Hepatic metastases studied with MR and CT

Effect of Interferon on T1 Relaxation Times of Liver Metastases from Endocrine Gastrointestinal Tumours

Eight patients with liver metastases from endocrine gastrointestinal tumours were examined with magnetic resonance imaging of the liver before and during treatment with interferon. T1, T2 and tumour size were measured and compared with tumour marker levels and symptomatic improvement or deterioration. Before therapy all tumours showed a long T1 and T2, in comparison to normal liver and fat, and during therapy they all showed a decrease in T1. As no change in liver T1 and fat T1 occurred, the decreased tumour T1 is considered to be a therapy effect. This cannot be fully explained but is possibly due to a reduction in tumour growth rate during interferon treatment. There was no certain correlation between tumour T1 and tumour marker levels or symptomatic changes.

Field-Echo Pulse Sequences Used under Suspended Respiration for Detection of Liver Metastases

To obtain a fast MRI sequence for detection of liver metastases under suspended respiration, two healthy volunteers were examined with the field echo sequence FLASH, using a large number of repetition times, echo times, flip angles and matrix sizes. The spleen was used to simulate liver metastases and contrast-to-noise ratios between liver and spleen were calculated and the sequence with the highest ratio was considered optimal. The different FLASH sequences were also compared with spin echo sequences using short repetition and echo times. A FLASH sequence with a repetition time of 140 ms, an echo time of 14 ms, a flip angle of 80 to 100 degrees and a matrix size of 128×256 was considered the most suitable for detecting liver metastases. This sequence, together with other FLASH and spin echo sequences, were used for examination of five patients with liver metastases from endocrine gastrointestinal tumours.

Hepatobiliary MR imaging with gadolinium-based contrast agents

The advent of gadolinium-based "hepatobiliary" contrast agents offers new opportunities for diagnostic magnetic resonance imaging (MRI) and has triggered great interest for innovative imaging approaches to the liver and bile ducts. In this review article we discuss the imaging properties of the two gadolinium-based hepatobiliary contrast agents currently available in the U.S., gadobenate dimeglumine and gadoxetic acid, as well as important pharmacokinetic differences that affect their diagnostic performance. We review potential applications, protocol optimization strategies, as well as diagnostic pitfalls. A variety of illustrative case examples will be used to demonstrate the role of these agents in detection and characterization of liver lesions as well as for imaging the biliary system. Changes in MR protocols geared toward optimizing workflow and imaging quality are also discussed. It is our aim that the information provided in this article will facilitate the optimal utilization of these agents and will stimulate the reader's pursuit of new applications for future benefit.

Resection of liver tumors: technical aspects

The resection of primary and secondary liver tumors has become accepted as the only curative therapy that can be offered to patients with these cancers. Technical advances made over the last two decades have improved the ability of the surgeon to perform these procedures with decreased morbidity. This article reviews hepatic anatomy, the preoperative evaluation of patients and various technical aspects involved in liver resections. The latter includes the role of intraoperative ultrasound and techniques of vascular occlusion and hepatic parenchymal dissection.

Accuracy of pathologic techniques for the diagnosis of metastatic melanoma in sentinel lymph nodes

BACKGROUND

Sentinel lymph node (SLN) biopsy can accurately predict the presence of metastatic melanoma (MM) and has been used to identify patients with occult metastases. We present an analysis of the sensitivity and specificity of standard pathological techniques including intraoperative frozen section, permanent section, and immunohistochemistry in diagnosing MM within the SLN.

METHODS

Sixty-nine consecutive patients with primary malignant melanoma thickness of >1.0 mm or thinner lesions invading the reticular dermis (Clark level IV) who underwent SLN biopsy were reviewed. Lymph nodes were examined intraoperatively by frozen section (FS), permanent section (H&E), and by immunohistochemistry (IH) for S-100 protein and HMB45.

RESULTS

MM was found in 14 of 69 cases (20%). Permanent section H&E was performed in all cases, FS in 64 cases, and IH in 65 cases. FS analysis diagnosed MM in 4 of 14 cases (29%), was suspicious in 2 of 14 (14%), and falsely negative (FN) in 8 of 14 (57%) ultimately found to be positive with further workup. Within the FN group, MM was identified on review of the original FS slides in 3 of 8 cases (38%). Furthermore, within the FN group, the remaining 5 cases were identified as positive for MM by either permanent and/or deeper H&E sections and IH. IH alone with permanent H&E sections would have diagnosed MM in only 8 of 10 cases (80%) that were FS negative or suspicious. In no cases was MM identified by IH alone with the permanent and deeper H&E sections being negative. It is noteworthy that no false-positive cases were identified.

