Gastrointest Radiol 17:49-52 (1992)
Gastrointestinal
Radiology 9 Springer-Verlag New York Inc. 1992
MR Imaging of Hepatocellular Carcinoma at 1.5 Tesla Richard E. Rosenthal and Peter L. Davis Department of Radiology, University of Pittsburgh, Pittsburgh NMR Institute, Pittsburgh, Pennsylvania, USA
Abstract. The authors investigated the magnetic resonance appearance of hepatocellular carcinoma using a 1.5-Tesla magnet. Twenty-four patients with pathologically p r o v e n hepatocellular carcinoma had magnetic resonance imaging (MRI) studies, which were retrospectively reviewed. All patients were imaged with at least two of the following techniques: (1) Tl-weighted (T1W), (2) Tl-weighted with GdD T P A e n h a n c e m e n t (T1W-E), (3) T2-weighted (T2W), (4) proton density (PD), and (5) gradientrecalled echoes (GRE). T1W images were equal to T2W images for tumor detection using a grading system. T I W images were slightly better than T2W images for the total number of lesions detected. The other pulsing techniques (PD, T1W-E, and GRE) detected fewer lesions. Eight cases of hepatocellular carcinoma (33%) had n o n h o m o g e n e o u s increased signal intensity on both T I W and T2W images. The authors conclude that T1W images are equal to T2W images for detection of hepatocellular carcinoma. The authors also conclude that 33% of hepatocellular carcinomas have an imaging pattern with increased signal intensity on both T1W and T2W images. This pattern is atypical for most other hepatic masses and hence can be used to suggest the mass is hepatocellular carcinoma.
Key words: Liver, MR s t u d i e s - - L i v e r neoplasms, MR s t u d i e s - - M a g n e t i c studies.
resonance,
comparative
Magnetic resonance imaging (MRI) with its superior soft tissue contrast and greater safety due to the lack
Address offprint requests to: Richard E. Rosenthal, D.O., De-
partment of Radiology, Cooper Hospital/University Medical Center, One Cooper Plaza, Camden, NJ 08103, USA
of ionizing radiation is an attractive alternative to contrast-enhanced c o m p u t e d tomography (CT) for detecting and diagnosing liver tumors. Various reports [1-5] have shown MRI to be equal or superior to contrast-enhanced CT in detecting and characterizing liver tumors. Hepatocellular carcinoma is the most c o m m o n primary liver tumor. It is most common in Africa and Asia due to the high prevalence of hepatic infections. Hepatocellular carcinoma is associated with hepatitis, cirrhosis, and chemical injuries in the United States. We evaluated 24 cases of hepatocellular carcinoma imaged by MR to determine how well MR detects this type of tumor.
Materials and Methods Between July 17, 1987 and February 27, 1990, 24 patients with pathologically proven hepatocellular carcinoma had MRI studies. One additional patient had pathologically proven hepatocellular carcinoma, but was not used in the research because all of the images were obtained following the administration of Gd-DTPA. Two patients in the study had an additional lesion in the liver (hemangioma and cholangiocarcinoma). Two patients had recurrence of a previously resected hepatocellular carcinoma. One patient had two studies but only the most recent was used. There were 18 male patients and six female patients with an average age of 51 years (range 18-71 years). All studies were performed with a 1.5-Tesla superconducting magnet (Signa; GE Medical Systems, Milwaukee, WI, USA) with standard hardware and software. Patients were imaged with at least two of the followingpulsing techniques: (1) Tl-weighted (T1W), (2) Tl-weighted with Gd-DTPA enhancement (TI W-E), (3) T2-weighted (T2W), (4) proton density (PD), and (5) gradient-recalled echoes (GRE). All of the patients had T1W images (TR 300-650 ms, TE 20 ms), 23 patients had PD images (TR 2022-3200 ms, TE 20-30 ms), 22 patients had T2W images (TR 2022-3200 ms, TE 80 ms), 20 patients had GRE images (20-45~ TR 25-50 ms, TE 13 ms), and nine patients had T1W-E images (TR 300-650 ms, TE 20 ms). All studies were performed using a body coil in the axial and coronal planes. Tenmillimeter slice thickness was used with a gap of 2 mm and a matrix of 128 x 128. The field of view varied from 32-40 cm. The number of excitations varied from 2-4. Gd-DTPA was administered intravenously to nine patients at a dose of 0.1 mmol/kg of
