Efficient method for calculating kinetic parameters using T1-weighted dynamic contrast-enhanced magnetic resonance imaging.

It has become increasingly important to quantitatively estimate tissue physiological parameters such as perfusion, capillary permeability, and the volume of extravascular-extracellular space (EES) using T(1)-weighted dynamic contrast-enhanced MRI (DCE-MRI). A linear equation was derived by integrating the differential equation describing the kinetic behavior of contrast agent (CA) in tissue, from which K(1) (rate constant for the transfer of CA from plasma to EES), k(2) (rate constant for the transfer from EES to plasma), and V(p) (plasma volume) can be easily obtained by the linear least-squares (LLSQ) method. The usefulness of this method was investigated by means of computer simulations, in comparison with the nonlinear least-squares (NLSQ) method. The new method calculated the above parameters faster than the NLSQ method by a factor of approximately 6, and estimated them more accurately than the NLSQ method at a signal-to-noise ratio (SNR) of < approximately 10. This method will be useful for generating functional images of K(1), k(2), and V(p) from DCE-MRI data.     

Algorithms for calculation of kinetic parameters from T1-weighted dynamic contrast-enhanced magnetic resonance imaging

PURPOSE: To quantify the errors involved in calculating dynamic parameters (K(trans) and ve) from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scans, and to develop alternative analyses to improve accuracy or increase processing speed. MATERIALS AND METHODS: This paper presents three different ways of handling the discrete samples of the arterial input and tissue response data with increasing fidelity, with which this continuous arterial input function (AIF) is represented. Also, a new noniterative approach to parameter estimation was developed from one used previously for analysis of radioactive tracer concentrations in radioangiography. The analysis methods were tested using simulated data. RESULTS: The more sophisticated schemes for data processing give more accurate parameter estimates when data are sparsely sampled, at least for the AIF that we modeled. The noniterative algorithm is very rapid in execution, but was more susceptible to measurement errors. CONCLUSION: The improved algorithms presented should be useful when the AIF and tissue response are sparsely sampled. The noniterative approach may be suitable for semiquantitative visualization, or where the AIF and tissue response are sampled accurately and with a small time interval between samples.     

Hyperintense nodules on non-enhanced T1-weighted gradient-echo magnetic resonance imaging of cirrhotic liver: fate and clinical implications

PURPOSE: To investigate the fate of hyperintense hepatic nodules on nonenhanced T1-weighted (T1w) gradient-echo (GRE) magnetic resonance (MR) images in cirrhotic patients. MATERIALS AND METHODS: A total of 79 cirrhotic patients with hyperintense nodules (>5 mm) on precontrast opposed-phase (repetition time (TR)/echo time (TE) = 140/2.7 msec) GRE images from initial MRI without T2-weighted (T2w) hyperintensity or arterial hypervascularity were subjected to analysis of subsequent MR images obtained at intervals of 12-56 months (mean = 24.5 months). Multiplicity of hyperintense nodules (group A, up to 8; group B, >8) was correlated with follow-up changes. RESULTS: Group B patients were younger (P = 0.003) than group A patients (mean = 47.5 and 56.2 years, respectively). In 66 group A patients, 39 out of 143 lesions (27%) were enlarged, including 20 malignantly transformed or borderline lesions. Of the 104 lesions (the eight largest lesions in each patient) in 13 group B patients, only three (2.9%) were enlarged. The results of best- and worst-case analyses showed that overall the lesions were benign in 91% and 82% of patients, respectively. CONCLUSION: T1w hyperintense nodules without T2w hyperintensity or arterial hypervascularity in the cirrhotic liver are benign in most cases. In younger patients with numerous macronodules, almost all of these lesions follow a benign course.     