CONCLUSIONS

Intraoperative FS has low sensitivity in identifying MM within the SLN. IH alone does not increase the diagnostic yield. A combination of permanent H&E sections with deeper levels and S-100 and HMB45 IH dramatically increases the overall diagnostic sensitivity of SLN biopsy. Definitive diagnosis should await permanent H&E sections and IH staining.

Hepatic tumor imaging using iron oxide MRI: comparison with computed tomography, clinical impact, and cost analysis

BACKGROUND

The surgical management of hepatic tumors has traditionally relied on preoperative contrast-enhanced computed tomography (CECT) in combination with intraoperative ultrasonography (IOUS). Unfortunately, the ability to detect and characterize hepatic tumors by using CECT is limited, and IOUS frequently reveals additional disease that alters the operative approach. Recent advances in hepatic magnetic resonance imaging (MRI) may improve preoperative tumor detection and characterization; however, little is known about how MRI compares with CECT or about the clinical impact and cost considerations of liver MRI.

METHODS

A retrospective chart review was performed to compare iron oxide (Feridex [Fe])-MRI with CECT in the preoperative imaging of hepatic neoplasms, as well as to determine the clinical impact and overall healthcare costs associated with Fe-MRI.

RESULTS

Of approximately 1000 patients who underwent abdominal MRI at a single institution during a 20-month period, 57 were identified who underwent Fe-MRI evaluation of the liver. Indications for imaging included suspected metastases (n = 43), an indeterminate hepatic mass (n = 9), or primary hepatic cancer (n = 5). Overall, Fe-MRI identified a total of 157 lesions (mean, 2.75 per patient; range, 0-14). CECT was performed in 50 patients, of whom 35 had primary or metastatic cancer. Fe-MRI identified more lesions than CT (n = 136 vs. 77; P = .016), and the average size of lesion detected by Fe-MRI was significantly smaller than that by CECT (2.5 vs. 3.4 cm; P = .018). Comparison of CECT and Fe-MRI findings with IOUS and pathological specimens showed a significant difference in sensitivity (MRI, 86%; CECT, 58%; P<.001), and IOUS changed the operative approach in only 5% of those imaged with Fe-MRI. Overall, Fe-MRI altered the clinical management in 67% of patients imaged (n = 38 of 57), which corresponded to an overall net cost savings of $108,368 ($1,901 per patient).

CONCLUSIONS

Fe-MRI is a powerful imaging technique, with greater hepatic tumor detection sensitivity than CECT. Moreover, it is an economically feasible imaging method that will alter the clinical management in most patients imaged.

Small hepatocellular carcinoma on magnetic resonance imaging. Relation of signal intensity to angiographic and clinicopathologic findings

RATIONALE AND OBJECTIVES

The authors discuss the clinicopathologic features and angiographic vascularity of various signal intensity patterns on magnetic resonance (MR) imaging of small hepatocellular carcinomas (HCCs).

METHODS

Magnetic resonance images of 88 resected HCCs (< or = 3 cm) were obtained using T1- and T2-weighted spin-echo images and T1-weighted images after gadolinium (Gd)-DTPA administration. Images were compared with angiographic and histopathologic findings.

RESULTS

Forty HCCs (45%) were depicted on T1-weighted images, 51 (58%) on T2-weighted images, and 41 (49%) on T1-weighted images after Gd-DTPA administration. Overall, 64 (76%) were found on at least one image. On T1-weighted images, hyperintense HCCs histologically showed fatty metamorphosis and portal tracts within the tumor. On T2-weighted images, HCC hyperintensity correlated with expansive growth, peliotic change, and hypervascularity. By contrast, HCCs that were undetected or hypointense on T2-weighted images were well differentiated with replacing growth and portal tracts. On T1-weighted images after Gd-DTPA, hyperintense HCCs had peliotic change; undetected HCCs were well differentiated and hypovascular.

CONCLUSIONS

Histologic grade, vascularity, portal tracts and peliotic change correlate with MR signal intensity. For hyperintense HCCs on T1-weighted images and hypo- or isointense HCCs on T2-weighted images, treatment methods must be assigned with the consideration that HCCs may be receiving transsinusoidal and portal blood supplies.

Fast MR imaging techniques: impact in the abdomen

The increased efficiency of MRI data acquisition has had a substantial impact on clinical MRI of the abdomen. Five particular applications that have thus been affected include breath-hold imaging of liver lesions (including detection, characterization, and biopsy), MR cholangiopan- creatography, practical chemical shift imaging (including liver and adrenal glands), dynamic imaging after contrast media injection, and MR angiography.

