Liver metastases: comparison of current MR techniques and spiral CT during arterial portography for detection in 20 surgically staged cases

Focal hepatic lesions: detection and characterization with combination gadolinium- and superparamagnetic iron oxide-enhanced MR imaging

PURPOSE

To compare gadolinium- and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for detection and characterization of focal hepatic lesions when different contrast agent administration sequences are used.

MATERIALS AND METHODS

Unenhanced, dynamic gadolinium-enhanced, and SPIO-enhanced hepatic MR images were obtained in 134 patients. SPIO-enhanced MR imaging was performed immediately after gadolinium-enhanced dynamic MR imaging in 50 patients, 1 day after gadolinium-enhanced dynamic MR imaging in 40 patients, and before gadolinium-enhanced dynamic MR imaging in 44 patients. Two radiologists independently reviewed the gadolinium image set (unenhanced and gadolinium-enhanced dynamic MR images) and the SPIO image set (unenhanced and SPIO-enhanced MR images) in random order. Lesion detection sensitivity and lesion characterization accuracy were compared by analyzing the area under the receiver operating characteristic curve (Az).

RESULTS

Overall lesion detection accuracy for pooled data was significantly higher with the SPIO set (Az = 0.903) than with the gadolinium set (Az = 0.857) (P <.05). When hypovascular lesions were excluded, the detection rate was similar with the two sets. When hepatocellular carcinomas were excluded, the detection rate was significantly higher with the SPIO set (P <.01). Readers were more accurate in differentiating benign from malignant lesions with the gadolinium set (Az = 0.915) than with the SPIO set (Az = 0.847) (P <.01). Detection accuracy tended to be better with the images obtained after the second contrast agent was used.

CONCLUSION

Hypovascular lesion detection was better with SPIO-enhanced MR images than with gadolinium-enhanced MR images. Detection and characterization of hypervascular lesions were improved with gadolinium-enhanced MR images.

Detection of colorectal liver metastases: a prospective multicenter trial comparing unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT

The aim of this study was to compare unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT in the detection of hepatic colorectal metastases. Forty-four patients with hepatic colorectal metastases were examined with unenhanced and MnDPDP-enhanced MRI and with unenhanced and contrast-enhanced spiral CT. The MR examination protocol included baseline T1-weighted spin-echo (SE), T1-weighted gradient-recalled-echo (GRE), and T2-weighted fast-SE sequences; and T1-weighted SE and T1-weighted GRE sequences obtained 30-60 min after administration of 0.5 micromol/kg (0.5 ml/kg) mangafodipir trisodium (MnDPDP). Images were interpreted by three blinded readers. Findings at CT and MRI were compared with those at intraoperative US, which were used as term of reference. Intraoperative US detected 128 metastases. In a lesion-by-lesion analysis, the overall detection rate was 71% (91 of 128) for spiral CT, 72% (92 of 128) for unenhanced MRI, and 90% (115 of 128) for MnDPDP-enhanced MRI. MnDPDP-enhanced MRI was more sensitive than either unenhanced MRI ( p<0.0001) or spiral CT ( p=0.0007). In a patient-by-patient analysis, agreement with gold standard was higher for MnDPDP-enhanced MRI (33 of 44 cases) than for spiral CT (22 of 44 cases, p=0.0023) and unenhanced MRI (21 of 44 cases, p=0.0013). MnDPDP-enhanced MRI is superior to unenhanced MRI and spiral CT in the detection of hepatic colorectal metastases.

Preoperative staging of colorectal cancer--computed tomography and magnetic resonance imaging