50
R.E. Rosenthal and P.L. Davis: Hepatocellular C a r c i n o m a
Table 1. Age, sex, n u m b e r of t u m o r s , size of largest tumor, and n u m b e r of tumors detected for each pulsing s e q u e n c e Patient no
Age (yr)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Sex
53 53 41 51 45 68 57 63 35 58 46 61 48 18 44 56 50 23 71 65 51 42 65 56
No. of tumors
M M F M M M M M M M M M M F M M F F M F M F M M
2 4 4 6 5 1 1 1 1 2 2 1 1 8 1 1 1 1 4 1 3 2 2 7
Size of largest tumor (cm) 7 4 3 8 14 2 10 3 9 2 8 14 1 20 14 3 4 14 7 14 4 5 8 5
N u m b e r of tumors detected TIW
T2W
PD
GRE
TIW-E
2 2 4 6 5 1 1 1 1 2 2 1 1 6 1 1 0 1 4 1 3 1 2 7
2 2 4 3 3 0 1 0 1 0 2
2 1 4 3 2 0 0 1 1 0 2
2 4 1 2 2 0 0 0 1 0
0 1
0 8 1
1 5 1 1 1 1 4 1 1 2 2 7
1 1 4 1 1 2 2 7
0
0 0 0 0
1
1 0 3 0
1 2 1
0 2 2
1
T1W, Tl-weighted; T2W, T2-weighted; PD, Proton density; GRE, Gradient-recalled echoes; T1W-E, T l - w e i g h t e d e n h a n c e d .
Table 2. Conspicuity of hepatocellular carcinomas by grading system Patient
T 1W
T2W
PD
GRE
4 2 3 4 5 4 4 5 2 3 3 2 4 3 3 1 1 2 3 4 3 2 2 2
3 3 3 3 4 1 3 1 4 1 1
2 1 2 2 3 1 1 4 2 1 1
1 4 1 1 2 1 1 1 1
3 4 5
1 2 2 1 3 4 4 1 1 4 2 3
T 1W-E
no.
1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 16 17 18 19 20 21 22 23 24
4 5 4 3 1 5 4 4
See Table 1 abbreviations.
1 5
body weight. I m a g e s were obtained immediately after the intraven o u s administration of G d - D T P A . T w o radiologists, who had prior knowledge of the pathological diagnosis, retrospectively reviewed all of the images, evaluating n u m b e r , size, and signal characteristics of the lesions. T h e images for each patient were ranked relative to each other for detectability of the lesion, from most difficult to easiest; the ranking was also based on the n u m b e r of pulsing techniques used. F o r example, if five pulsing techniques were used, then the images were ranked from 1 (for the most difficult) to 5 (for the easiest), but if two pulsing techniques were used, then the scoring range on the studies for that patient only went from 1 to 2. T h o s e studies using three and four pulsing techniques followed this ranking s y s t e m accordingly.
1
Results 1 1 1 1
4
1 1 1 1
2 2 4
1 1 1
3
Tables 1 and 2 are a summary of the data collected. Tumors ranged from !-20 cm in size and one to eight in number. According to our scoring system, T1W image were equal to T2W images for tumor detection. When the total number of lesions detected was counted, however, TIW images proved to be slightly better than T2W images. Images using the other pulsing techniques (PD, T1W-E, and GRE) detected fewer lesions. Figure 1 shows the usual signal characteristics of a hepatocellular carcinoma being diminished in signal intensity on T1W images and increased in signal intensity on T2W images. Figure 2
R.E. Rosenthal and P.L. Davis: Hepatocellular Carcinoma
Fig. 1. Hepatocellular carcinoma occupies entire left lobe of liver, most of anterior segment of right lobe of liver, and satellite lesions in posterior segment of right lobe of liver. A SE 700/20 axial image demonstrates diminished signal intensity and B SE 2800/80 axial image shows increased signal intensity. Fig. 2. Hepatocellular carcinoma with two lobulated masses in the right lobe of the liver with nonhomogenous increased signal intensity on both A SE 400/20 axial image and B SE 2500/80 axial image.