扩散加权成像联合钆塞酸二钠增强MRI在肝转移瘤诊断中的研究进展

早期检出肝脏转移瘤对选择合适的治疗方案和提高病人术后生存率有较大价值。扩散加权成像主要反映活体组织中水分子的布朗运动,在肝脏局灶性病变的检出和定性方面显示出较大优势,尤其是在肝脏微小转移瘤的检出方面;而钆塞酸二钠(Gd-EOB-DTPA)增强MRI是一种既能进行肝脏动态增强扫描又能提供肝脏特异性信息的影像检查方法,在肝脏转移瘤检出方面的价值和准确性均较高。就DWI联合Gd-EOB-DTPA增强MRI在肝脏转移瘤检出中的研究进展予以综述。     

Planning transarterial radioembolization of colorectal liver metastases with Yttrium 90 microspheres: evaluation of a sequential diagnostic approach using radiologic and nuclear medicine imaging techniques

The purpose of the study was to establish a diagnostic approach to the preparation of patients with colorectal liver metastases considered for transarterial radioembolization (RE). Twenty-two patients sequentially underwent computed tomography (CT; thorax/abdomen), magnetic resonance imaging (MRI; liver; hepatocyte-specific contrast), positron emission tomography (PET/PET-CT; F18-fluoro-desoxy-glucose), and angiography with perfusion scintigraphy [planar imaging; tomography with integrated CT (SPECT-CT)]. The algorithm was continued when no contraindication or alternative treatment option was found. The impact of each test on the therapy decision and RE management was recorded. Patient evaluation using CT revealed contraindications for RE in 4/22 patients (18%). Of the remaining 18 patients, 2 were excluded and 3 were assigned to locally ablative treatment based on MRI and PET results (28%). The remaining 13 patients entered the planning algorithm: SPECT-CT revealed gastrointestinal tracer accumulations in 4 (31%) patients [SPECT, 2 (15%)], making a modified application necessary. In five patients (38%), planar scintigraphy revealed relevant hepatopulmonary shunting. Therapy was finally administered to all 13 patients without therapy-related pulmonary or gastrointestinal morbidity. Each part of the diagnostic algorithm showed a relevant impact on patient management. The sequential approach appears to be suitable and keeps the number of unnecessary treatments and therapy risks to a minimum.     

Comparison of gadoxetic acid-enhanced dynamic imaging and diffusion-weighted imaging for the preoperative evaluation of colorectal liver metastases

Purpose:

To retrospectively compare the diagnostic accuracy for the detection of colorectal liver metastases between gadoxetic acid‐enhanced MRI (EOB‐MRI) and diffusion‐weighted imaging (DWI) on 3.0 Tesla (T) system, and then to determine whether a combination of the two techniques may improve the diagnostic performance.

Materials and Methods:

Forty‐seven patients underwent MR imaging at 3.0T, including DWI (DWI set) and dynamic and hepatobiliary phase EOB‐MRI (EOB set) for the preoperative evaluation of colorectal liver metastases. All suspicious metastases were confirmed by hepatic surgery. Two blinded readers independently reviewed three different image sets, which consisted of DWI set, EOB set, and combined set. The accuracy was assessed by the area (Az) under the alternative‐free response receiver operating characteristic curve, and the sensitivity and positive predictive value (PPV) were calculated.

Results:

We found a total of 78 confirmed colorectal liver metastases in 42 of 47 patients. Each reader noted higher diagnostic accuracy of combined set of EOB‐MRI and DWI than DWI set and EOB set, without statistical significance. Regardless of the size of colorectal liver metastasis, each reader detected significantly more metastases on combined set than on DWI set, and PPV was significantly higher with DWI set than with EOB set or with combined set for one reader.

Conclusion:

EOB‐MRI was more useful for the detection of colorectal liver metastases, while DWI was more useful for their characterization. The combination of EOB‐MRI and DWI showed significantly higher accuracy and sensitivity for the preoperative detection of small colorectal liver metastases than DWI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Small colorectal liver metastases: Detection with SPIO-enhanced MRI in comparison with gadobenate dimeglumine-enhanced MRI and CT imaging

The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1 cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs seperately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1 cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.     

Glioma assessment using quantitative blood volume maps generated by T1-weighted dynamic contrast-enhanced magnetic resonance imaging: a receiver operating characteristic study

Purpose: To investigate the use of blood volume maps in the non-invasive separation of glioma grades.