Preoperative evaluation of patients for liver resection. Appropriate CT imaging

OBJECTIVE

The authors determined which combination of computed tomography scans is most helpful for preoperative assessment of patients with liver tumors.

SUMMARY BACKGROUND DATA

Multi-institutional studies have shown that the most important prognostic factors for selection of patients with metastatic colorectal cancer considered for liver resection are: Dukes' stage of primary tumor, the number of hepatic metastases if greater than 3, the presence of extrahepatic cancer, and the ability to resect tumors with an adequate margin (> 1 cm.) Therefore the ability to predict the presence of extrahepatic disease and the number and location of hepatic tumors are important in these patients.

METHODS

One hundred and nine consecutive patients with evidence of hepatic tumors were evaluated by computed tomography with arterial portography (CTAP) and abdominal computed tomography after a 4-hour delay (CT-D). Results of these studies and conventional computed tomography (CT-C) were compared with findings at operation.

RESULTS

CTAP proved to be the most sensitive test for assessing distribution of intrahepatic disease. CT-D was no more sensitive than CT-C for the detection of hepatic or extrahepatic disease.

CONCLUSIONS

CT-C in concert with CTAP provides the most reasonable CT evaluation of patients considered for operation for the treatment of hepatic tumors.

Liver imaging at 1.5 tesla: pulse sequence optimization based on improved measurement of tissue relaxation times

In order to predict the most sensitive MR imaging sequence for detecting liver metastases at 1.5 T, in vivo measurements of T1 and T2 relaxation times and proton density were obtained using multipoint techniques. Based on these measurements, two-dimensional contrast contour plots were constructed demonstrating signal intensity contrast between hepatic lesions and surrounding liver parenchyma for different pulse sequences and pulse timing parameters. The data predict that inversion recovery spin echo (IRSE) imaging should yield the greatest contrast between liver metastases and liver parenchyma at 1.5 T, followed by short tau inversion recovery (STIR) and spin-echo (SE) pulse sequences. T2-weighted SE images provided greater liver/lesion contrast than T1-weighted SE pulse sequences. Calculated T1, T2, and proton density values of the spleen were similar to those of hepatic metastatic lesions, indicating that the signal intensity of the spleen may be used as an internal standard to predict the signal intensity of hepatic metastases on T1- and T2-weighted images at 1.5 T.

Comparison of computed tomography and magnetic resonance imaging in the evaluation of focal hepatic lesions

Two combined magnetic resonance (MR) spin-echo pulse sequences at 0.35 T were compared with dynamic bolus contrast-enhanced computed tomography (CT) in the evaluation of focal hepatic lesions. Each combined MR sequence was performed in a separate group of patients. The first group consisted of 76 patients in whom a moderately T1-weighted sequence (spin echo [SE] 500/30 [repetition time/echo time]) was combined with a T2-weighted sequence (SE 2000/60). In the second group, consisting of 68 patients, a more heavily T1-weighted sequence (SE 250/15) was combined with the T2-weighted sequence. All studies were evaluated in a retrospective blinded fashion, with construction of receiver operating characteristic curves. We conclude that, in detection of patients with one or more focal hepatic lesions, either combined MR sequence was comparable to CT. In the detection of individual hepatic lesions, the sensitivity of the combined MR sequence with a moderately T1-weighted sequence (SE 500/30 and 2000/60) was essentially equivalent to CT (79 vs 77%, respectively). Additionally, a combined MR sequence with a heavily T1-weighted pulse sequence (SE 250/15 and 2000/60) was not statistically different than CT (86 vs 80%, respectively). These findings were supported by the receiver operating characteristic analysis.

Comparison of lymphangiography and computed tomography scanning in evaluating abdominal disease in stages III and IV Hodgkin's disease. A Southwest Oncology Group study

The authors reviewed the records of 139 patients who had laparotomy plus computed tomography (CT) and/or lymphangiograms (LAG) as part of a their staging workup for Hodgkin's disease, in accordance with Southwest Oncology Group (SWOG) protocol 7808. They evaluated the relative ability of CT and LAG to detect disease in the abdomen. Two regions of the abdomen were designated, the upper and the lower, to further examine the capabilities of CT and LAG in the lower abdomen and CT in the upper abdomen. A LAG was more sensitive (P less than 0.05) than CT in detecting positive lower abdominal nodes. In the upper abdomen, CT scan had low sensitivity for detecting positive nodes, liver, or spleen. This study suggests that LAG of the lower abdomen provided more information than CT, and therefore should not be abandoned as a valid method for detecting nodal disease.

