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

Incidence and predictors of synchronous liver metastases in patients with gastrointestinal stromal tumors (GISTs)

BACKGROUND

The liver is the most common metastatic site in patients with gastrointestinal stromal tumors (GISTs). The purpose of this study is to identify the incidence and predictive factors associated with synchronous liver metastases among patients with GISTs.

METHODS

A retrospective review of the Surveillance Epidemiology and End Results (SEER) database was performed.

RESULTS

Overall, 2757 patients were identified, of which 276 (10%) had synchronous liver metastases. The two-year survival of patients with synchronous liver metastases was 31.9% overall and 37.1% after undergoing surgery with curative intent. Primary tumor size >5 cm (5-10 cm: OR 2.97, 95% CI: 1.03-8.55, p = 0.044, >10 cm: OR 5.59, 95% CI: 1.95-16.07, p = 0.001), presence of nodal metastases (OR 4.09, 95% CI: 2.01-8.33, p < 0.001) and mitotic count >5/50 HPF (OR 1.58, 95% CI: 1.01-2.47, p = 0.044) were associated with the presence of liver metastases.

CONCLUSIONS

One out of ten patients with GISTs presents with hepatic metastases. Primary tumor size >5 cm, presence of nodal metastases and mitotic count >5/50 HPF are associated with a higher risk of synchronous hepatic metastases.

Resection of Colorectal Liver Metastases: Current Perspectives

BACKGROUND

Metastases to the liver is the leading cause of death in patients with colorectal cancer.

METHODS

The authors review the data on diagnosis and management of this clinical problem, and they discuss management options that can be considered.

RESULTS

Complete surgical resection of metastases from colorectal cancer that are localized to the liver results in 5-year survival rates ranging from 26% to 40%.

CONCLUSIONS

By adding modalities such as targeted systemic therapy and other "local" treatments for liver metastases, further gains in survival are anticipated.

Measurements of Hepatic Metastasis on MR Imaging:: Assessment of Interobserver and Intersequence Variability

RATIONALE AND OBJECTIVES

The purpose of the study was to investigate interobserver and intersequence variability in the measurement of hepatic metastasis on magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This retrospective study was conducted with an institutional review board-approved waiver of informed consent and was in compliance with the Health Insurance Portability and Accountability Act. We searched medical records at our institution for patients with histologically proven metastases to the liver who had undergone MRI from January 2008 to June 2010. We identified 20 patients with 30 measurable liver lesions. The liver lesions were measured on five different MRI sequences. A presenter radiologist selected and localized all metastatic lesions considered to be measurable according to the Response Evaluation Criteria in Solid Tumors, and these lesions were measured (Eisenhauer et al., 2009) by three radiologists independently. We calculated lesion-wise intraclass correlation coefficients (ICCs) to estimate interobserver and intersequence agreement in lesion diameter measurement. A Bland-Altman plot was used to estimate the limits of agreement between radiologists and MRI sequences.

RESULTS

There were 30 metastases, and almost all of which had regular and well-defined margins. Interobserver ICCs were greater than 0.95 for different MRI sequences except for the measurements in apparent diffusion coefficient images. Intersequence ICCs were greater than 0.92. Bland-Altman plots between physicians confirmed that reader measurements were closely tied together, with small differences in means.

CONCLUSIONS

MRI can reproducibly measure hepatic metastatic lesions without significant variability among interpreting radiologists or among MRI sequences, and is thus a reliable method for assessing the size of hepatic metastasis.

Hepatocellular carcinoma and other hepatic malignancies: MR imaging

Magnetic resonance (MR) imaging surpasses all other imaging modalities in characterizing liver lesions by virtue of the exquisite tissue contrast, specificity for various tissue types, and extreme sensitivity to contrast enhancement. In addition to differentiating benign from malignant lesions, MR imaging generally discriminates between the various malignant liver lesions. Hepatocellular carcinoma constitutes most primary malignant liver lesions and usually arises in the setting of cirrhosis. Intrahepatic cholangiocarcinoma is a distant second and features distinctly different imaging features. Overall, metastases are the most common malignant liver lesions and arise from several primary neoplasms; most commonly gastrointestinal, lung, breast, and genitourinary.

Contrast-enhanced ultrasound in the characterization of hepatocellular carcinomas treated by ablation: comparison with contrast-enhanced magnetic resonance imaging

The purpose of this study was to evaluate the clinical utility of low-mechanical-index contrast-enhanced ultrasound (CEUS) in assessing the response to percutaneous microwave ablation in patients with hepatocellular carcinoma by comparing the results with those of contrast-enhanced magnetic resonance imaging (CEMRI). Between August 2005 and July 2011, 182 patients with 231 lesions treated by microwave ablation were included in the study. One month after microwave ablation, CEUS and CEMRI were performed to evaluate therapeutic responses. The difference in diagnostic accuracy between the two methods was analyzed to evaluate the value of contrast-enhanced ultrasound after microwave ablation. The final diagnosis was based on computed tomography and MRI typical findings of therapeutic response of hepatocellular carcinoma, proven serum tumor marker levels and additional follow-up. The sensitivity of CEUS and CEMRI in evaluating the therapeutic effect of hepatocellular carcinoma was 86.5% and 84.6%; the specificity, 98.3% and 98.9%; and the accuracy, 95.7% and 95.7%.There was no significant statistical disparity between CEUS and CEMRI (p > 0.05).The sensitivity, specificity and accuracy were 98.1, 97.2 and 97.8% when CEUS was used in combination with CEMRI to evaluate the therapeutic response of hepatocellular carcinoma to microwave ablation. CEUS examination was proven to be a tolerable and easy modality for assessment of the therapeutic effect of microwave ablation and can provide results comparable to those obtained with CEMRI. Combining the results of these two examinations may reduce false-positive and false-negative diagnoses.

The Preoperative Assessment of Hepatic Tumours: Evaluation of UK Regional Multidisciplinary Team Performance

Introduction. In the UK, patients where liver resection is contemplated are discussed at hepatobiliary multidisciplinary team (MDT) meetings. The aim was to assess MDT performance by identification of patients where radiological and pathological diagnoses differed. Materials and Methods. A retrospective review of a prospectively maintained database of all cases undergoing liver resection from March 2006 to January 2012 was performed. The presumed diagnosis as a result of radiological investigation and MDT discussion is recorded at the time of surgery. Imaging was reviewed by specialist gastrointestinal radiologists, and resultswereagreedonby consensus. Results. Four hundred and thirty-eight patients were studied. There was a significant increase in the use of preoperative imaging modalities (P ≤ 0.01) but no change in the rate of discrepant diagnosis over time. Forty-two individuals were identified whose final histological diagnosis was different to that following MDT discussion (9.6%). These included 30% of patients diagnosed preoperatively with hepatocellular carcinoma and 25% with cholangiocarcinoma of a major duct. Discussion. MDT assessment of patients preoperatively is accurate in terms of diagnosis. The highest rate of discrepancies occurred in patients with focal lesions without chronic liver disease or primary cancer, where hepatocellular carcinoma was overdiagnosed and peripheral cholangiocarcinoma underdiagnosed, where particular care should be taken. Additional care should be taken in these groups and preoperative multimodality imaging considered.

Preoperative evaluation of colorectal liver metastases: comparison between gadoxetic acid-enhanced 3.0-T MRI and contrast-enhanced MDCT with histopathological correlation

OBJECTIVES

The aim of this prospective study was to compare the diagnostic performance of 64-row MDCT and gadoxetic-acid-enhanced MRI at 3.0 T in patients with colorectal liver metastases in correlation with histopathological findings.

METHODS

Lesions detected at MDCT and MRI were interpreted by three blinded readers and compared with histopathological workup as the term of reference. Two subgroups of lesions were additionally evaluated: (1) metastases smaller than 10 mm and (2) lesions in patients with and without steatosis of the liver, assessed histopathologically.