Material and Methods: T1-weighted quantitative dynamic contrast-enhanced magnetic resonance imaging was used to quantify the fractional intratumoral blood volume of 41 gliomas (World Health Organization (WHO) grades II-IV). Two methods, mean fractional intratumoral blood volume determination and a system based on thresholds for extracting the tumor pixels with the highest vascularization from the blood volume maps, were investigated by means of receiver operating characteristic (ROC) analysis. The thresholds were adjusted using the ROC curve area calculated using the trapezoid method.

Results: The ability to separate grade II (WHO) gliomas from grades III-IV was nearly the same for both methods (ROC curve area 0.941 (threshold) versus 0.932 (mean value)) and significantly greater than the ability to separate grade IV (WHO) gliomas from grades II-III (ROC curve area 0.792 (threshold) versus 0.787 (mean value)). The best correspondence with WHO glioma grading was achieved using thresholds corresponding to only the 5.2% of tumor voxels with the largest blood volume for separating grade II gliomas and 4% for separating grade IV gliomas.

Conclusion: Use of the optimized threshold resulted in matching with the WHO grading system in 74% of cases.     

Solitary hepatic metastasis: Comparison of dynamic contrast-enhanced CT and MR imaging with fat-suppressed T2-weighted,Breath-hold T1-weighted FLASH,and dynamic gadolinium-enhanced FLASH sequences

Twenty consecutive cancer patients with a solitary hepatic metastasis detected with dynamic contrast-material—enhanced computed tomography (CT) who were considered for hepatic resection underwent magnetic resonance (MR) imaging within 18 days after CT. Histologic confirmation was obtained in all lesions. CT depicted 20 solitary lesions. MR imaging showed a solitary lesion in 14 patients, two lesions in three patients, and more than two lesions in three patients, for a total of 37 lesions. Twenty-three lesions less than 2 cm in diameter were missed with CT, and six lesions less than 1.3 cm in diameter were missed with MR imaging. MR imaging was superior to CT in the detection of hepatic metastases on a patient-by-patient basis (P <.01). The results suggest that MR imaging is superior to dynamic contrast-enhanced CT for the detection of hepatic metastases.     

Screening for liver metastases in women with mammary carcinoma: comparison of contrast-enhanced ultrasound and magnetic resonance imaging

Objective

The objective of the present study was to compare conventional B-mode ultrasound (BMU), contrast-enhanced ultrasound (CEUS), and magnetic resonance imaging (MRI) in the detection of liver metastases at the primary staging and follow-up of women with histologically confirmed mammary carcinoma.

Patients and methods

Included in the study were 55 women (aged 57.5±11.0 years, range 27-75 years; mean disease duration 57.5 months, range 5-168 months); of these, 17 women were examined as part of primary staging (staging group) and 38 women at follow-up (follow-up group). All patients underwent BMU (Philips HDI 5000), CEUS (Philips HDI 5000; 4.8 ml SonoVue), and MRI (Siemens Avanto 1.5 T) of the liver.

Results

In the staging group (n=17), a mass was detected by BMU in 24% (n=4), by CEUS in 29% (n=5), and by MRI in 47% (n=8); masses suspicious for malignancy were identified in 6% of patients with BMU and in 12% each by CEUS and MRI. Malignancy was not confirmed in any case by cytology or surgery. In the follow-up group (n=38), masses were identified by MRI in 53% of patients with suspicion of malignancy in 18%. Malignancy was confirmed in 16% of cases identified at MRI, in 13% of cases identified with CEUS, and in 11% of cases identified with BMU. The Pearson coefficients of correlation were r=.29 (P=.03) for MRI vs. BMU; r=.42 (P=.002) for MRI vs. CEUS; and r=.75 (P≤.001) for BMU vs. CEUS. With respect to malignancy, the Pearson coefficients of correlation were r=.40 (P=.099) for BMU vs. MRI and r=.71 (P=.0009) for CEUS vs. MRI.

Conclusions

Beginning in tumor stage III, the use of CEUS and MRI is associated with a significantly greater benefit in the detection of malignant tumors of the liver compared with conventional BMU. BMU appears to be adequate for primary staging and the follow-up of lower tumor stages.     