Cross-sectional imaging techniques are increasingly being used in the preoperative evaluation of patients with colorectal cancer. Both computed tomography (CT) and magnetic resonance (MR) imaging have been improved with significant advances of the technological hard- and software. This has contributed to high patient acceptance due to shorter examination times and more open configuration of the systems, consistent high quality images with better delineation of the normal abdomino-pelvic anatomy and pathology. New techniques such as CT-colonography have emerged from a research application to a clinical tool which can be used in different clinical settings. Phased-array receiver coils have significantly increased the usefulness of MR in the evaluation of rectal neoplasms due to the high resolution that can be obtained. New organ specific contrast agents for magnetic resonance imaging have facilitated the preoperative evaluation of liver metastases in favour of more invasive techniques with similar sensitivities. However, preoperative staging criteria for colorectal cancer using computed tomography and magnetic resonance imaging has to be updated and the results of new techniques have to be confirmed in large trials. In the future, further development of CT and MR may offer 'one-stop-shopping' protocols for both diagnosis, local and distant staging of colorectal cancer. Diffusion weighted MR-imaging, in vivo spectroscopy as well as further targeted imaging, such as with lymph node specific agents for MR may also prove to be helpful in the preoperative evaluation of patients with colorectal cancer.

Surgically staged focal liver lesions: accuracy and reproducibility of dual-phase helical CT for detection and characterization

PURPOSE

To assess the accuracy and reproducibility of dual-phase helical computed tomography (CT) in enabling preoperative detection and characterization of surgically staged focal liver lesions.

MATERIALS AND METHODS

Surgically and histopathologically proven liver lesions were evaluated by three experienced CT readers. These lesions were present in 77 patients who underwent dual-phase helical CT. Images were interpreted separately by the three blinded reviewers. Each lesion was graded on a nine-point scale of confidence, with 1 being definitely benign, 9 being definitely malignant, and 5 being indeterminate. The chi2 test was used to determine if the distribution of lesion classifications was different between readers.

RESULTS

There was a total of 237 lesions: 73 were benign and 164 were malignant. Sensitivity for lesion detection was 69%, 70%, and 71% for the three reviewers, respectively. Specificity was 91%, 86%, and 90%, and the area under the curve for the alternative-free response receiver operating characteristic curve was 0.84, 0.83, and 0.85, respectively. The difference in the distributions of lesion classification between the three reviewers was not statistically significant (P =.67) as determined by chi2 analysis.

CONCLUSION

Dual-phase CT has sensitivity of 69%-71% and high specificity (86%-91%) in enabling the detection and characterization of focal liver lesions. Interpretation is highly reproducible, as there is minimal variation between experienced reviewers.

Utility of sonography for small hepatic lesions found on computed tomography in patients with cancer

OBJECTIVE

To assess the performance of sonography in evaluating small indeterminate liver lesions detected on computed tomography in patients with cancer.

METHODS

Radiology database review from January 1, 1998, to August 4, 2000, identified 76 patients with 124 indeterminate hepatic lesions smaller than 1.5 cm on computed tomography who had abdominal sonography within 3 months. Sonographic reports and images were reviewed to assess whether lesions were referenced or specifically sought and to verify lesion correspondence, detection, and characterization. The validity of sonographic characterization was determined by histopathologic examination or follow-up imaging (mean time to follow up, 17 months; range, 6.5-38.8 months).

RESULTS

Sixty (48%) of 124 indeterminate lesions were evident on sonography. Detection improved when lesions were specifically sought and lesion size was greater than 0.5 cm. Forty (66%) of 61 lesions were detected when the radiologist referenced the preceding computed tomography versus 20 (32%) of 63 lesions when the computed tomographic findings were not referenced (P = .0004). Fifty-one (67%) of 76 lesions measuring 0.6 to 1.5 cm were detected on sonography versus 9 (19%) of 48 lesions measuring 0.1 to 0.5 cm. Lesion size (P < .0001) and body habitus (P = .02) were significant factors influencing lesion detection. Sonography characterized 56 (93%) of 60 detected lesions (33 cysts, 18 solid lesions/metastases, and 5 hemangiomas). Sonographic diagnoses were supported in 42 (93%) of 45 lesions by follow-up imaging (37 of 40) or histopathologic examination (5 of 5).

CONCLUSIONS

Sonography may be useful in cancer patients with average body habitus to characterize small (0.6- to 1.5-cm) indeterminate liver lesions detected on computed tomography.

Comparison of MR and PET imaging for the evaluation of liver metastases

PURPOSE

To compare the accuracy of fluoro-18-deoxyglucose positron emission tomography (FDG-PET) and dynamic-enhanced magnetic resonance imaging (MRI) scans in the diagnosis of liver metastatic lesions from colon and other sources.