d e m o n s t r a t e s an atypical a p p e a r a n c e of eight hepatocellular c a r c i n o m a s (33%) that had nonhomogeneous increased signal intensity on both T1W and T2W pulsing techniques.
Discussion Hepatocellular c a r c i n o m a can be treated by surgical removal. M R I plays a crucial role in detecting and determining the full extent of this disease prior to surgery. Therefore, the o p t i m u m pulsing sequences should be used. In our research, detection of hepatocellular c a r c i n o m a was essentially equal on both T1W and T2W pulsing sequences. Other pulsing se-
51
quences (PD, G R E , and T I W - E ) were less effective. N e w experimental liver-contrast agents show promise in increasing the l i v e r - l e s i o n tissue contrast and this should increase detectability of tumors [6-11]. Various pathological findings that are specific for hepatocellular c a r c i n o m a have been found in MRI. This includes the p r e s e n c e of a pseudocapsule [3, 12-14], mosaic pattern [3, 13, 15], nodule within a nodule [16], and t u m o r t h r o m b u s in the portal vein [17]. In our series, one third (33%) of the hepatocellular carcinomas were hyperintense on both T1W and T2W images. We believe this pattern is atypical for m o s t other hepatic m a s s e s and hence can be used to suggest the mass is hepatocellular carcinoma. The increased signal intensity on T1W images has been reported in other articles [3, 14], but the rate of occurrence of increased signal intensity on both T1W and T2W pulse sequences has not been previously published. The increased signal intensity on both the T I W and T 2 W images is due to fatty metamorphosis in hepatocellular c a r c i n o m a [18]. Peters [19] has shown fat to be present in t u m o r cells that are well differentiated, because the fat is p r o d u c e d and not excreted. The m o s t c o m m o n entity that mimics hepatocellular c a r c i n o m a is a complicated cyst. This entity has hyperintensity on both T1W and T2W images
52
due to its high protein and hemorrhage content, but can be differentiated from hepatocellular carcinoma by its increased signal intensity consistent with fluid on T2W images. Other rare fatty tumors which should be included in the differential diagnosis include lipoma [20, 21], angiomyolipoma [21-24], adenoma [25], and myelolipoma [26]. To conclude, MRI with T1W and T2W pulse sequences are equal in detectability of hepatocellular carcinoma. Tumors in the liver with increased signal intensity on both TIW and T2W pulse sequences are highly suspicious for hepatocellular carcinoma. References 1. Barakos JA, Goldberg HI, Brown J J, Gilbert TJ. Comparison of computed tomography and magnetic resonance imaging in the evaluation of focal hepatic lesions. Gastrointest Radiol 1990;15:93-101 2. Doyle FH, Pennock JM, Banks LM, et al. Nuclear magnetic resonance imaging of the liver: initial experience. A JR 1982;138:193-200 3. ltoh K, Nishimura K, Togashi K, et al. Hepatocellular carcinoma: MR imaging. Radiology 1987;164:21-25 4. Moss AA, Goldberg HI, Stark DB, et al. Hepatic tumors: magnetic resonance and CT appearance. Radiology 1984;150:141-147 5. Vermess M, Leung AW-L, Bydder GM, Steiner RE, Blumgart LH, Young IR. MR imaging of the liver in primary hepatocellular carcinoma. J Comput Assist Tomogr 1985:9:749-754 6. Fretz C J, Elizondo G, Weissleder R, Hahn PF, Stark DD, Ferrucci JT. Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer. Radiology 1989;172:393-397 7. Marchal G, Van Hecke P, Demaerel P, et al. Detection of liver metastasis with superparamagnetic iron oxide in 15 patients: results of MR imaging at 1.5T. A JR 1989;152:771-775 8. Saini S, Stark DD, Hahn PF, et al. Ferrite particles: a superparamagnetic MR contrast agent for enhanced detection of liver carcinoma. Radiology 1987;162:217-222 9. Stark DD, Weissleder R, Elizondo G, et al. Superparamagnetic iron oxide: clinical application as a contrast agent for MR imaging of the liver. Radiology 1988;168:297-301 10. Thickman D, Hendrick RE, Jerjian KA, Schanker CS. Liver-
R.E. Rosenthal and P.L. Davis: Hepatocellular Carcinoma lesion tissue contrast on MR images: effect of iron oxide concentration and magnetic field strength. Radiology 1990;176:557-562 11. Tsang Y-M, Stark DD, Chen Mc-M, Weissleder R, Wittenberg J, Ferrucci JT. Hepatic micrometastases in the rat: ferrite-enhanced MR imaging. Radiology 1988;167:21-24 12. Ebara M, Obto M, Wantanabe Y, et al. Diagnosis of small hepatocellular carcinoma: correlation of MR imaging and tumor histologic studies. Radiology 1986; 159:371-377 13. Itai Y, Ohtomo K, Furui S, Minami M, Yoshikawa K, Yashiro N. MR imaging of hepatocellular carcinoma. J Cornput Assist Tomogr 1986;10:963-968 14. Rummeny E, Weissleder R, Stark DD, et al. Primary liver tumors: diagnosis by MR imaging. A JR 1989;152:63-72 15. Choi BI, Lee GK, Kim ST, Hart MC. Mosaic pattern of encapsulated hepatocellular carcinoma: correlation of magnetic resonance imaging and pathology. Gastrointest Radiol 1990;15:238-240 16. Mitchell DG, Rubin R, Siegelman ES, Burk DL, Rifkin MD. Hepatocellular carcinoma within siderotic regenerative nodules: appearance as a nodule within a nodule on MR images. Radiology 1991 ;178:101-103 17. Ohtomo K, Itai Y, Furui S, Yoshikawa K, Y.ashiro N, lio M. MR imaging of portal vein thrombus in hepatocellular carcinoma. J Comput Assist Tomogr 1985;9:328-329 18. Yoshikawa J, Matsui O, Takashima T, et al. Fatty metamorphosis in hepatocellular carcinoma: radiologic features in l0 cases. A JR 1988;151:717-720 19. Peters RL. Pathology of hepatocellular carcinoma. In: Okuda K, Peters RL, eds. Hepatocellular carcinoma. New York: Wiley, 1976:107-168 20. Ramchand S, Ahmed Y, Baskerville L. Lipoma of the liver. Arch Pathol 1970;90:331-333 21. Roberts JL, Fishman EK, Hartman DS, Sanders R, Goodman Z, Siegelman SS. Lipomatous tumors of the liver: evaluation with CT and US. Radiology 1986;158:613-617 22. Goodman ZD, Ishak KG. Angiomyolipomas of the liver. Am J Surg Pathol 1984;8:745-750 23. Pounder DJ. Hepatic angiomyolipoma. Am J Surg Pathol 1982;6:677-681 24. Kawarada Y, Mizumoto R. Angiomyolipoma of the liver. Am J Gastroenterol 1983;78:434-439 25. Angres G, Carter JB, Velasco JM. Unusual ring in liver cell adenoma. A JR 1980;135:172-174 26. Rubin E, Russinovich NAE, Luna RF, Tishler JMA, Wilkerson JA. Myelolipoma of the liver. Cancer 1984;54:2043-2046
Received: June 17, 1991; accepted: July 24, 1991
Gastrointestinal
Radiology 9 Springer-Verlag New York Inc. 1992
MR Imaging of Hepatocellular Carcinoma at 1.5 Tesla Richard E. Rosenthal and Peter L. Davis Department of Radiology, University of Pittsburgh, Pittsburgh NMR Institute, Pittsburgh, Pennsylvania, USA