Comparative study between ultrasound, computed tomography, intra-arterial digital subtraction angiography, and magnetic resonance imaging in the differentiation of tumors of the liver

Forty-one patients with liver tumor have been evaluated with ultrasound (US), computed tomography (CT), intra-arterial digital subtraction angiography (IA-DSA), and magnetic resonance imaging (MRI) in order to establish the accuracy of each technique. In group A (24 patients), in which all four imaging modalities were performed, our results show that MRI detected all hemangiomas (25/25) compared to 22/25, 21/25, and 20/25 with US, CT, and IA-DSA, respectively. No difference between the various methods was seen in the case of hepatoma. Finally, in the patients with metastases, all four techniques had the same sensitivity (100%) but the specificity of MRI was also 100%, compared to 33% for IA-DSA and 66% for US and CT.

Bone and liver imaging in regionally advanced melanoma

The clinical records of 94 patients with regionally advanced melanoma (nodal disease or regional satellites) were reviewed to determine the value of preoperative bone and liver imaging. Of 68 bone scans obtained, none were suggestive of metastases. of 97 liver imaging studies (computed tomography, scintiscan, or sonography) in 88 patients, only two were found to have demonstrable metastases. Liver enzyme elevation was present in both of these patients. Bone and liver imaging in the absence of signs or symptoms of dissemination by history, physical examination, chest x-ray, and enzyme determination for regionally advanced melanoma appears to be of little value unless the patient is involved in a protocol study.

Are hepatic and muscle T2 values different at 0.5 and 1.5 Tesla?

In an effort to determine whether T2 values of liver and muscle change with increasing field strength, 144 abdominal MR examinations were retrospectively evaluated. These patients were evaluated with a dual echo T2-weighted spin-echo sequence. Eighty-two of the examinations were performed at 0.5 Tesla and 72 at 1.5 Tesla (T). Eleven of the patients were evaluated with both MR systems with the same sequences. T2 values were also obtained from a Fe NH4(SO4)2 12H2O phantom. The T2 values of liver decreased from 57.8 +/- 11.3 at 0.5 T to 43.7 +/- 8.3 at 1.5 T. The T2 values of muscle decreased from 44.2 +/- 9 at 0.5 T to 35.4 +/- 7.2 at 1.5 T. Patients who were examined on both systems also demonstrated a decrease in both liver and muscle T2 values. For concentrations in the range of hepatic T2's, the phantom demonstrated a decrease in T2 values from 0.5 to 1.5 T ranging from 20.3 to 23.4%. All the T2 changes were statistically significant (p less than .05). The findings suggest that T2 values may depend on field strength, or may vary due to other hardware-related differences.

Ultrasound, CT, and MRI comparison in primary and secondary tumors of the liver

Thirty-five patients with surgically removed or percutaneous biopsy-proven tumors were examined by ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). This retrospective study describes the appearance of the primary tumors and metastases and compares the sensitivity and specificity of the 3 imaging methods. Ultrasound, CT, and MRI examinations as well as clinical, operative, and/or histologic data were available for all 35 patients. Paramagnetic contrast agent gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was used in 23 patients and a short TI inversion recovery MRI sequence was used in 23 patients, in addition to various spin echo MRI sequences. Thirteen patients were examined using both Gd-DTPA and the short TI inversion recovery sequence. Our comparative study--based on the following criteria: detection, size, location of the tumor, and portal vein involvement and bile duct dilatation--demonstrated an advantage of MRI over ultrasound in 16 of 35 cases, equal results in 17 of 35 cases and a disadvantage of MRI compared to ultrasound in 2 of 35 cases. With the identical criteria, MRI proved to be more informative than CT in 10 of 35 cases, equal in 21 of 35 cases, and less informative in 4 of 35 cases.

Focal hepatic lesions: detection by dynamic and delayed computed tomography versus short TE/TR spin echo and fast field echo magnetic resonance imaging

Eighteen patients with focal hepatic lesions were evaluated with two computed tomographic (CT) techniques including dynamic sequential bolus contrast CT and delayed contrast CT, and 3 magnetic resonance (MR) techniques including a spin echo pulse sequence with TE/TR of 21/310 msec and 2 fast field echo sequences using a TE/TR of 15/300 msec and 80 degrees flip angle (T1-weighted) and TE/TR of 15/500 msec and 10-20 degrees flip angle (T2-weighted). We concluded that CT, using delayed contrast and dynamic sequential bolus contrast techniques, was consistently superior to the 3 MR pulse sequences used on our imagers in terms of number of lesions detected, lesion-to-liver contrast, and quality of scan.