MATERIALS AND METHODS

Thirty consecutive patients with known or suspected metastatic lesions were scanned by both MRI and PET. Histopathology and/or clinical outcome, including cross-sectional imaging follow up, were used as a gold standard.

RESULTS

Of 30 patients, 16 were positive by pathology and/or clinical outcome and 14 were negative for liver metastases. The sensitivity, specificity, and positive and negative predictive values on MRI were 85.7%, 100%, 100%, and 89%, respectively, compared to 71%, 93.7%, 90.9%, and 79% on FDG-PET. The difference between the two methods was not significant (X(2) = 0.2, P > 0.05).

CONCLUSION

Our study showed no significant difference in detection of liver metastases using MRI or FDG-PET. However, MRI has advantages in spatial resolution and lesion characterization.

Management of colorectal liver metastases

Hepatic metastases occur in 60% of patients following resection for colorectal cancer. Liver resection is the only curative option, with one third of resected patients alive at five years. In those developing recurrence in the liver following resection, further liver surgery may be curative, with similar 5 years survival rates of about 30%. Until recently surgery was feasible in only 15-25% of patients with colorectal liver metastases. New strategies, such as downstaging chemotherapy, portal vein embolization and two-stage hepatectomy, may increase the resectability rate by 15%. Earlier detection of liver metastases would increase resectability, although good follow-up trials are lacking. Once suspected, colorectal liver metastases are staged by spiral CT, CT portography and MRI, which have similar overall accuracies. Mortality following liver resection is less than 5% in major centres, with a morbidity rate of 20% to 50%. Prognostic scoring systems can be used to predict the likely cure rate with resection. Pulmonary metastases occur in 10-25% of patients with resected colorectal cancer, but are limited to the lung in only 2% of cases. In these selected cases surgery provides long-term survival in 20-40%, and repeat lung resection has shown similar rates. For patients with unresectable disease, chemotherapy and ablation techniques have been demonstrated to prolong survival, although chemotherapy alone has been shown to improve quality of life.

Diagnosis of hepatic neoplasms using CT arterial portography and CT hepatic arteriography

Both computed tomography arterial portography (CTAP) and CT hepatic arteriography (CTHA) are CT techniques with angiographic assistance. The detection sensitivity of these techniques is high because marked lesion contrast can be obtained using direct delivery of contrast materials to the liver parenchyma or the tumors. The use of CTAP and CTHA may improve therapeutic results after transarterial embolization therapy for hepatocellular carcinomas because of their high diagnostic accuracy. Findings on CTAP or CTHA can sometimes help characterize the hepatic focal lesions. Thus, CTAP and CTHA are frequently performed as pretreatment examinations, although they are invasive compared to intravenous (IV) contrast-enhanced CT or magnetic resonance imaging. However, there are some potential pitfalls, such as nontumorous perfusion abnormalities. CTAP and CTHA are less effective for evaluation of patients with cirrhosis and portal hypertension. This article presents a current overview of CTAP and CTHA technique for diagnosis of hepatic neoplasms.

Computed tomography and magnetic resonance imaging evaluation of liver cancer

Focal liver lesions occur commonly and with varying histology, each requiring radically different management. There are a multitude of imaging modalities currently being used for detecting and characterizing focal liver neoplasms. The primary modalities include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and rarely, angiography. CT and MRI have benefited from rapid technologic advances, and MRI, in particular, from the advent of new contrast agents.

Hepatic metastases in patients with colorectal cancer: relationship between size of metastases, standard of reference, and detection rates

PURPOSE

To determine the relationship between the size of hepatic metastases, the standard of reference, and the reported detection rate in patients with colorectal cancer.

MATERIALS AND METHODS

With use of a MEDLINE search (January 1994 to January 2001), articles were selected that contained original results on detection of hepatic metastases of colorectal cancer, categorized for size in at least two categories, with use of helical computed tomography (CT), helical CT at arterial portography, or magnetic resonance imaging. Results were compared with the size distribution of hepatic metastases in 47 consecutive patients with colorectal carcinoma, which were detected by using a combination of intraoperative ultrasonography (US) and palpation.

