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group B). This lesion was classified as a CTAP-CTHA type A nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hypointense.

View larger version (190K): [in this window] [in a new window] [Download PPT slide]   Figure 1d. High-grade dysplastic nodule (arrow) diagnosed at biopsy of liver with hepatitis C–related cirrhosis. Arrowhead points to associated HCC. (a) Transverse CTAP scan shows isoattenuating (CTAP group A) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group B). This lesion was classified as a CTAP-CTHA type A nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hypointense.

View larger version (165K): [in this window] [in a new window] [Download PPT slide]   Figure 2a. Well-differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows slightly hypoattenuating (CTAP group B) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type B nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is isointense.

View larger version (182K): [in this window] [in a new window] [Download PPT slide]   Figure 2b. Well-differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows slightly hypoattenuating (CTAP group B) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type B nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is isointense.

View larger version (144K): [in this window] [in a new window] [Download PPT slide]   Figure 2c. Well-differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows slightly hypoattenuating (CTAP group B) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type B nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is isointense.

View larger version (162K): [in this window] [in a new window] [Download PPT slide]   Figure 2d. Well-differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows slightly hypoattenuating (CTAP group B) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hypoattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type B nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hyperintense. (d) On transverse T2-weighted MR image (4000/90), the nodule is isointense.

View larger version (141K): [in this window] [in a new window] [Download PPT slide]   Figure 3a. Moderately differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows strongly hypoattenuating (CTAP group C) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hyperattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type C nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hypointense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hyperintense.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 3b. Moderately differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows strongly hypoattenuating (CTAP group C) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hyperattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type C nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hypointense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hyperintense.

View larger version (134K): [in this window] [in a new window] [Download PPT slide]   Figure 3c. Moderately differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows strongly hypoattenuating (CTAP group C) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hyperattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type C nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hypointense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hyperintense.

View larger version (156K): [in this window] [in a new window] [Download PPT slide]   Figure 3d. Moderately differentiated HCC (arrow) diagnosed by means of surgical resection from liver with hepatitis C–related cirrhosis. (a) Transverse CTAP scan shows strongly hypoattenuating (CTAP group C) nodule in liver segment VIII. (b) On transverse CTHA scan, the nodule in a is hyperattenuating (CTHA group C). This lesion was classified as a CTAP-CTHA type C nodule. (c) On transverse T1-weighted MR image (500/9), the same nodule is hypointense. (d) On transverse T2-weighted MR image (4000/90), the nodule is hyperintense.

All CT and MR images were retrospectively interpreted in consensus by three radiologists (R.S., O.M., K.U., one with more than 7 years and the two others with more than 15 years of experience performing liver imaging). The radiologists evaluated the CT or MR imaging findings without knowing the findings of the other examination, and they evaluated the two sets of images subjectively and independently. Disagreements were resolved by consensus, and interobserver correlation was not analyzed because of the simplicity of the interpretations. The correlation between MR imaging signal intensity and intranodular blood supply relative to the surrounding liver parenchyma blood supply evaluated at CTAP and CTHA was analyzed for all nodules included in the study. When a given nodule had heterogeneous intranodular attenuation or signal intensity, the findings in the greater part of the nodule were used for analysis.

Statistical Analyses
Statistical analyses were performed by using the ² test to evaluate associations between the intranodular blood supply groups and the MR imaging signal intensities. Moreover, statistical analyses of each combination of CTAP and CTHA findings were performed. Differences were considered to be significant when the P value was less than .05. All statistical analyses were performed by using a statistical software package (StatView, version 5.0; SAS Institute, Cary, NC).

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
Forty-three nodules were categorized into CTAP group A; 30 nodules, into CTAP group B; and 41 nodules, into CTAP group C. Five nodules were categorized into CTHA group A; 66 nodules, into CTHA group B, and 43 nodules, into CTHA group C. Forty-three nodules were categorized into combined CTAP-CTHA group A; 23 nodules, into CTAP-CTHA group B; and 40 nodules, into CTAP-CTHA group C (Table 1).

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

The histologic background of signal intensity on MR images of HCCs has been analyzed. The areas of hyperintensity in HCCs seen on T1-weighted MR images were considered to be due to fat deposition in one-third of the cases (16,17). The contribution of copper accumulation to this hyperintensity has been a subject of controversy (18,19). However, Ebara et al (20), by directly measuring the concentration of copper in HCC tumors and in the surrounding liver tissues, reconfirmed the significant relationship between copper accumulation and hyperintensity on T1-weighted MR images. On the other hand, the areas of hyperintensity in HCCs seen on T2-weighted MR images have been considered to be due to increased numbers of blood sinusoids with increased amounts of blood, although there is no definite scientific confirmation of this theory (17,18,21).

In our previous study, almost all borderline lesions and the majority of the well-differentiated HCCs had areas of hyperintensity on T1-weighted MR images, which were probably due to fatty metamorphosis in one-third of the cases (6). In the remaining two-thirds of the cases, the histologic background was uncertain. Our analysis revealed no definite relationship between hyperintensity at T1-weighted MR imaging and copper accumulation in borderline lesions (22). On T2-weighted MR images, the majority of the borderline lesions had areas of hypointensity (6,14) and the histologic background was not clarified.