Comparison of Gadolinium-BOPTA and Ferucarbotran-enhanced three-dimensional T1-weighted dynamic liver magnetic resonance imaging in the same patient

OBJECTIVES: We sought to compare signal changes using Ferucarbotran and gadobenate dimeglumine (Gd-BOPTA) in dynamic 3D T1-weighted (T1w) GRE imaging of the liver. MATERIAL AND METHODS: Thirty patients were prospectively included in the study. All patients underwent 2 high-field magnetic resonance (MR) examinations: first with Gd-BOPTA (Gd) and then after a mean interval of 4 days with ferucarbotran (Feru). Dynamic MRI was obtained with a 3D T1w GRE sequence (TR 6.33, TE 2.31, flip angle 20 degrees ). Contrast enhanced scans were assessed before intravenous injection of the contrast agent (precontrast), and postcontrast during the arterial phase (30 seconds), portal venous phase (60 seconds), and equilibrium phase (120 seconds). The signal intensities (SIs) of liver, spleen, aorta, and portal vein were defined by region of interest measurements. Signal intensity changes (SICs) and percentage signal intensity change (PSIC) were calculated using the formulas SIC=(SI pre - SI post)/SI pre and PSIC=SIC x 100%. RESULTS: Positive signal enhancement was observed after intravenous injection of Feru during all dynamic measurements, whereas the mean SI values were lower compared with Gd. During the portal venous phase the mean SI of Gd was up to a factor of 2.1 higher (portal vein). The widest difference of SIC was observed during the equilibrium phase for liver parenchyma (Gd, 1.03; Feru, 0.24). The dynamic signal courses were similar for liver, portal vein and aorta. Different signal courses were obtained for the spleen. CONCLUSIONS: Feru-enhanced T1w dynamic images demonstrated significant signal increases for liver, vessels, and spleen but overall lower signal intensities than Gd-BOPTA. The dynamic signal courses of ferucarbotran were similar to that of Gd-BOPTA during ll perfusion phases except in the spleen. Thus, it may be possible to detect typical enhancement pattern of focal liver lesions with Feru-enhanced dynamic T1w MRI.     

Preoperative detection of hepatic metastases: Comparison of diffusion-weighted, T2-weighted fast spin echo and gadolinium-enhanced MR imaging using surgical and histopathologic findings as standard of reference

Purpose

The purpose of this study was to retrospectively compare the respective sensitivities of diffusion-weighted (DW), T2-weighted fast spin-echo (T2WFSE) and gadolinium chelate-enhanced MR imaging in the preoperative detection of hepatic metastases using intraoperative ultrasonographic and histopathologic findings as the standard of reference.

Materials and methods

Twenty-seven patients with 64 surgically and histopathologically proven hepatic metastases had MR imaging of the liver, including DW, T2WFSE and dynamic gadolinium chelate-enhanced MR imaging. Images from each MR sequence were separately analyzed by two readers with disagreements resolved by consensus readings. The findings on MR images were compared with intraoperative ultrasonographic and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each MR sequence. Statistical review of the lesion-by-lesion analysis was performed with the McNemar test.

Results

DW, T2WFSE and gadolinium chelate-enhanced MR imaging allowed the depiction of 54/64 (84.4%; 95% CI: 73.1-92.2%), 44/64 (68.8%; 95% CI: 55.9-79.8%), and 51/64 (79.7%; 95% CI: 67.8-88.7%) hepatic metastases respectively. DW MR images allowed depiction of significantly more hepatic metastases than did T2WFSE and was equivalent to gadolinium chelate-enhanced MR imaging (P = .002 and P = .375, respectively).

Conclusion

DW MR imaging is superior to T2WFSE imaging and equivalent to gadolinium chelate-enhanced MR imaging for the preoperative detection of hepatic metastases. Further studies however are needed to determine at what extent DW MR imaging can be used as an alternative to gadolinium chelate-enhanced MR imaging for the preoperative depiction of hepatic metastases.     