RESULTS

Surgery and histopathological workup revealed 81 colorectal liver metastases in 35 patients and diffuse metastatic involvement in 3 patients. In a lesion-by-lesion analysis, significant sensitivity differences could only be found for reader 1 (P = 0.035) and reader 3 (P = 0.003). For segment-based evaluation, MRI was more sensitive only for reader 3 (P = 0.012). The number of false-positive results ranged from 3 to 12 for MDCT and 8 to 11 for MRI evaluation. In the group of small lesions, the sensitivity differed significantly between both methods (P = 0.003). In patients with hepatic steatosis, MRI showed a trend toward better performance than MDCT, but without statistical performance.

CONCLUSIONS

The 3.0-T MRI with liver-specific contrast agents is the preferred investigation in the preoperative setting, especially for the assessment of small colorectal liver metastases.

KEY POINTS

• Potential surgical treatment requires accurate radiological assessment of colorectal liver metastases • Magnetic resonance imaging with gadoxetic acid is the preferred imaging investigation. • MRI is better than multidetector CT for detecting small liver metastases.

Selection for hepatic resection of colorectal liver metastases: expert consensus statement

Hepatic resection offers a chance of a cure in selected patients with colorectal liver metastases (CLM). To achieve adequate patient selection and curative surgery, (i) precise assessment of the extent of disease, (ii) sensitive criteria for chemotherapy effect, (iii) adequate decision making in surgical indication and (iv) an optimal surgical approach for pre-treated tumours are required. For assessment of the extent of the disease, contrast-enhanced computed tomography (CT) and/or magnetic resonance imaging (MRI) with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) is recommended depending on the local expertise and availability. Positron emission tomography (PET) and PET/CT may offer additive information in detecting extrahepatic disease. The RECIST criteria are a reasonable method to evaluate the effect of chemotherapy. However, they are imperfect in predicting a pathological response in the era of modern systemic therapy with biological agents. The assessment of radiographical morphological changes is a better surrogate of the pathological response and survival especially in the patients treated with bevacizumab. Resectability of CLM is dependent on both anatomic and oncological factors. To decrease the surgical risk, a sufficient volume of liver remnant with adequate blood perfusion and biliary drainage is required according to the degree of histopathological injury of the underlying liver. Portal vein embolization is sometimes required to decrease the surgical risk in a patient with small future liver remnant volume. As a complete radiological response does not signify a complete pathological response, liver resection should include all the site of a tumour detected prior to systemic treatment.

A comparative study of FDG PET/CT and enhanced multi-detector CT for detecting liver metastasis according to the size and location

PURPOSE

The aim of this study was to compare the diagnosability between (18)F-fluorodeoxyglucose (FDG) PET/CT and enhanced multi-detector CT (MDCT) for the detection of liver metastasis (LM) according to the size and location in liver and to evaluate standard maximum standardized uptake values (SUVmax) of all liver metastatic lesions.

MATERIALS AND METHODS

One hundred two consecutive patients with malignancy who underwent both FDG PET/CT and MDCT for LM evaluation were retrospectively reviewed. Among them, 56 patients with LM were enrolled in this study. LM was confirmed by follow-up imaging studies after at least 6 months or by histopathology. FDG PET/CT and MDCT images were visually analyzed using three-point scale by the consensus of two radiologists and two nuclear medicine physicians. The size and location (central vs. sub-capsular) of the all liver lesions were evaluated using MDCT images. Furthermore, SUVmax of all liver lesions on FDG PET/CT images were calculated.

RESULTS

A total of 146 liver lesions were detected by FDG PET/CT and MDCT and 142 of the lesions were diagnosed as LM. The detection rates of MDCT and FDG PET/CT for LM by visual analysis were 77 and 78%, respectively. There was no significant difference of detection rate according to the overall location and size of the lesions. However, FDG PET/CT was more sensitive than MDCT for detecting small and sub-capsular LM. The detection rate of FDG PET/CT for LM was 68% by the cutoff SUVmax of 2.7.

CONCLUSIONS

Although the diagnosabilities of MDCT and FDG PET/CT for detecting LM were comparable, FDG PET/CT is superior to MDCT for detecting small LM located in the sub-capsular portion of liver.

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.

Gadoxetic acid-enhanced 3.0 T MR imaging versus multidetector-row CT in the detection of colorectal metastases in fatty liver using intraoperative ultrasound and histopathology as a standard of reference

OBJECTIVE

To compare the diagnostic value of gadoxetic acid-enhanced MRI at 3.0 T with 64-row MDCT in the detection of colorectal liver metastases in diffuse fatty infiltration of the liver after neoadjuvant chemotherapy.

METHODS

Twenty-three patients with colorectal liver metastases and at moderate to severe steatosis (25-90%) underwent prospectively preoperative tri-phasic MDCT (Somatom Sensation 64, Siemens) and gadoxetic acid-enhanced MRI (3-T Magnetom Trio, Siemens). All patients underwent surgical resection of liver metastases. Intraoperative ultrasound (IOUS) was carried out, which served as the standard of reference, together with histopathology.

RESULTS

Overall, 68 metastases (range, 0.4-6 cm; 31/68 metastases [46%] ≤ 1 cm) were found at histology. MDCT detected 49/68 lesions (72%), and MRI 66/68 (97%, p < 0.001). For lesions ≤ 1 cm, MDCT detected only 13/31 (41.9%) and MRI 29/31 (93%, p < 0.001). Eight false-positive lesions were detected by MDCT, seven small lesions by MRI. There was no statistically significant difference between the two modalities in the detection of lesions > 1 cm (p = 0.250). IOUS detected all metastases and revealed two false-positive diagnoses.

CONCLUSION

Gadoxetic acid-enhanced 3.0 T MRI is superior to 64-row MDCT in detecting colorectal liver metastases ≤ 1 cm during preoperative staging in patients with liver steatosis. A combination of MRI and IOUS may further improve the outcome of surgical treatment.

Detection of liver metastases using gadoxetic-enhanced dynamic and 10- and 20-minute delayed phase MR imaging

PURPOSE

To assess the incremental value of hepatobiliary phase images in gadoxetate disodium-enhanced magnetic resonance imaging (MRI), and to compare diagnostic accuracy and lesion conspicuity on 10- and 20-minute delayed images for preoperative detection of hepatic metastases with subgroup analysis according to size and history of chemotherapy.

MATERIALS AND METHODS

Forty-six patients with 107 metastases who underwent surgery after gadoxetate disodium-enhanced MRI were evaluated. Four observers independently interpreted three sets: dynamic set comprising precontrast T1-, T2-weighted, and dynamic images; 10-minute set comprising dynamic set and 10-minute delayed; 20-minute set comprising 10-minute set and 20-minute delayed. Diagnostic accuracy was compared with subgroup analysis. Liver-to-lesion signal ratio (SR) was calculated using the region of interest method and compared.

RESULTS

Mean A(z) and sensitivities were significantly higher for 10- (A(z) = 0.894, sensitivity = 95.6%) and 20-minute (0.910, 97.2%) than dynamic set (0.813, 79.9%) (P < 0.001), with no significant difference between 10- and 20-minute sets (P = 0.140). In patients with small (≤1 cm) metastases and a history of chemotherapy, sensitivities were significantly higher with 10- (88.2%) and 20-minute (91.6%) sets than dynamic set (48.6%) (P < 0.001). SR was significantly higher for 10- and 20-minute delayed than precontrast and dynamic, with significantly higher SR on 20- than 10-minute delayed.

CONCLUSION

Regardless of size or prior chemotherapy, detection of hepatic metastases was significantly improved by adding hepatobiliary phase images without significant differences between 10- and 20-minute delayed.