We previously reported that siderotic dysplastic nodules showed areas of hypointensity on T2-weighted MR images (23). However, the frequency of siderotic dysplastic nodules with more iron deposition than the surrounding regenerative nodules was only about 25% (23). Because approximately one-third of small moderately differentiated HCCs also have areas of hyperintensity on T1-weighted MR images (17), it is impossible to estimate the grade of malignancy according to the findings on these images. However, the combination of signal intensity on T1-weighted images and signal intensity on T2-weighted images is useful in the differential diagnosis of hepatocellular nodules in cirrhotic livers. A nodule that is hyperintense on T1-weighted images and hypointense on T2-weighted images usually indicates that the lesion is borderline or an early well-differentiated HCC. In contrast, a nodule that is hyperintense on T1-weighted images and isointense on T2-weighted images usually represents a well-differentiated HCC (6,17).

In this study, we analyzed the relationship between the intranodular blood supply evaluated with CTAP and CTHA and the signal intensity at MR imaging because there has been speculation that the blood volume or blood flow amount in the nodule may influence the differences in signal intensity among various kinds of hepatocellular nodules associated with liver cirrhosis. There was a significant association between the intranodular portal venous and arterial blood supplies and the signal intensity on T2-weighted MR images—namely, the signal intensity on T2-weighted images increased as the intranodular portal venous supply decreased. On the other hand, the nodules with decreased intranodular arterial supplies demonstrated areas of hypointensity on T2-weighted MR images, and increased signal intensity was observed with increased intranodular arterial supply. However, it was not clear whether the blood itself (ie, blood volume or blood flow amount) directly influenced the signal intensity.

In addition to showing hypovascularity at both CTHA (to assess arterial supply) and CTAP (to assess portal venous supply), dysplastic nodules (ie, adenomatous hyperplasia) show hypercellularity with narrowed internal sinusoids relative to the surrounding liver parenchyma histologically (4,8). Therefore, it could be speculated that dysplastic nodules demonstrate areas of hypointensity on T2-weighted images probably because of a decreased intranodular blood volume. In contrast, the increased number of abnormal arteries (or tumor sinusoids) revealed at CTHA and histologic analysis may cause hyperintensity on T2-weighted MR images because of the increased blood volume or increased number of blood spaces with retarded blood flow. However, as expected on the basis of the findings of dynamic portal venous phase CT, at which classic HCCs usually show hypoattenuation relative to the surrounding liver tissue, the total volume of blood spaces in HCC may not be greater than that in the surrounding regenerative nodules. Therefore, despite the observation of significant associations between increased arterial supply and hyperintensity on T2-weighted MR images and between decreased portal venous supply and hyperintensity on T2-weighted MR images, the proposal that increased arterial nodular blood supply has a direct effect on T2-weighted imaging signal intensity is questionable. Further investigation is needed.

In this analysis, it became clear that there is a strong relationship between the intranodular blood supply evaluated with CTAP and CTHA and the signal intensity at MR imaging. As we previously reported, the progression of hepatocellular nodules associated with liver cirrhosis to hypervascular HCC can be well predicted by evaluating the intranodular blood supply at CTAP and CTHA (24). Therefore, knowledge of the MR imaging signal intensity is also clinically valuable for managing the treatment of patients with cirrhosis.

There were limitations in this study. First, histologic specimens of only a small number of the nodules were obtained; therefore, histologic analysis was not performed. Second, the same reviewers interpreted the findings of CTAP, CTHA, and MR imaging. In addition, a few nodules that had intranodular blood supply patterns that were different from those seen in CTAP-CTHA groups A, B, and C were excluded from the study, and gadolinium-enhanced MR images were not evaluated in this study.

In conclusion, there was a significant association between the intranodular portal venous and arterial blood supplies and the T2-weighted MR imaging signal intensity in various types of hepatocellular nodules associated with liver cirrhosis. Namely, the signal intensity on T2-weighted MR images increased as the intranodular portal venous blood supply decreased. On the other hand, the nodules that had decreased intranodular arterial supplies demonstrated areas of hypointensity on T2-weighted MR images, and increases in signal intensity were observed with increases in intranodular arterial supply. However, it was not clear whether the blood itself (blood volume or blood flow amount) directly influenced the signal intensity.

	FOOTNOTES

 

Abbreviations: CTAP = CT during arterial portography • CTHA = CT during hepatic arteriography • HCC = hepatocellular carcinoma

Authors stated no financial relationship to disclose.

Author contributions: Guarantors of integrity of entire study, R.S., O.M.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, all authors; clinical studies, R.S., O.M., S.K., N.T., J.S., T.G., M.K., S.M.; statistical analysis, R.S., S.K., K.U., T.G., S.M.; and manuscript editing, R.S., O.M., N.T., J.S., K.U., T.G., M.K., S.M.

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TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 

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