Abstract. The authors investigated the magnetic resonance appearance of hepatocellular carcinoma using a 1.5-Tesla magnet. Twenty-four patients with pathologically p r o v e n hepatocellular carcinoma had magnetic resonance imaging (MRI) studies, which were retrospectively reviewed. All patients were imaged with at least two of the following techniques: (1) Tl-weighted (T1W), (2) Tl-weighted with GdD T P A e n h a n c e m e n t (T1W-E), (3) T2-weighted (T2W), (4) proton density (PD), and (5) gradientrecalled echoes (GRE). T1W images were equal to T2W images for tumor detection using a grading system. T I W images were slightly better than T2W images for the total number of lesions detected. The other pulsing techniques (PD, T1W-E, and GRE) detected fewer lesions. Eight cases of hepatocellular carcinoma (33%) had n o n h o m o g e n e o u s increased signal intensity on both T I W and T2W images. The authors conclude that T1W images are equal to T2W images for detection of hepatocellular carcinoma. The authors also conclude that 33% of hepatocellular carcinomas have an imaging pattern with increased signal intensity on both T1W and T2W images. This pattern is atypical for most other hepatic masses and hence can be used to suggest the mass is hepatocellular carcinoma.
Key words: Liver, MR s t u d i e s - - L i v e r neoplasms, MR s t u d i e s - - M a g n e t i c studies.
resonance,
comparative
Magnetic resonance imaging (MRI) with its superior soft tissue contrast and greater safety due to the lack
Address offprint requests to: Richard E. Rosenthal, D.O., De-
partment of Radiology, Cooper Hospital/University Medical Center, One Cooper Plaza, Camden, NJ 08103, USA
of ionizing radiation is an attractive alternative to contrast-enhanced c o m p u t e d tomography (CT) for detecting and diagnosing liver tumors. Various reports [1-5] have shown MRI to be equal or superior to contrast-enhanced CT in detecting and characterizing liver tumors. Hepatocellular carcinoma is the most c o m m o n primary liver tumor. It is most common in Africa and Asia due to the high prevalence of hepatic infections. Hepatocellular carcinoma is associated with hepatitis, cirrhosis, and chemical injuries in the United States. We evaluated 24 cases of hepatocellular carcinoma imaged by MR to determine how well MR detects this type of tumor.
Materials and Methods Between July 17, 1987 and February 27, 1990, 24 patients with pathologically proven hepatocellular carcinoma had MRI studies. One additional patient had pathologically proven hepatocellular carcinoma, but was not used in the research because all of the images were obtained following the administration of Gd-DTPA. Two patients in the study had an additional lesion in the liver (hemangioma and cholangiocarcinoma). Two patients had recurrence of a previously resected hepatocellular carcinoma. One patient had two studies but only the most recent was used. There were 18 male patients and six female patients with an average age of 51 years (range 18-71 years). All studies were performed with a 1.5-Tesla superconducting magnet (Signa; GE Medical Systems, Milwaukee, WI, USA) with standard hardware and software. Patients were imaged with at least two of the followingpulsing techniques: (1) Tl-weighted (T1W), (2) Tl-weighted with Gd-DTPA enhancement (TI W-E), (3) T2-weighted (T2W), (4) proton density (PD), and (5) gradient-recalled echoes (GRE). All of the patients had T1W images (TR 300-650 ms, TE 20 ms), 23 patients had PD images (TR 2022-3200 ms, TE 20-30 ms), 22 patients had T2W images (TR 2022-3200 ms, TE 80 ms), 20 patients had GRE images (20-45~ TR 25-50 ms, TE 13 ms), and nine patients had T1W-E images (TR 300-650 ms, TE 20 ms). All studies were performed using a body coil in the axial and coronal planes. Tenmillimeter slice thickness was used with a gap of 2 mm and a matrix of 128 x 128. The field of view varied from 32-40 cm. The number of excitations varied from 2-4. Gd-DTPA was administered intravenously to nine patients at a dose of 0.1 mmol/kg of