Imaging diagnosis of colorectal liver metastases

Rapid advances in imaging technology have improved the detection, characterization and staging of colorectal liver metastases. Multi-modality imaging approach is usually the more useful in diagnosis colorectal liver metastases. It is well established that hepatic resection improves the long-term prognosis of many patients with liver metastases. However, incomplete resection does not prolong survival, so knowledge of the exact extent of intra-hepatic disease is crucially important in determining patient management and outcome. The diagnosis of liver metastases relies first and totally on imaging to decide which patients may be surgical candidates. This review will discuss the imaging options and their appropriate indications. Imaging and evaluating of colorectal liver metastases (CRLM) have been performed with contrast-enhanced ultrasound, multi-detector computed tomography, magnetic resonance imaging (MRI) with extra-cellular contrast media and liver-specific contrast media MRI, and positron emission tomography/computed tomography. This review will concentrate on the imaging approach of CRLM, and also discuss certain characteristics of some liver lesions. We aim to highlight the advantages of each imaging technique, as well as underscoring potential pitfalls and limitations.

MR-arterioportography: A new technical approach for detection of liver lesions

AIM: To evaluate the benefit and effectiveness of MR-arterioportography (MR-AP) to achieve the highest sensitivity for detection and evaluation of hepatocellular carcinoma (HCC).

METHODS: Twenty liver cirrhosis patients with suspected HCC were included before transarterial chemoembolization. In all patients double-enhanced Magnetic resonance imaging (MRI) was performed. A bolus of 10 mL Magnevist^® was injected through a selectively placed catheter in the superior mesenteric artery and MRI of the liver was performed in arterioportographic phase. Two independent readers evaluated number, size and localization of detected lesions. Diagnostic quality was determined using a 4-point scale. Differences were analyzed for significance using a t-test. Interobserver variability was calculated.

RESULTS: In all 20 patients (100%), MR-AP was feasible. Diagnostic quality was, in all cases, between 1 and 2 for both modalities and readers. MR-AP detected significantly more lesions than double-enhanced MRI (102.5 vs 61, respectively, P < 0.0024). The inter-observer variability was 0.881 for MRI and 0.903 for MR-AP.

CONCLUSION: Our study confirmed that the MR-AP as an additional modality for detection of HCC is beneficial, as significantly more lesions were detected compared to MRI with liver-specific contrast.

Assessment of liver metastases from colorectal adenocarcinoma following chemotherapy: SPIO-MRI versus FDG-PET/CT

PURPOSE

This study compared superparamagnetic iron-oxide-enhanced magnetic resonance imaging (SPIO-MRI) and combined fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) in evaluating liver metastases from colorectal adenocarcinoma following chemotherapy.

MATERIALS AND METHODS

Nineteen patients were included in this retrospective study. SPIO-MRI and PET/CT results were compared with surgery, intraoperative ultrasound and pathology results in 11 patients and with the follow-up in eight patients.

RESULTS

SPIO-MRI and PET/CT identified 125 and 71 metastases, respectively. False negative lesions were 11 for SPIO-MRI and 65 for PET/CT. In the whole study population, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 92% and 52% (p<0.001) and the per-segment analysis a sensitivity of 99% and 79% (p<0.001), respectively. In patients who underwent surgery, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 85% and 58% (p<0.05) and the per-segment analysis a sensitivity of 97% and 63% (p<0.05), respectively. In patients who underwent follow-up, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 97% and 47% (p<0.001) and the per-segment analysis a sensitivity of 100% and 63% (p<0.007), respectively. For lesions ≥15 and <30 mm and for lesions <15 mm, SPIO-MRI demonstrated a higher sensitivity than PET/CT (p<0.001).

CONCLUSIONS

SPIO-MRI appears superior to PET/CT in evaluating liver metastases from colorectal adenocarcinoma following chemotherapy.

Value of retrospective fusion of PET and MR images in detection of hepatic metastases: comparison with 18F-FDG PET/CT and Gd-EOB-DTPA-enhanced MRI

The purpose of this study was to compare the accuracy of lesion detection and diagnostic confidence between (18)F-FDG PET/CT, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI, and retrospectively fused PET and MRI (PET/MRI).

METHODS

Thirty-seven patients (mean age +/- SD, 60.2 +/- 12 y) with suspected liver metastases underwent PET/CT and Gd-EOB-DTPA-enhanced MRI within 0-30 d (mean, 11.9 +/- 9 d). PET and Gd-EOB-DTPA-enhanced MR image data were retrospectively fused. Images were reviewed independently by 2 readers who identified and characterized liver lesions using PET/CT, Gd-EOB-DTPA-enhanced MRI, and PET/MRI. Each liver lesion was graded on a 5-point confidence scale ranging from definitely benign (grade of 1) to definitely malignant (grade of 5). The accuracy of each technique was determined by receiver-operating-characteristic analysis. Histopathology served as the standard of reference for all patients with malignant lesions.

RESULTS

A total of 85 liver lesions (55 liver metastases [65%] and 30 benign lesions [35%]) were present in 29 (78%) of the 37 patients. Twenty-four (65%) of the 37 patients had liver metastases. The detection rate of liver lesions was significantly lower for PET/CT than for Gd-EOB-DTPA-enhanced MRI (64% and 85%; P = 0.002). Sensitivity in the detection and characterization of liver metastases for PET/CT, Gd-EOB-DTPA-enhanced MRI, PET/MRI in reader 1, and PET/MRI in reader 2 was 76%, 91%, 93%, and 93%, respectively; the respective specificity values were 90%, 100%, 87%, and 97%. The difference in sensitivity between PET/CT and PET/MRI was significant (P = 0.023). The level of confidence regarding liver lesions larger than 1 cm in diameter was significantly higher in PET/MRI than in PET/CT (P = 0.046). Accuracy values (area under the receiver-operating-characteristic curve) for PET/CT, Gd-EOB-DTPA-enhanced MRI, PET/MRI in reader 1, and PET/MRI in reader 2 were 0.85, 0.94, 0.92, and 0.96, respectively.

CONCLUSION

The sensitivity of Gd-EOB-DTPA-enhanced MRI and PET/MRI in the detection of liver metastases is higher than that of PET/CT. Diagnostic confidence was significantly better with PET/MRI than with PET/CT regarding lesions larger than 1 cm in diameter. Compared with Gd-EOB-DTPA-enhanced MRI, PET/MRI resulted in a nonsignificant increase in sensitivity and diagnostic confidence.

Preoperative detection of colorectal liver metastases in fatty liver: MDCT or MRI?

OBJECTIVE

To compare the diagnostic value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative detection of colorectal liver metastases in diffuse fatty infiltration of the liver, associated with neoadjuvant chemotherapy.

MATERIALS AND METHODS

Twenty preoperative tri-phasic MDCT (4-64-row, Siemens) and dynamic contrast-enhanced MRI (1.5T or 3.0T, Siemens) examinations of patients with colorectal cancer and liver metastases in diffuse steatosis were retrospectively evaluated. All patients underwent surgical resection for liver metastases (time interval 1-60 days). The amount of fatty infiltration of the liver was determined histopathologically by semi-quantitative percent-wise estimation and ranged from 25 to 75%.

RESULTS

Overall, 51 metastases were found by histopathology of the resected liver segments/lobes. The size of the metastases ranged from 0.4 to 13 cm, with 18 (35%) being up to 1cm in diameter. In the overall rating, MDCT detected 33/51 lesions (65%), and MRI 45/51 (88%). For lesions up to 1cm, MDCT detected only 2/18 (11%) and MRI 12/18 (66%). One false positive lesion was detected by MDCT. Statistical analysis showed that MRI is markedly superior to MDCT, with a statistically significant difference (p<.001), particularly for the detection of small lesions (≤ 1 cm; p<.004). There was no significant difference between the two modalities in the detection of lesions>1cm.