RESULTS

Seven studies met all predefined criteria. Four studies involved intraoperative US in all patients and demonstrated a significant negative correlation (-0.988) between detection rate and fraction of small metastases. These studies had a higher fraction and lower detection rate of small metastases and a lower overall detection rate. A majority (58% [145 of 252]) of metastases in the study population were smaller than 20 mm.

CONCLUSION

Few articles adequately describe the standard of reference and size distribution of hepatic lesions. Hepatic metastases of colorectal cancer are frequently smaller than 20 mm. When the standard of reference is suboptimal, many small metastases are excluded from analysis, and detection rates are therefore inflated.

Contrast agents for hepatic magnetic resonance imaging

The current availability of liver-specific contrast media (LSCM) allows the possibility to obtain an accurate diagnosis when studying focal liver lesions (FLL). It is necessary to have an in-depth knowledge of the biologic and histologic characteristics of FLL and the enhancement mechanism of LSCM to gain significant accuracy in the differential diagnosis of FLL. It is possible to subdivide FLL into three main groups according to the kinetics of contrast enhancement: hypervascular FLL, hypovascular FLL, and FLL with delayed enhancement. Dynamic contrast-enhanced magnetic resonance imaging is an important tool in the identification and characterization of FLL. LSCM with a first phase of extracellular distribution give both dynamic (morphologic) and late phase (functional) information useful for lesion characterization. With LSCM it is possible to differentiate with high accuracy benign from malignant lesions and hepatocellular from nonhepatocellular lesions. To understand contrast behavior after injection of LSCM, it is necessary to correlate contrast enhancement with the biologic and histologic findings of FLL.

Liver lesions: manganese-enhanced MR and dual-phase helical CT for preoperative detection and characterization comparison with receiver operating characteristic analysis

PURPOSE

The purpose of this study was to compare, by means of receiver operating characteristic (ROC) analysis, dual-phase helical computed tomography (CT) and manganese-enhanced magnetic resonance (MR) imaging in the detection and characterization of hepatic lesions in patients prior to surgery.

MATERIALS AND METHODS

Twenty-five patients known to have or suspected of having hepatic lesions who were eligible for surgery underwent dual-phase (ie, arterial and portal phase) helical CT and phased-array MR imaging (ie, unenhanced fast spin-echo T2-weighted imaging and gradient-echo T1-weighted imaging performed before and after administration of mangafodipir trisodium). All images were reviewed independently by three off-site blinded reviewers who separately reviewed the CT scans and MR images. The standard of reference was findings at surgery, intraoperative ultrasonography (US), and histopathologic examination. ROC curves were established to analyze the results for each reader and modality.

RESULTS

Ninety-four lesions (77 malignant and 17 benign) were revealed at surgery, intraoperative US, and/or histopathologic examination. The overall rate of lesion detection for the three readers at CT was 81.9% +/- 7.8, 90.4% +/- 5.9, and 76.6% +/- 8.6. At MR imaging, the detection rates were 72.3% +/- 9.0, 71.3% +/- 9.1, and 69.1% +/- 9.3 (P =.001 for the difference between MR and CT). The average rate of false-positive diagnoses in patients was 14.1% at CT and 6.4% at MR imaging (P =.06 for the difference between MR and CT). The mean areas under the alternative-free-response ROC curves were 0.74 for MR and 0.72 for CT (P =.751, not significant).

CONCLUSION

In detection and characterization of liver lesions, manganese-enhanced MR imaging and dual-phase helical CT were not statistically different.

MR imaging of the pediatric liver

Applications of MR imaging of the pediatric abdomen are expanding rapidly. New techniques of MR imaging, such as MRA or MRCP, are becoming commonplace. MR imaging is particularly helpful in the diagnosis and characterization of liver and biliary tree disease in children. Consistent and reproducible quality imaging is achieved with faster imaging sequences tailored to reduce motion artifacts. The lack of radiation, the ability to directly acquire multiple imaging planes, and the superior contrast resolution, particularly with the administration of gadolinium, have contributed to the acceptance of MR imaging as an invaluable tool in the pediatric age group.