3T diffusion-weighted MRI in the response assessment of colorectal liver metastases after chemotherapy: Correlation between ADC value and histological tumour regression grading

PurposeThe purpose of the study was to correlate the apparent diffusion coefficient (ADC) values of diffusion-weighted MR imaging (DW-MRI) by 3T device with the histological tumour regression grading (TRG) analysis of colorectal liver metastases after preoperative chemotherapy.Materials and methodsOur study included thirty-five patients with colorectal liver metastases who had undergone MRI by 3T device (GE DISCOVERY MR750; GE Healthcare) after preoperative chemotherapy. DW-MRI was performed using a single-shot spin-echo echo-planar sequence with multiple b-values (0, 150, 500, 1000, 1500 s/mm²), thus obtaining an ADC map. For each liver lesion (more than 1 cm in diameter) the fitted ADC values were calculated by two radiologists in conference and three ROIs were drawn: around the entire tumour (ADC_e), at the tumour periphery (ADC_p) and at the tumour center (ADC_c). All ADC values were correlated with histopathological findings after surgery. Hepatic metastases were pathologically classified into five groups on the basis of TRG. Statistical analysis was performed on a per-lesion basis utilizing the one-way analysis of variance (ANOVA). This retrospective study was approved by our institutional review board; written informed consent was obtained from all patients.ResultsA total of 106 colorectal liver metastases were included for image analysis. TRG1, TRG2, TRG3, TRG4 and TRG5 were observed in 4, 14, 36, 35 and 17 lesions, respectively. ADC_e and ADC_p values were significantly higher in lesions classified as TRG1 (2.40 ± 0.12 × 10⁻⁹ m²/s and 2.28 ± 0.26 × 10⁻⁹ m²/s, respectively) and as TRG2 (1.40 ± 0.31 × 10⁻⁹ m²/s and 1.44 ± 0.35 × 10⁻⁹ m²/s), compared to TRG3 (1.16 ± 0.13 × 10⁻⁹ m²/s and 1.01 ± 0.18 × 10⁻⁹ m²/s), TRG4 (1.10 ± 0.26 × 10⁻⁹ m²/s and 0.97 ± 0.24 × 10⁻⁹ m²/s), and TRG5 (0.93 ± 0.17 × 10⁻⁹ m²/s and 0.82 ± 0.28 × 10⁻⁹ m²/s). ADC_e, ADC_p and ADC_c values were significantly different in TRG classes (p < 0.0001). Statistical correlations were found between the ADC_e, ADC_p, ADC_c values and the TRG classes (Spearman correlation coefficient were −0.568, −0.542 and −0.554, respectively).ConclusionOur study showed a significant correlation between ADC values of 3T DW-MRI and histological TRG of colorectal liver metastases after preoperative chemotherapy.     

High-resolution T2-weighted abdominal magnetic resonance imaging using respiratory triggering: impact of butylscopolamine on image quality

Background: Respiratory triggering allows the acquisition of high-resolution magnetic resonance (MR) images of the upper abdomen. However, the depiction of organs close to the gastrointestinal tract can be considerably impaired by ghosting artifacts and blurring caused by bowel peristalsis.

Purpose: To evaluate the effect of gastrointestinal motion suppression by intramuscular butylscopolamine administration on the image quality of a respiratory-triggered T2-weighted turbo spin-echo (T2w TSE) sequence of the upper abdomen.

Material and Methods: Images of 46 patients were retrospectively analyzed. Twenty-four patients had received intramuscular injection of 40 mg butylscopolamine immediately before MR imaging. Fourteen of the 24 patients in the butylscopolamine group underwent repeat imaging after a mean of 29 min. Quantitative analysis of the ghosting artifacts was done by measuring signal intensities in regions of interest placed in air anterior to the patient. In addition, image quality was assessed qualitatively by two radiologists by consensus.

Results: Spasmolytic medication with butylscopolamine reduced ghosting artifacts and significantly improved image quality of the respiratory-triggered T2w TSE sequence. The most pronounced effect of butylscopolamine administration on image quality was found for the pancreas and the left hepatic lobe. The rate of examinations with excellent or good depiction of the pancreas and the left hepatic lobe in the group without premedication and in the butylscopolamine group was 55% vs. 96% (pancreatic head), 35% vs. 88% (pancreatic body), 43% vs. 96% (pancreatic tail), and 45% vs. 83% (left hepatic lobe), respectively. Regarding the duration of the effect of intramuscular butylscopolamine, repeat imaging after a mean of 29 min did not result in a significant deterioration of image quality.