CONCLUSION

For the detection of colorectal liver metastases after neoadjuvant chemotherapy and consecutive diffuse fatty infiltration of the liver, MRI is superior to MDCT, especially for the detection of small lesions.

Triple-phase computed tomography during arterial portography with bolus tracking for hepatic tumors

PURPOSE

The purpose of this study was to assess the usefulness of triple-phase computed tomography during arterial portography (CTAP) using a bolus-tracking technique.

MATERIAL AND METHODS

The subjects were 60 patients with hepatic tumors: 20 patients with metastatic liver tumors with a normal liver and 40 with hypervascular hepatocellular carcinoma (HCC) with liver cirrhosis. The region of interest was set in the portal vein, and CTAP was automatically started after the triggering threshold (180 HU) was reached. Three scans were performed: early phase (E), hepatic parenchymal phase (HP), and late phase (L). The scan start time of E-CTAP was measured. The detection rates of the HCC nodules were evaluated during each CTAP phase.

RESULTS

CTAP was performed by bolus tracking without failure in any of the patients. The mean scan start times in the normal liver group and liver cirrhosis group were 14.3 +/- 1.34 s and 18.5 +/- 2.46 s, respectively, which were significantly different from each other. The detection rates of HCC nodules for E-CTAP, HP-CTAP, and L-CTAP were 29.6%, 100%, and 83.3%, respectively.

CONCLUSION

The bolus-tracking technique enabled us to perform CTAP with optimal timing regardless of the portal blood flow dynamics.

Magnetic resonance imaging of the liver: New imaging strategies for evaluating focal liver lesions

The early detection of focal liver lesions, particularly those which are malignant, is of utmost importance. The resection of liver metastases of some malignancies (including colorectal cancer) has been shown to improve the survival of patients. Exact knowledge of the number, size, and regional distribution of liver metastases is essential to determine their resectability. Almost all focal liver lesions larger than 10 mm are demonstrated with current imaging techniques but the detection of smaller focal liver lesions is still relatively poor. One of the advantages of magnetic resonance imaging (MRI) of the liver is better soft tissue contrast (compared to other radiologic modalities), which allows better detection and characterization of the focal liver lesions in question. Developments in MRI hardware and software and the availability of novel MRI contrast agents have further improved the diagnostic yield of MRI in lesion detection and characterization. Although the primary modalities for liver imaging are ultrasound and computed tomography, recent studies have suggested that MRI is the most sensitive method for detecting small liver metastatic lesions, and MRI is now considered the pre-operative standard method for diagnosis. Two recent developments in MRI sequences for the upper abdomen comprise unenhanced diffusion-weighted imaging (DWI), and keyhole-based dynamic contrast-enhanced (DCE) MRI (4D THRIVE). DWI allows improved detection (b = 10 s/mm²) of small (< 10 mm) focal liver lesions in particular, and is useful as a road map sequence. Also, using higher b-values, the calculation of the apparent diffusion coefficient value, true diffusion coefficient, D, and the perfusion fraction, f, has been used for the characterization of focal liver lesions. DCE 4D THRIVE enables MRI of the liver with high temporal and spatial resolution and full liver coverage. 4D THRIVE improves evaluation of focal liver lesions, providing multiple arterial and venous phases, and allows the calculation of perfusion parameters using pharmacokinetic models. 4D THRIVE has potential benefits in terms of detection, characterization and staging of focal liver lesions and in monitoring therapy.

A diagnostic paradigm for resectable liver lesions: to biopsy or not to biopsy?

BACKGROUND

Despite a growing body of evidence reporting the deleterious mechanical and oncological complications of biopsy of hepatic malignancy, a small but significant number of patients undergo the procedure prior to specialist surgical referral. Biopsy has been shown to result in poorer longterm survival following resection and advances in modern imaging modalities provide equivalent, or better, diagnostic accuracy.

METHODS

The literature relating to needle-tract seeding of primary and secondary liver cancers was reviewed. MEDLINE, EMBASE and the Cochrane Library were searched for case reports and series relating to the oncological complications of biopsy of liver malignancies. Current non-invasive diagnostic modalities are reviewed and their diagnostic accuracy presented.

RESULTS

Biopsy of malignant liver lesions has been shown to result in poorer longterm survival following resection and does not confer any diagnostic advantage over a combination of non-invasive imaging techniques and serum tumour markers.

CONCLUSIONS

Given that chemotherapeutic advances now often permit downstaging and subsequent resection of 'unresectable' disease, the time has come to abandon biopsy of solid lesions outside the setting of a specialist multi-disciplinary team meeting (MDT).

The clinical impact of magnetic resonance imaging in diagnosing focal hepatic lesions and suspected cancer

AIMS

To compare the clinical utility of contrast enhanced magnetic resonance imaging (MRI) to ultrasound (USS) and computed tomography (CT) in focal hepatic lesions (FHLs)

METHODS

This retrospective study analysed 125 consecutive iron oxide enhanced (SPIO) MRI.

RESULTS

MRI made a difference in 74% of patients who had USS and in 42% of patients who had a CT scan. In suspected cancer, MRI changed diagnosis in 58% and 37% (13/35), respectively.

CONCLUSIONS

MRI is superior to other noninvasive imaging modalities for lesion identification and characterisation.

Continuously moving table MRI with sliding multislice for rectal cancer staging: image quality and lesion detection

PURPOSE

To determine image quality and lesion detection of sliding multislice (SMS), a recently developed moving table MRI technique, in patients with rectal cancer.

MATERIALS AND METHODS

Twenty-seven paired SMS (Avanto, Siemens Medical Solutions) and MDCT (Sensation 64, Siemens Medical Solutions) examinations of abdomen and pelvis were performed in patients with rectal cancer and compared for detection of liver, lymph node and bone metastases by two independent observers. A contrast-enhanced, fat saturated 2D gradient echo sequence (TE, 2.0 ms; TR, 102 ms; slice, 5 mm) was acquired with SMS and a standard contrast-enhanced protocol (100 ml @ 2.5 ml/s; slice, 5 mm) was used for abdominal MDCT. Standard of reference consisted of a consensus evaluation of SMS, MDCT, and all available follow-up examinations after a period of 6 months. Artifact burden and image quality of SMS was assessed in comparison to stationary gradient echo sequences obtained in an age-matched group of 27 patients.

RESULTS

Whereas SMS achieved a mean quality score of 3.65 (scale, 0-4) for the liver, representing very good diagnostic properties, strong breathing artifacts in the intestinal region were observed in 19 cases by both observers. The retroperitoneum still achieved a mean quality score of 3.52, although breathing artifacts were noted in 12 and 15 cases (observers 1 and 2, respectively). The sensitivities of SMS to detect hepatic metastases were 91.2% and 94.1% for both observers, respectively, compared to 98.5%/98.5% for MDCT. The sensitivities for lymph node metastases were 87.5%/81.3% for SMS compared to 78.1%/81.3% for MDCT. The sensitivities for bone metastases were 91.7%/100% for SMS compared to 8.3%/16.7% for MDCT.

CONCLUSION

With slightly reduced image quality in the intestinal region, SMS exhibits equal detection of lymph node and liver metastases compared to MDCT. SMS MRI proved to be superior to MDCT in detection of bone metastases.

Preoperative imaging for metastasectomy

For most solid neoplasms, medical imaging is a vital component of tumor staging and surveillance. Imaging strategies vary according to the type and grade of primary neoplasm, tumor stage at diagnosis, tumor markers, previous therapies, and patient symptoms. In this article, we address imaging of individual organs (lung, liver, adrenals) and outline imaging strategies for specific types of neoplasms.