MR imaging of hepatic metastases

MR imaging is an excellent diagnostic tool for the detection and characterization of liver metastases. The most characteristic finding is peripheral ring enhancement on immediate postgadolinium images.

MR imaging of benign hepatic tumors

Use of a state-of-the-art pattern recognition approach and the combination of various MR sequences and contrast enhancement techniques makes it possible to diagnose most benign hepatic tumors with confidence.

Computed tomography and magnetic resonance imaging of hepatic metastases

The detection and characterization of liver metastases is well performed with either computed tomography or magnetic resonance imaging. The administration of intravenous contrast is essential for almost all indications, with multiphasic imaging aiding in lesion characterization and detection. The use of multidetected CT (MDCT) provides the ability for optimized vascular and multiplanar imaging, but has also resulted in increased examination complexity. Tissue-specific MR contrast agents can yield the highest rate of lesion detection and thus may be useful in presurgical planning.

Detection of malignant hepatic tumors: comparison of gadolinium-and ferumoxide-enhanced MR imaging

OBJECTIVE

The purpose of our study was to compare how well gadolinium-enhanced and ferumoxide-enhanced MR imaging reveal malignant hepatic tumors.

SUBJECTS AND METHODS

Both gadolinium-enhanced and ferumoxide-enhanced MR imaging were separately performed in 53 patients with a total of 87 malignant hepatic tumors (57 hepatocellular carcinomas, 28 metastases, two cholangiocarcinomas). Thirty-one of the 53 patients had hepatic cirrhosis. Images were reviewed by three independent off-site observers. Observer performance was evaluated by means of sensitivity, specificity, and receiver operating characteristic curve analyses.

RESULTS

Gadolinium-enhanced MR imaging outperformed ferumoxide-enhanced MR imaging in sensitivity (81% versus 62%, p < 0.01) for malignant-tumor detection. Specificity was comparable (94%) between the two types of MR imaging. Area under receiver operating characteristic curve (A(z)) value was significantly higher with gadolinium-enhanced MR imaging than with ferumoxide-enhanced MR imaging in patients overall (A(z) = 0.896 versus 0.805, p < 0.001), in patients with cirrhosis (A(z) = 0.907 versus 0.807, p < 0.001), and in patients without cirrhosis (A(z) = 0.899 versus 0.834, p < 0.01). The superiority was enhanced in the subset of patients with cirrhosis.

CONCLUSION

Gadolinium-enhanced MR imaging outperforms ferumoxide-enhanced MR imaging in revealing malignant hepatic tumors. Gadolinium-enhanced MR imaging is recommended, particularly for patients with cirrhosis.

Hepatic metastases from colorectal cancer: preoperative detection and assessment of resectability with helical CT

PURPOSE

To prospectively evaluate helical computed tomography (CT) in the preoperative detection of hepatic metastases and assessment of resectability with surgical, intraoperative ultrasonographic (US), and histopathologic correlation.

MATERIALS AND METHODS

Between October 1995 and December 1998, preoperative staging with helical CT (5-mm collimation; reconstruction interval, 5 mm) was performed in 157 patients with hepatic metastases. Iodinated contrast material was injected intravenously (160-170 mL; rate, 2.5-3.0 mL/sec); acquisition began at 60-70 seconds. Four radiologists prospectively assessed the metastatic involvement of the liver by indicating the number and location of the lesions; resection was indicated in 113 patients (119 instances). Helical CT findings were correlated with pathologic and surgical findings on a lesion-by-lesion basis.

RESULTS

Intraoperative US, palpation, and histopathologic examination revealed 290 liver metastases; helical CT correctly depicted 247. Helical CT results were the following: overall detection rate, 85.1% (95% CI: 80.8%, 89.3%); positive predictive value, 96.1% (95% CI: 92.9%, 98.1%); and false-positive rate, 3.9% (10 of 257 findings; 95% CI: 1.9%, 7.1%). False-positive findings were related to hemangioendothelioma, hemangioma, hepatic peliosis, biliary adenoma, centrilobar hemorrhage, biliary hamartoma, periportal fibrosis, and normal liver parenchyma. Curative resection was performed in 112 instances with a resectability rate of 94.1%. Four-year patient survival rate was 58.6%.