Magnetic resonance imaging in the diagnosis of tumors of the liver

To evaluate the usefulness of magnetic resonance (MR) imaging in the diagnosis of liver tumors, MR imaging was performed in 70 patients, 30 with normal or cirrhotic liver, 15 with benign tumors and 25 with malignant tumors. MR imaging was carried out with a 0.5-Tesla superconducting magnet and was made using a spin-echo technique, from which T1 and T2-weighted images were obtained, and also T1 and T2 values were measured. Hemangiomas and cysts were demonstrated as sharply circumscribed homogeneous masses of low- or high-intensity on each image. Hepatomas were revealed as low-, iso- and high-intensity masses on both images. The minimum size of hepatoma detected, 1 cm in diameter, exhibited uniform intensity. Large hepatomas showed a mosaic pattern of different intensities, a low-intensity area around the mass, and a capsular pattern. The majority of metastatic tumors demonstrated a characteristic irregularity at the periphery of the mass. There were significant differences in T1 and T2 values between benign and malignant tumors. These results suggest that MR imaging is useful not only in the detection but also in the differentiation of liver tumors and can permit evaluation of the architecture of the tumor.

Evaluation of the gastrointestinal tract in the child: CT, MRI, and isotopic studies

The gastrointestinal radiologist no longer has to rely on indirect signs of extraluminal and solid organ pathology. With the use of the newer imaging modalities, including computed tomography, magnetic resonance imaging, and isotopic techniques, the entire abdomen and its contents can be directly visualized. Pathology, its extent and its effect on adjacent structures, can be readily appreciated.

Magnetic resonance imaging of the solitary hepatic mass: direct correlation with pathology and computed tomography

Magnetic resonance images (MRI) of the liver were obtained using a combination of short time inversion recovery (STIR) and spin echo (SE) sequences. These were correlated with comparable tissue slices generated from resected specimens obtained at partial hepatectomy. All 10 cases appeared to have solitary masses on contrast enhanced computed tomography (CT). Histological examination revealed five primary tumours (two hepatocellular carcinomas, two haemangiomas and one cholangiocarcinoma) and five metastatic tumours. The STIR images demonstrated a high signal intensity in all areas of viable tumour involvement and reduced signal intensity in regions of confluent necrosis with superimposed haemorrhage or calcification. This sequence also demonstrated additional areas of high signal intensity adjacent to several lesions which were not visible on CT. Microscopy of these regions in the specimens demonstrated no tumour involvement or steatosis and their precise cause remains obscure. All the lesions demonstrated on the CT images were visible on MRI and no additional lesions were discovered on detailed microscopical examination of the specimens. Delineation of the extent of the cholangiocarcinoma was a problem with both techniques. MRI showed no major advantage over CT except for a higher contrast of the lesion compared with normal liver and also a better delineation of the tumour mass.

Malignant tumors of the liver

HCC occurs infrequently in Western countries, with recent increases being reported in California and parts of Europe. Southeast Asia, Japan, and South Africa continue to have a high incidence of this tumor with HBV, cirrhosis, and the ingestion of aflatoxins being identified as probable risk factors. Although the majority of patients present with abdominal pain or mass indicative of extensive tumor, asymptomatic, small HCCs are being detected with increasing frequency. Early detection in high-risk individuals is best accomplished by screening with serum AFP determinations and liver ultrasonography. CT and arteriography are valuable preoperatively in defining anatomy and determining resectability. Five-year survival following resection for cure of HCC ranges from 20 to 40 per cent, with improved survival reported for small asymptomatic tumors. Resection of metastatic liver tumors from colorectal primaries results in 48 per cent 2-year and 24 per cent 5-year survivals, with an additional 5 per cent dying of recurrent cancer after 5 years. Although patients with simultaneous and metachronous metastases do equally well after resection, the presence of four or more individual deposits adversely affects survival. Hepatic artery ligation or embolization can produce a significant palliative reduction in total tumor mass in patients with unresectable liver metastases. Regional chemotherapy using implantable hepatic artery drug infusion pumps is promising, with reports of prolonged survival compared with historical controls. Regional hyperthermia, laser vaporization of tumor, and cryosurgical techniques may prove to have useful roles in the selective treatment of liver cancer in the future. Orthotopic liver transplantation has been successful primarily in those in whom the malignancy is found incidentally in the chronically diseased liver.