Diagnosis and treatment of metastatic disease to the liver

A number of cancers present with synchronous or metachronous hepatic metastases. Historically, many of these patients were considered unresectable and were treated with either systemic chemotherapy or supportive care. Today, a variety of options exist for the management of hepatic metastases. Newer agents for systemic therapy continue to be introduced and are providing improved progression-free and overall survival and increased resectability of liver metastases. However, complete surgical resection of isolated hepatic metastases remains the optimal management for these patients. Surgical interventions can be offered to patients with hepatic-only metastases. Hepatic artery chemotherapy represents an adjunct for those patients undergoing resection and can improve survival. This benefit may be even more pronounced when combined with systemic chemotherapy. Newer generation biologic agents can improve results. New therapeutic modalities to treat lesions that are unresectable include ablative techniques such as radiofrequency ablation (RFA) and cryoablation. This article will examine modalities of diagnosis of hepatic metastases and highlight the data regarding hepatic resection for metastases of several types of primary cancers, the rationale for, and efficacy of, hepatic arterial chemotherapy, in both the postoperative adjuvant setting and in unresectable liver disease, and review the current literature for ablative techniques in the treatment of liver metastases.

Sensitivity of magnetic resonance imaging in the detection of colorectal liver metastases

INTRODUCTION

The aim of this study was to evaluate the sensitivity of magnetic resonance imaging (MRI) in the detection of colorectal liver metastases.

PATIENTS AND METHODS

Pre-operative MRI scanning of the liver was performed by a single radiologist and the size and number of definite liver metastases were recorded. Patients then underwent hepatectomy with routine intra-operative ultrasonography (IOUS) and resected specimens were sent for histopathology. Pathology findings were compared with those of MRI scans to determine the sensitivity of this imaging modality. Exclusions were patients undergoing hepatic resection more than 4 weeks after the MRI scan, those undergoing chemotherapy at the time of the scan, and those with conglomerate unilobar metastases.

RESULTS

Complete data were available for 84 patients. There was total agreement between MRI, IOUS and histology in 79 patients (101 metastases). MRI missed 5 metastases in 5 patients that were found on IOUS (or palpation of superficial lesions) and subsequently confirmed by histological examination. These measured 5 mm or less (4 patients) and 7 mm (one patient). The sensitivity of MRI in the detection of colorectal liver metastases was thus 94% for all lesions and 100% for lesions 1 cm or larger in diameter.

CONCLUSIONS

MRI of the liver is a non-invasive technique with an extremely high degree of sensitivity in the detection of colorectal liver metastases and should be considered as the 'gold standard' in the pre-operative imaging of these patients.

Detection of hepatic metastases from colorectal carcinoma: comparison of histopathologic features of anatomically resected liver with results of preoperative imaging

GOALS

The specificity and sensitivity of intravenous-enhanced multidetector row computed tomography (MDCT), superparamagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI), multidetector row computed tomography with arterioportography combined with multidetector row computed tomography with hepatic arteriography (CTAP/CTHA), and intraoperative ultrasonography (IOUS) for detecting hepatic metastases from colorectal carcinoma were evaluated based on histopathologic examination of resected livers.

STUDY

MDCT, SPIO-MRI, CTAP/CTHA, and IOUS were performed routinely to determine surgical indications and methods in patients with hepatic metastases from colorectal carcinoma. The resected liver specimens were then cut serially into sections 3 to 5 mm thick for routine histologic examination.

RESULTS

Fifty metastatic lesions were detected by histopathologic study of a large amount of anatomically resected liver from 8 patients with colorectal liver metastasis. The tumors ranged in size from 3 to 53 mm (mean 13.8 mm) and 26 lesions (52%) were less than 10 mm in diameter. Histopathologic examination of the resected liver specimens showed that CTAP/CTHA was the most sensitive imaging modality, followed in order by IOUS, SPIO-MRI, and MDCT. Among all the tumors detected by CTAP/CTHA, SPIO-MRI overlooked 5, but all of the tumors detected by SPIO-MRI were also detected by CTAP/CTHA. The number of metastatic liver tumors detected differed significantly among MDCT, SPIO-MRI, and histopathologic examination. One false-positive lesion was detected by IOUS.

CONCLUSIONS

CTAP/CTHA is a useful preoperative imaging modality for detecting small hepatic metastases from colorectal carcinoma.

Imaging of liver metastases: MRI

Metastases are the most common malignant liver lesions and the most common indication for hepatic imaging. Specific characterization of liver metastases in patients with primary non-hepatic tumors is crucial to avoid unnecessary diagnostic work-up for incidental benign liver lesions. Magnetic resonance (MR) is rapidly emerging as the imaging modality of choice for detection and characterization of liver lesions due to the high specificity resulting from optimal lesion-to-liver contrast and no radiation exposure. Improvements in breath-hold T1-weighted fast spoiled gradient echo and rapid T2-weighted single shot echo-train acquisition enable imaging of the liver in a single breath-hold with high spatial resolution. Most metastases are hypo- to isointense on T1 and iso- to hyperintense on T2-weighted images. MR contrast agents provide critical tumor characterization and can be safely used in patients with iodine contrast allergy and renal failure. Other agents, including newly developing gadolinium-chelates or iron oxide agents may provide additional benefits in selected applications. The degree and nature of tumor vascularity form the basis for liver lesion characterization based on enhancement properties. Liver metastases may be hypovascular or hypervascular. Colon, lung, breast and gastric carcinomas are the most common tumors causing hypovascular liver metastases, and typically show perilesional enhancement. Neuroendocrine tumors including carcinoid and islet cell tumors, renal cell carcinoma, breast, melanoma, and thyroid carcinoma are tumors most commonly causing hypervascular hepatic metastases, which may develop early enhancement with variable degrees of washout and peripheral rim enhancement.

Radiological staging of colorectal liver metastases

Rapid advances in imaging technology have improved the detection, characterization and staging of colorectal liver metastases. Multi-modality imaging approach is usually the more useful in staging colorectal liver metastases. Multi-detector computed tomography (MDCT) remains the main imaging modality for preoperative planning, lesion detection and tumour surveillance. Magnetic resonance imaging (MRI) and contrast enhanced ultrasonography (US) are invaluable in problem solving for characterization indeterminate lesions, while contrast enhanced intra-operative ultrasound (CE-IOUS) may be the new gold standard staging tool prior to liver resection. Ultimately, the imaging strategy has to be tailored to the clinical situation to obtain the most relevant information for optimal use of available imaging resources.

Evaluation of a Novel Time-Efficient Protocol for Gadobenate Dimeglumine (Gd-BOPTA)-Enhanced Liver Magnetic Resonance Imaging

OBJECTIVE

We sought to evaluate gadobenate dimeglumine for the detection and characterization of focal liver lesions in the unenhanced and already pre-enhanced liver.

MATERIALS AND METHODS

Sixty patients were evaluated prospectively. Unenhanced T1-weighted gradient echo (T1wGRE) and T2-weighted turbo spin echo (T2wTSE) images were acquired followed by contrast-enhanced T1wGRE images during the dynamic, equilibrium, and delayed phases after the bolus injection of 0.05 mmol/kg gadobenate dimeglumine. An identical series of dynamic images was then acquired after the delayed scan following a second 0.05 mmol/kg bolus of gadobenate dimeglumine. Images were evaluated randomly in 2 sessions by 3 independent blinded readers. Evaluated images in the first session comprised the unenhanced images, the first or second set of dynamic images, and the delayed images. The second session included the unenhanced images, the dynamic images not yet evaluated in the first session, and the delayed images. The 2 reading sessions were compared for lesion characterization and diagnosis, and kappa (kappa) values for interobserver agreement were determined. Quantitative evaluation of lesion contrast enhancement was also performed.

RESULTS

The enhancement behavior in the second dynamic series was similar to that in the first series, although pre-enhancement of the normal liver resulted in reduced lesion-liver contrast-to-noise ratios and the visualization of some lesions only on arterial phase images. Typical imaging features for the lesions included in the study were visualized clearly in both series. Strong agreement (kappa=0.56-0.89; all evaluations) between the 2 images sets was noted by all readers for differentiation of benign from malignant lesions and for definition of specific diagnosis, and between readers for diagnoses established based on images acquired in the unenhanced and pre-enhanced liver.