50
R.E. Rosenthal and P.L. Davis: Hepatocellular C a r c i n o m a
Table 1. Age, sex, n u m b e r of t u m o r s , size of largest tumor, and n u m b e r of tumors detected for each pulsing s e q u e n c e Patient no
Age (yr)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Sex
53 53 41 51 45 68 57 63 35 58 46 61 48 18 44 56 50 23 71 65 51 42 65 56
No. of tumors
M M F M M M M M M M M M M F M M F F M F M F M M
2 4 4 6 5 1 1 1 1 2 2 1 1 8 1 1 1 1 4 1 3 2 2 7
Size of largest tumor (cm) 7 4 3 8 14 2 10 3 9 2 8 14 1 20 14 3 4 14 7 14 4 5 8 5
N u m b e r of tumors detected TIW
T2W
PD
GRE
TIW-E
2 2 4 6 5 1 1 1 1 2 2 1 1 6 1 1 0 1 4 1 3 1 2 7
2 2 4 3 3 0 1 0 1 0 2
2 1 4 3 2 0 0 1 1 0 2
2 4 1 2 2 0 0 0 1 0
0 1
0 8 1
1 5 1 1 1 1 4 1 1 2 2 7
1 1 4 1 1 2 2 7
0
0 0 0 0
1
1 0 3 0
1 2 1
0 2 2
1
T1W, Tl-weighted; T2W, T2-weighted; PD, Proton density; GRE, Gradient-recalled echoes; T1W-E, T l - w e i g h t e d e n h a n c e d .
Table 2. Conspicuity of hepatocellular carcinomas by grading system Patient
T 1W
T2W
PD
GRE
4 2 3 4 5 4 4 5 2 3 3 2 4 3 3 1 1 2 3 4 3 2 2 2
3 3 3 3 4 1 3 1 4 1 1
2 1 2 2 3 1 1 4 2 1 1
1 4 1 1 2 1 1 1 1
3 4 5
1 2 2 1 3 4 4 1 1 4 2 3
T 1W-E
no.
1 2 3 4 5 6 7 8 9 10 ll 12 13 14 15 16 17 18 19 20 21 22 23 24
4 5 4 3 1 5 4 4
See Table 1 abbreviations.
1 5
body weight. I m a g e s were obtained immediately after the intraven o u s administration of G d - D T P A . T w o radiologists, who had prior knowledge of the pathological diagnosis, retrospectively reviewed all of the images, evaluating n u m b e r , size, and signal characteristics of the lesions. T h e images for each patient were ranked relative to each other for detectability of the lesion, from most difficult to easiest; the ranking was also based on the n u m b e r of pulsing techniques used. F o r example, if five pulsing techniques were used, then the images were ranked from 1 (for the most difficult) to 5 (for the easiest), but if two pulsing techniques were used, then the scoring range on the studies for that patient only went from 1 to 2. T h o s e studies using three and four pulsing techniques followed this ranking s y s t e m accordingly.
1
Results 1 1 1 1
4
1 1 1 1
2 2 4
1 1 1
3
Tables 1 and 2 are a summary of the data collected. Tumors ranged from !-20 cm in size and one to eight in number. According to our scoring system, T1W image were equal to T2W images for tumor detection. When the total number of lesions detected was counted, however, TIW images proved to be slightly better than T2W images. Images using the other pulsing techniques (PD, T1W-E, and GRE) detected fewer lesions. Figure 1 shows the usual signal characteristics of a hepatocellular carcinoma being diminished in signal intensity on T1W images and increased in signal intensity on T2W images. Figure 2
R.E. Rosenthal and P.L. Davis: Hepatocellular Carcinoma
Fig. 1. Hepatocellular carcinoma occupies entire left lobe of liver, most of anterior segment of right lobe of liver, and satellite lesions in posterior segment of right lobe of liver. A SE 700/20 axial image demonstrates diminished signal intensity and B SE 2800/80 axial image shows increased signal intensity. Fig. 2. Hepatocellular carcinoma with two lobulated masses in the right lobe of the liver with nonhomogenous increased signal intensity on both A SE 400/20 axial image and B SE 2500/80 axial image.