CONCLUSION

Helical CT is a noninvasive, reliable, and accurate technique for imaging the liver and should be considered as the standard preoperative work-up of hepatic metastases from colorectal cancer.

Hepatic lesion detection and characterization: value of nonenhanced MR imaging, superparamagnetic iron oxide-enhanced MR imaging, and spiral CT-ROC analysis

PURPOSE

To determine the accuracy for detection and characterization of focal hepatic lesions of nonenhanced, superparamagnetic iron oxide (SPIO)-enhanced, or a combination of nonenhanced and SPIO-enhanced MR imaging and contrast-enhanced spiral computed tomography (CT).

MATERIALS AND METHODS

Spiral CT and T2-weighted SPIO-enhanced (ferucarbotran-enhanced) MR imaging were performed in 35 patients within 2 weeks before surgery for malignant hepatic lesions. Only malignant lesions with histopathologic proof were considered. A total of 875 images with and 800 images without focal lesions were presented to five readers, who were asked to assess the presence and characterization of lesions by using a five-point confidence scale. Receiver operating characteristic analysis was performed.

RESULTS

Nonenhanced and SPIO-enhanced images together and SPIO-enhanced images alone yielded the best performance for lesion detection. No differences were found among all imaging techniques with regard to lesion characterization (benign vs malignant). The combined approach resulted in larger area under the ROC curve (A(z) = 0.9062) and accuracy (85.3%) (P < 0.02), as compared with SPIO-enhanced MR imaging (A(z) = 0.8667; accuracy, 73.1%).

CONCLUSION

SPIO-enhanced T2-weighted MR imaging was more accurate than nonenhanced T1-weighted and T2-weighted MR imaging and contrast-enhanced spiral CT for the detection of focal hepatic lesions. The combined analysis of nonenhanced and SPIO-enhanced images was more accurate in the characterization of focal hepatic lesions than was review of SPIO-enhanced images alone.

Staging of colorectal cancer

CT, MR, and TRUS play complementary roles in staging CRC. Further improvements in these techniques will improve the accuracy of preoperative staging and thereby help optimize patient treatment and outcome.

Staging of advanced ovarian cancer: comparison of imaging modalities--report from the Radiological Diagnostic Oncology Group

PURPOSE

To compare ultrasonography (US), magnetic resonance (MR) imaging, and computed tomography (CT) for diagnosing and staging advanced ovarian cancer.

MATERIALS AND METHODS

US, CT, and MR imaging were performed in 280 patients. Images were read by three radiologists from each of the five hospitals. Image analysis included determination of malignancy within the peritoneum (11 sites), lymph nodes (10 sites), and hepatic parenchyma. The standard of reference was based on surgical and histopathologic findings. Statistical methods used were receiver operating characteristic (ROC) curve analysis, pairwise comparison of areas under the ROC curves (A(z)), analysis of sensitivity and specificity pairs, and assessment of agreement between the degree of suspicion and standard of reference.

RESULTS

There were 118 patients with malignant tumors; 73 (62%) had stage III or IV disease. Metastases were found in the peritoneum in 70 (59%), nodes in 20 (17%), and liver in seven (6%) cases. In the peritoneum, MR imaging and CT (A(z) = 0.96 for both) were more accurate than US (A(z) = 0.86), especially in the subdiaphragmatic spaces and hepatic surfaces. MR imaging and CT were more sensitive than US (95%, 92%, and 69%, respectively) for peritoneal metastases. MR imaging was more accurate than CT for detection of lymph node metastases (A(z) = 0.76 vs 0.57, P =.04). In the liver, the A(z) values for the three modalities were 0.77-0.94.

CONCLUSION

CT and MR imaging are equally accurate, and either modality can be used to stage advanced ovarian cancer.