CONCLUSION

Dynamic imaging in the hepatobiliary phase gives similar information as dynamic imaging of the unenhanced liver. This might prove advantageous for screening protocols involving same session imaging of primary extrahepatic tumors and liver.

The role of SPIO-enhanced MRI in the detection of malignant liver lesions

The aim of this study was to evaluate the efficacy of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the detection of malignant liver tumors. MRI, using fast spin-echo T(2)-weighted and gradient-echo T(1)-weighted imagings before and after SPIO infusion, was performed in 32 patients with known or suspected hepatic lesions. Statistical analysis was performed using lesion-by-lesion analysis. SPIO-enhanced T(2)-weighted MRI showed results comparable to those of unenhanced T(2)-weighted MRI in the detection of focal liver lesions.

Accuracy of single phase contrast enhanced multidetector CT colonography in the preoperative staging of colo-rectal cancer

AIM

The optimal acquisition time for staging colo-rectal carcinoma with a contrast enhanced multidetector CT colonography (CE CTC) has not yet been established. A dual phase with both arterial and portal venous acquisition has been proposed. The purpose of our study is to assess the value of single portal venous phase CE CTC in the preoperative staging of colo-rectal carcinoma.

MATERIALS AND METHODS

Fifty two (30 M, 22 F; aged 35-82 years) consecutive patients with a histologically proven diagnosis of colo-rectal adenocarcinoma or a highly suspected colo-rectal cancer on conventional colonoscopy underwent a four-slice CE CTC. The procedure was performed 70s (portal phase) after the intravenous bolus (3 ml/s) administration of 120 ml iodinated non-ionic contrast agent (370 mg iodine/ml). Scans were performed using the following parameters: 2.5mm beam collimation, pitch 1.25, 120 kV, 200 mAs, rotation time 0.75 s. Images were reconstructed with an effective thickness of 3.2mm at intervals of 1.6mm. Two radiologists independently evaluated the depth of tumour invasion into the colo-rectal wall (T), regional lymph node involvement (N), and extracolonic metastases (M). Disagreement was resolved by means of a consensus decision. The pathological results served as the standard of reference. Assessment was made of sensitivity, specificity and accuracy, as well as positive and negative predictive values were assessed.

RESULTS

CE CTC correctly staged the pT of 52/56 (93%) and the N of 40/56 (71%) lesions, as well as properly identifying 13/14 (93%) extracolonic findings.

CONCLUSION

The single portal venous phase CE CTC scanning protocol enables satisfactory preoperative assessment of T, N and M staging in patients with colo-rectal cancer.

Comparison of CT During Arterial Portography and MR During Arterial Portography in the Detection of Liver Metastases

OBJECTIVE

This study compared MR during arterial portography (MRAP) with CT during arterial portography (CTAP) with regard to the detection and differentiation of liver metastases before surgery.

MATERIALS AND METHODS

Fifteen patients with liver metastases were enrolled before surgery according to the guidelines of our institutional review board and good clinical practice. After mesentericography, unenhanced scans (Volume Zoom) were performed initially. For CTAP, the contrast medium was injected through the superior mesenteric artery. Images were acquired in portal and delayed enhancement. The MR protocol (1.5 T; Magnetom Symphony) started with T1-weighted fast low-angle shot (FLASH) T2-weighted turbo spin echo (TSE). MRAP followed with gadolinium-enhanced dynamic T1-weighted 3D FLASH. Delayed-phase T1-weighted 2D FLASH axial images were performed 2 min after IV injection of the contrast medium. Qualitative and quantitative evaluation of CTAP and MRAP was performed by three blinded radiologists regarding the number of lesions and their size, localization, and differential diagnosis.

RESULTS

The overall sensitivity in detecting liver metastases was 97% with MRAP and 93% with CTAP (p > 0.05, not significant [n.s.]). The specificity was calculated to be 97% for MRAP and 82% for CTAP (p < 0.0001, statistically significant [s.s.]). The differences in sensitivity were more accentuated if only lesions 10 mm or smaller were considered (95% vs 88%, p > 0.05, n.s.), for which the respective specificities were 95% and 80% (p < 0.0014, s.s.). Improvements in sensitivity and specificity were associated with a higher lesion-to-liver contrast-to-noise ratio (59.4 +/- 51.0 for MRAP vs 10.4 +/- 7.3 for CTAP) and resulted in higher diagnostic confidence in the differential diagnosis of liver lesions (p < 0.001, s.s.) and better interobserver agreement (median kappa value, 0.88 vs 0.63).

CONCLUSION

MRAP proved to be a reliable method in the preoperative detection of small liver metastases in particular, with a higher sensitivity and specificity than CTAP. If organizational difficulties of MRAP can be overcome, MRAP could be considered instead of CTAP in the preoperative invasive evaluation of metastatic liver disease.

New MR techniques for the detection of liver metastases

It is well established that hepatic resection improves the long-term prognosis of many patients with liver metastases. However, incomplete resection does not prolong survival, so knowledge of the exact extent of intra-hepatic disease is crucially important in determining patient management and outcome. MR imaging is well recognised as one of the most sensitive methods for detecting metastases. Recent developments in gradient coil design, the use of body phased array coils and the availability of novel MR contrast agents have resulted in MR being recognised as the pre-operative standard in this group of patients. However, diagnostic efficacy is extremely dependent on the choice and optimisation of pulse sequences and the appropriate use of MR contrast agents. This article reviews current MR imaging techniques for the detection and characterisation of metastases and discusses the relative capability of different techniques for detecting small lesions.

Diagnostic accuracy of portal-phase CT and MRI with mangafodipir trisodium in detecting liver metastases from colorectal carcinoma

AIM

To compare the diagnostic accuracy of single section spiral computed tomography (CT) and magnetic resonance imaging (MRI) with tissue-specific contrast agent mangafodipir trisodium (MnDPDP) in the detection of colorectal liver metastases.

MATERIAL AND METHODS

One hundred and twenty-five consecutive patients undergoing surgery for primary and/or metastatic disease were evaluated using CT (5 mm collimation and reconstruction interval, pitch 2), two-dimensional fast spoiled gradient echo (2D FSPGR) T1 and single shot fast-spin echo (SSFSE) T2 weighted breath-hold MRI sequences, performed before and after intravenous administration of MnDPDP. The reference standards were intraoperative ultrasound and histology.

RESULTS

The per-patient accuracy of CT was 72.8 versus 78.4% for unenhanced MRI (p = 0.071) and 82.4% for MnDPDP-enhanced MRI (p = 0.005). MnDPDP-enhanced MRI appeared to be more accurate than unenhanced MRI but this was not significant (p = 0.059). The sensitivity of CT was 48.4% versus 58.1% for unenhanced MRI (p = 0.083) and 66.1% for MnDPDP-enhanced MRI (p = 0.004). The difference in specificity between procedures was not significant. The per-lesion sensitivity was 71.7, 74.9 and 82.7% for CT, unenhanced MRI, and MnDPDP-enhanced MRI, respectively; the positive predictive value of the procedures was respectively 84.0, 96.0 and 95.8%. MnDPDP-enhanced MRI provided a high level diagnostic confidence in 92.5% of the cases versus 82.5% for both unenhanced MRI and CT. The kappa value for inter-observer variability was >0.75 for all procedures.

CONCLUSIONS

The diagnostic accuracy and sensitivity of MnDPDP-enhanced MRI is significantly higher than single section spiral CT in the detection of colorectal cancer liver metastases; no significant difference in diagnostic accuracy was observed between unenhanced MRI and MnDPDP-enhanced MRI.