d e m o n s t r a t e s an atypical a p p e a r a n c e of eight hepatocellular c a r c i n o m a s (33%) that had nonhomogeneous increased signal intensity on both T1W and T2W pulsing techniques.
Discussion Hepatocellular c a r c i n o m a can be treated by surgical removal. M R I plays a crucial role in detecting and determining the full extent of this disease prior to surgery. Therefore, the o p t i m u m pulsing sequences should be used. In our research, detection of hepatocellular c a r c i n o m a was essentially equal on both T1W and T2W pulsing sequences. Other pulsing se-
51
quences (PD, G R E , and T I W - E ) were less effective. N e w experimental liver-contrast agents show promise in increasing the l i v e r - l e s i o n tissue contrast and this should increase detectability of tumors [6-11]. Various pathological findings that are specific for hepatocellular c a r c i n o m a have been found in MRI. This includes the p r e s e n c e of a pseudocapsule [3, 12-14], mosaic pattern [3, 13, 15], nodule within a nodule [16], and t u m o r t h r o m b u s in the portal vein [17]. In our series, one third (33%) of the hepatocellular carcinomas were hyperintense on both T1W and T2W images. We believe this pattern is atypical for m o s t other hepatic m a s s e s and hence can be used to suggest the mass is hepatocellular carcinoma. The increased signal intensity on T1W images has been reported in other articles [3, 14], but the rate of occurrence of increased signal intensity on both T1W and T2W pulse sequences has not been previously published. The increased signal intensity on both the T I W and T 2 W images is due to fatty metamorphosis in hepatocellular c a r c i n o m a [18]. Peters [19] has shown fat to be present in t u m o r cells that are well differentiated, because the fat is p r o d u c e d and not excreted. The m o s t c o m m o n entity that mimics hepatocellular c a r c i n o m a is a complicated cyst. This entity has hyperintensity on both T1W and T2W images
52
due to its high protein and hemorrhage content, but can be differentiated from hepatocellular carcinoma by its increased signal intensity consistent with fluid on T2W images. Other rare fatty tumors which should be included in the differential diagnosis include lipoma [20, 21], angiomyolipoma [21-24], adenoma [25], and myelolipoma [26]. To conclude, MRI with T1W and T2W pulse sequences are equal in detectability of hepatocellular carcinoma. Tumors in the liver with increased signal intensity on both TIW and T2W pulse sequences are highly suspicious for hepatocellular carcinoma. References 1. Barakos JA, Goldberg HI, Brown J J, Gilbert TJ. Comparison of computed tomography and magnetic resonance imaging in the evaluation of focal hepatic lesions. Gastrointest Radiol 1990;15:93-101 2. Doyle FH, Pennock JM, Banks LM, et al. Nuclear magnetic resonance imaging of the liver: initial experience. A JR 1982;138:193-200 3. ltoh K, Nishimura K, Togashi K, et al. Hepatocellular carcinoma: MR imaging. Radiology 1987;164:21-25 4. Moss AA, Goldberg HI, Stark DB, et al. Hepatic tumors: magnetic resonance and CT appearance. Radiology 1984;150:141-147 5. Vermess M, Leung AW-L, Bydder GM, Steiner RE, Blumgart LH, Young IR. MR imaging of the liver in primary hepatocellular carcinoma. J Comput Assist Tomogr 1985:9:749-754 6. Fretz C J, Elizondo G, Weissleder R, Hahn PF, Stark DD, Ferrucci JT. Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer. Radiology 1989;172:393-397 7. Marchal G, Van Hecke P, Demaerel P, et al. Detection of liver metastasis with superparamagnetic iron oxide in 15 patients: results of MR imaging at 1.5T. A JR 1989;152:771-775 8. Saini S, Stark DD, Hahn PF, et al. Ferrite particles: a superparamagnetic MR contrast agent for enhanced detection of liver carcinoma. Radiology 1987;162:217-222 9. Stark DD, Weissleder R, Elizondo G, et al. Superparamagnetic iron oxide: clinical application as a contrast agent for MR imaging of the liver. Radiology 1988;168:297-301 10. Thickman D, Hendrick RE, Jerjian KA, Schanker CS. Liver-
R.E. Rosenthal and P.L. Davis: Hepatocellular Carcinoma lesion tissue contrast on MR images: effect of iron oxide concentration and magnetic field strength. Radiology 1990;176:557-562 11. Tsang Y-M, Stark DD, Chen Mc-M, Weissleder R, Wittenberg J, Ferrucci JT. Hepatic micrometastases in the rat: ferrite-enhanced MR imaging. Radiology 1988;167:21-24 12. Ebara M, Obto M, Wantanabe Y, et al. Diagnosis of small hepatocellular carcinoma: correlation of MR imaging and tumor histologic studies. Radiology 1986; 159:371-377 13. Itai Y, Ohtomo K, Furui S, Minami M, Yoshikawa K, Yashiro N. MR imaging of hepatocellular carcinoma. J Cornput Assist Tomogr 1986;10:963-968 14. Rummeny E, Weissleder R, Stark DD, et al. Primary liver tumors: diagnosis by MR imaging. A JR 1989;152:63-72 15. Choi BI, Lee GK, Kim ST, Hart MC. Mosaic pattern of encapsulated hepatocellular carcinoma: correlation of magnetic resonance imaging and pathology. Gastrointest Radiol 1990;15:238-240 16. Mitchell DG, Rubin R, Siegelman ES, Burk DL, Rifkin MD. Hepatocellular carcinoma within siderotic regenerative nodules: appearance as a nodule within a nodule on MR images. Radiology 1991 ;178:101-103 17. Ohtomo K, Itai Y, Furui S, Yoshikawa K, Y.ashiro N, lio M. MR imaging of portal vein thrombus in hepatocellular carcinoma. J Comput Assist Tomogr 1985;9:328-329 18. Yoshikawa J, Matsui O, Takashima T, et al. Fatty metamorphosis in hepatocellular carcinoma: radiologic features in l0 cases. A JR 1988;151:717-720 19. Peters RL. Pathology of hepatocellular carcinoma. In: Okuda K, Peters RL, eds. Hepatocellular carcinoma. New York: Wiley, 1976:107-168 20. Ramchand S, Ahmed Y, Baskerville L. Lipoma of the liver. Arch Pathol 1970;90:331-333 21. Roberts JL, Fishman EK, Hartman DS, Sanders R, Goodman Z, Siegelman SS. Lipomatous tumors of the liver: evaluation with CT and US. Radiology 1986;158:613-617 22. Goodman ZD, Ishak KG. Angiomyolipomas of the liver. Am J Surg Pathol 1984;8:745-750 23. Pounder DJ. Hepatic angiomyolipoma. Am J Surg Pathol 1982;6:677-681 24. Kawarada Y, Mizumoto R. Angiomyolipoma of the liver. Am J Gastroenterol 1983;78:434-439 25. Angres G, Carter JB, Velasco JM. Unusual ring in liver cell adenoma. A JR 1980;135:172-174 26. Rubin E, Russinovich NAE, Luna RF, Tishler JMA, Wilkerson JA. Myelolipoma of the liver. Cancer 1984;54:2043-2046
Received: June 17, 1991; accepted: July 24, 1991