Focal liver lesions: SPIO-, gadolinium-, and ferucarbotran-enhanced dynamic T1-weighted and delayed T2-weighted MR imaging in rabbits

PURPOSE

To compare a superparamagnetic iron oxide (SPIO), VSOP-C184, with a gadopentetate dimeglumine with regard to signal-enhancing effects on T1-weighted dynamic magnetic resonance (MR) images and with another SPIO contrast medium with regard to signal-reducing effects on delayed T2-weighted MR images.

MATERIALS AND METHODS

All experiments were approved by the responsible Animal Care Committee. Twenty rabbits (five for each contrast agent and dose) implanted with VX-2 carcinoma were imaged at 1.5 T. VSOP-C184 at 0.015 and 0.025 mmol Fe/kg was compared with gadopentetate dimeglumine at 0.15 mmol Gd/kg and ferucarbotran at 0.015 mmol Fe/kg. The imaging protocol comprised a T1-weighted dynamic gradient-echo (GRE) MR before injection and at 6-second intervals for up to 42 seconds after injection and a T2-weighted turbo spin-echo MR before and 5 minutes after injection. Images were evaluated quantitatively, and contrast media were compared by using nonparametric analysis of variance.

RESULTS

At dynamic T1-weighted GRE MR imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median peak contrast-to-noise ratio (CNR) was 20.7 (25th percentile, 16.3; 75th percentile, 22.6), 24.2 (25th percentile, 19.3; 75th percentile, 28.5), 16.4 (25th percentile, 13.7; 75th percentile, 20.3), and 14.0 (25th percentile, 11.4; 75th percentile, 16.8), respectively. Both doses of VSOP-C184 yielded significantly higher CNR (P < .05) than the other two agents. At T2-weighted turbo spin-echo imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median CNR was 15.0 (25th percentile, 13.4; 75th percentile, 21.3), 15.7 (25th percentile, 14.5; 75th percentile, 19.8), 11.3 (25th percentile, 8.2; 75th percentile, 12.2), and 15.7 (25th percentile, 12.5; 75th percentile, 22.4), respectively. There was no significant difference between VSOP-C184 and ferucarbotran; both had a significantly higher CNR than did gadopentetate dimeglumine.

CONCLUSION

VSOP-C184 produces higher liver-to-tumor contrast at dynamic T1-weighted imaging than does gadopentetate dimeglumine; at delayed T2-weighted imaging, the contrast is comparable to that achieved with ferucarbotran.

[Surgical treatment of gastric, enteric pancreatic endocrine tumors. Part 2. treatment of hepatic metastases]

The development of hepatic metastases (HM) marks a turning point in the evolutionand prognosis of well-differentiated endocrine tumors (ET). Management is usually multicisciplinary (chemotherapy, arterial chemo-embolization, percutaneous ablation, somatostatin analogs, biotherapy, and surgery). A thorough pre-operative work-up is neecessary to exclude extrahepatic disease and to detect tiny HM's. Complete resection (RO) is the only curative treatment for well-differentiated ET with HM. The type of resection is specific to each case and may range from wedge resection of a metastasis to complex hepatectomy with simultaneous resection of the primary ET. Cytoreductive surgery may be indicated for palliation when medical therapy fails to control endocrine symptoms. Operative mortality is low (0-6%) and global survival is 60-70% afterafter R) resection of HM of well-differentiated ET's. After resection of HM involving only one hepatic lobe, 5 year survival is better than 90%. When HM are multiple, bilobar and synchronous, the prognosis is very poor--only 10% of such patients can have a complete resection and this often requires a long prologue of ancillary procedures (chemotherapy, chemoembolization, portal vein ligation, percutaneous ablation). Hepatic transplantation (HT) has only a limited rôle in the treatment of HM for ET; mortality is high when HT is associated with large and complex resections, i.e. pancreaticoduodenectomy. Although there is no consensus in the literature, HT should be limited to the most optimal cases (young, good general health, well-differentiated tumor, slow evolution, complete resection of the primary rumor, and unresectable liver metastases). Global survival for HT in patients with ET is 60% at 2 years, 47% at 5 years; tumor-free survival at 5 years is 24%. HT for HM has better survival results for ET's of intestinal origin (carcinoids) than for duodenopancreatic ET's.

[Modern imaging for liver metastases from colorectal tumors]

Cross-sectional imaging modalities such as ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and Positron emission tomography (PET)/CT have benefited from rapid technical advances in recent years. In patients with colorectal tumors, multislice CT is the standard technique for preoperative evaluation and follow-up. It is faster than single-slice helical CT and allows for excellent 3D imaging of liver anatomy and tumor volumetry. The most accurate technique for detecting and characterizing focal liver lesions is MRI using state-of-the-art scanners and liver-specific contrast agents and should be used for preoperative evaluation of all possible surgical candidates. Whole-body FDG-PET and PET/CT are most useful in the detection of extrahepatic disease and may alter clinical management in up to 20% of patients by detecting extrahepatic spread of disease.

Hepatic imaging: comparison of modalities

This article describes a number of aspects of liver imaging, including the main reasons for imaging of the liver; the current status and recent developments of ultrasound, CT, MR imaging, and PET; and the role of these imaging modalities in the assessment of hepatic abnormalities. Finally, a systematic review of the current relevant literature on studies that compare modalities is presented, and a strategy for the work-up of liver diseases is proposed.

Liver metastases in candidates for hepatic resection: comparison of helical CT and gadolinium- and SPIO-enhanced MR imaging

PURPOSE

To prospectively compare accuracy of dynamic contrast material-enhanced thin-section multi-detector row helical computed tomography (CT), high-spatial-resolution three-dimensional (3D) dynamic gadolinium-enhanced magnetic resonance (MR) imaging, and superparamagnetic iron oxide (SPIO)-enhanced MR imaging with optimized gradient-echo (GRE) sequence for depiction of hepatic lesions; surgery and histologic analysis were the reference standard.

MATERIALS AND METHODS

Local ethics committee approval was granted, and written informed consent was obtained. Fifty-eight patients (45 men, 13 women; age range, 47-82 years) with hepatic metastases were imaged with multi-detector row CT (3.2-mm section thickness), 3D dynamic gadolinium-enhanced MR imaging (2.5-mm effective section thickness), and SPIO-enhanced MR by using an optimized T2-weighted GRE sequence. Images were reviewed independently by two blinded observers who identified and localized lesions with a four-point confidence scale. Accuracy of each technique was measured with alternative free-response receiver operating characteristic analysis. Results were correlated with findings at surgery with intraoperative ultrasonography or histopathologic examination. Statistical differences among techniques for each observer were measured.

RESULTS

Accuracy values for each observer for all metastases (n = 215) and 1.0-cm or smaller metastases (n = 80), respectively, follow: For CT, those for reader 1 were 0.82 and 0.65; for reader 2, 0.81 and 0.68. For gadolinium-enhanced MR imaging, those for reader 1 were 0.92 and 0.79; for reader 2, 0.90 and 0.76. For SPIO-enhanced MR imaging, those for reader 1 were 0.92 and 0.83; for reader 2, 0.92 and 0.81. For all metastases for both observers, there was no significant difference between MR techniques, but both were significantly more accurate than CT (P < .01). For metastases 1.0 cm or smaller and one observer, there was no significant difference between MR techniques, but both were more accurate than CT (P < .01); for the other observer, SPIO-enhanced MR imaging was more accurate than gadolinium-enhanced MR imaging (P < .05) and CT (P < .02), but there was no significant difference between gadolinium-enhanced MR imaging and CT (P = .2).

CONCLUSION

Accuracy for gadolinium-enhanced MR imaging and SPIO-enhanced MR imaging was similar. Both techniques were significantly more accurate than CT.

Colorectal liver metastases: CT, MR imaging, and PET for diagnosis--meta-analysis

PURPOSE

To perform a meta-analysis to obtain sensitivity estimates of computed tomography (CT), magnetic resonance (MR) imaging, and fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) for detection of colorectal liver metastases on per-patient and per-lesion bases.

MATERIALS AND METHODS

MEDLINE, EMBASE, Web of Science, and CANCERLIT databases and Cochrane Database of Systematic Reviews were searched for relevant original articles published from January 1990 to December 2003. Criteria for inclusion of articles were as follows: Articles were reported in the English, German, or French language; CT, MR imaging, or FDG PET was performed to identify and characterize colorectal liver metastases; histopathologic analysis (surgery, biopsy, or autopsy), intraoperative observation (manual palpatation, intraoperative ultrasonography [US]), and/or follow-up US was the reference standard; and data were sufficient for calculation of true-positive or false-negative values. A random-effects linear regression model was used to obtain sensitivity estimates in assessment of liver metastases.

RESULTS

Of 165 identified relevant articles, 61 fulfilled all inclusion criteria. Sensitivity estimates on a per-patient basis for nonhelical CT, helical CT, 1.5-T MR imaging, and FDG PET were 60.2%, 64.7%, 75.8%, and 94.6%, respectively; FDG PET was the most accurate modality. On a per-lesion basis, sensitivity estimates for nonhelical CT, helical CT, 1.0-T MR imaging, 1.5-T MR imaging, and FDG PET were 52.3%, 63.8%, 66.1%, 64.4%, and 75.9%, respectively; nonhelical CT had lowest sensitivity. Estimates of gadolinium-enhanced MR imaging and superparamagnetic iron oxide (SPIO)-enhanced MR imaging were significantly better, compared with nonenhanced MR imaging (P = .019 and P < .001, respectively) and with helical CT with 45 g of iodine or less (P = .02 and P < .001, respectively). For lesions of 1 cm or larger, SPIO-enhanced MR imaging was the most accurate modality (P < .001).

CONCLUSION

FDG PET had significantly higher sensitivity on a per-patient basis, compared with that of the other modalities, but not on a per-lesion basis. Sensitivity estimates for MR imaging with contrast agent were significantly superior to those for helical CT with 45 g of iodine or less.

Liver masses

In summary, MR imaging is superior to other imaging modalities, including CT, for the work-up of liver masses. The current challenge is whether the superior performance of MR imaging translates into a beneficial effect on patient management, disease outcome, and health care costs. New MR sequences, phased-array surface coils, and tissue-specific MR contrast agents suggest that MR imaging may exceed further the diagnostic ability of CT.

Preoperative assessment of focal liver lesions: multidetector computed tomography challenges magnetic resonance imaging

PURPOSE

To investigate prospectively multidetector computed tomography (CT) (MDCT) and magnetic resonance (MR) imaging (MRI) in the preoperative assessment of focal liver lesions.

MATERIAL AND METHODS

Multiphasic MDCT and conventional gadolinium-enhanced MRI were performed on 31 consecutive patients prior to hepatic surgery. All images were blindly analyzed as consensus reading. Lesion counts and their relation to vascular structures and possible extrahepatic disease were determined. The data from the MDCT and MRI were compared with the results obtained by intraoperative ultrasound (IOUS) and palpation. Histopathologic verification was available.

RESULTS

At surgery, IOUS and palpation revealed 45 solid liver lesions. From these, preoperative MDCT detected 43 (96%) and MRI 35 (78%) deposits. MDCT performed statistically better than MRI in lesion detection (P=0.008). Assessment of lesion vascular proximity was correctly determined by MDCT in 98% of patients and by MRI in 87%. Statistical difference was found (P=0.002). IOUS and palpation changed the preoperative surgical plan as a result of extrahepatic disease in 8/31 (26%) cases. In MDCT as well in MRI extrahepatic involvement was suspected in two cases.

CONCLUSION

MDCT was superior to MRI and nearly equal to IOUS in liver lesion detection and in the determination of lesion vascular proximity. However, both techniques fail to reliably detect extrahepatic disease.

Imaging the liver

Imaging of the liver is undertaken for the detection and characterization of suspected primary or secondary neoplasms, prior to planning a surgery or chemotherapy pump placement, for assessing treatment response, for evaluating biliary pathology, and for screening for liver neoplasms in high-risk groups. In this article, we review the advantages and disadvantages of various imaging modalities in the evaluation of the liver and formulate guidelines for the imaging of common clinical indications. A brief review of imaging findings in focal and diffuse liver disease is also presented.

Prospective study of contrast-enhanced computed tomography, computed tomography during arterioportography, and magnetic resonance imaging for staging colorectal liver metastases for liver resection

BACKGROUND

This study compared the value of contrast-enhanced helical computed tomography (CT), CT during arterioportography (CTAP), and contrast-enhanced magnetic resonance imaging (MRI) for staging patients with colorectal liver metastases.

METHODS

One hundred and twenty patients with known or suspected colorectal liver metastases were evaluated prospectively. MRI and CTAP were performed within 3 weeks of CT in patients with potentially resectable tumours. Results of imaging were compared with findings at surgery, intraoperative ultrasonography and histological examination.

RESULTS

Twenty patients were not considered for liver resection following CT. The remaining 100 patients underwent CT and CTAP, 85 of whom had CT, CTAP and MRI. The sensitivity and specificity were 73.0 and 96.5 per cent for CT, 87.1 and 89.3 per cent for CTAP, and 81.9 and 93.2 per cent for MRI. Positive predictive values were 89.7, 87.5 and 87.5 per cent respectively. Receiver-operator characteristic analysis gave an accuracy on a segment-by-segment analysis of 0.73 for CT, 0.87 for CTAP and 0.82 for MRI. Combining information from CT and CTAP, CT and MRI, or all three modalities, did not significantly increase the percentage of patients staged correctly (71, 72 and 76 per cent respectively).

CONCLUSION

The diagnostic accuracy of spiral CT, MRI and CTAP was similar. Combining modalities did not improve accuracy.

Modern hepatic imaging

This article provides a brief overview of the current status of commonly employed diagnostic techniques--US, CT, MR, and PET--for the evaluation of liver metastases and HCC as well as a description of imaging in RF ablation and liver transplantation. The various advantages and limitations of the techniques have been outlined. At the present time, at our center, MRI is used most often to evaluate these liver pathologies, due to its high accuracy for lesion detection and characterization.

Preoperative T and N staging of colorectal cancer: accuracy of contrast-enhanced multi-detector row CT colonography--initial experience

PURPOSE

To evaluate the accuracy of contrast material-enhanced multi-detector row computed tomographic (CT) colonography for preoperative staging of colorectal cancer.

MATERIALS AND METHODS

Forty-one patients with colorectal carcinoma underwent preoperative contrast-enhanced multi-detector row CT colonography. Images were obtained in the arterial (start delay of 35 seconds) and portal venous (start delay of 70 seconds) phases. The arterial phase was focused on the suspected region of neoplasm, whereas the venous phase included the whole abdomen and pelvis. Two radiologists independently evaluated the depth of tumor invasion into the colorectal wall (T) and regional lymph node involvement (N) on transverse CT images alone and in combination with multiplanar reformations (MPRs). Disagreements were resolved by means of consensus. CT findings were compared with pathologic results, which served as the reference standard. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were assessed. Differences in accuracy for T and N staging were assessed by using the McNemar test.

RESULTS

In T staging, overall accuracy was 73% when transverse images were evaluated alone and 83% when they were evaluated in combination with MPRs. This difference was not significant. N staging was associated with an overall accuracy of 59% with transverse images alone and 80% with combined transverse and MPR images (P <.01).

CONCLUSION

Contrast-enhanced multi-detector row CT colonography is an accurate technique for preoperative local staging of colorectal tumors.