Conclusion: Intramuscular butylscopolamine administration significantly improves image quality of respiratory-triggered T2-weighted abdominal MR imaging by persistent reduction of peristaltic artifacts. MR imaging of the liver and pancreas in particular benefits from the suppression of gastrointestinal peristalsis by butylscopolamine.     

Comparison of FDG-PET, PET/CT and MRI for follow-up of colorectal liver metastases treated with radiofrequency ablation: initial results

PURPOSE: Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA. METHODS AND MATERIALS: Sixteen patients showed 25 FDG-positive colorectal liver metastases in pre-interventional PET/CT. Post-interventional PET/CT was performed 24h after ablation and was repeated after 1, 3 and 6 months and then every 6 months. PET and PET/CT data were compared with MR data sets acquired within 14 days before or after these time points. Either histological proof by biopsy or resection, or a combination of contrast-enhanced CT at fixed time points and clinical data served as a reference. RESULTS: The 25 metastases showed a mean size of 20mm and were treated with 39 RFA sessions. Ten lesions which developed LTP received a second round of RFA; four lesions received three rounds of treatment. The mean follow-up time was 22 months. Seventy-two PET/CT and 57 MR examinations were performed for follow-up. The accuracy and sensitivity for tumor detection was 86% and 76% for PET alone, 91% and 83% for PET/CT and 92% and 75% for MRI, respectively. CONCLUSIONS: In comparison to PET alone, PET/CT was significantly better for detecting LTP after RFA. There were no significant differences between MRI and PET/CT. These preliminary results, however, need further verification.     

Detection and classification of focal liver lesions in patients with colorectal cancer: retrospective comparison of diffusion-weighted MR imaging and multi-slice CT

Objectives

To compare the diagnostic performance of diffusion-weighted MR imaging (DWI) with multi-slice CT (MS-CT) in the detection and classification of focal liver lesions in patients with colorectal cancer.

Methods

In a retrospective study 68 patients who underwent DWI at 1.5 T (b-values of 50, 300 and 600 s/mm²) and contrast-enhanced MS-CT were analysed by two radiologists blinded to the clinical results. Imaging results were correlated with intraoperative surgical and ultrasound findings (n = 24), imaging follow-up or PET (n = 44). Sensitivity of DWI and MS-CT in detection of focal liver lesions was compared on a per-lesion and a per-segment basis. Receiver operator-characteristic (ROC) curves to determine the diagnostic performance and the sensitivities of correctly identifying liver metastases on a segmental base were calculated.

Results

For lesion detection, DWI was significantly superior to MS-CT both on a per-lesion (difference in sensitivities for reader 1 and 2 22.65% and 19.06%, p < 0.0001) and a per-segment basis (16.86% and 11.76%, p < 0.0001). Especially lesions smaller than 10 mm were better detected with DWI compared to MS-CT (difference 41.10% and 29.45%, p < 0.0001). ROC-analysis showed superiority for lesions classification (p < 0.0001) of DWI (AUC: 0.949 and 0.951) as compared to MS-CT (AUC: 0.879 and 0.892, p < 0.0001 and p = 0.005). DWI was able to filter out metastatic segments with a higher sensitivity (88.2 and 86.5%) compared to MS-CT (68.0 and 67.4%, p < 0.0001 and p = 0.005, respectively).

Conclusion

Compared to MS-CT DWI is both more sensitive in the detection of liver lesions and more accurate in determining the extent of metastatic disease in patients with colorectal cancer and therefore might help to optimize therapeutic management in those patients.     

Incremental value of arterial and equilibrium phase compared to hepatic venous phase CT in the preoperative staging of colorectal liver metastases: An evaluation with different reference standards

Purpose

To evaluate the incremental value of arterial and equilibrium phase compared to hepatic venous phase multidetector row CT (MDCT) in the preoperative staging of colorectal liver metastases (CLM) and to determine the influence of the reference standard.

Materials and methods

Fifty-three consecutive CLM patients underwent 16 detector row CT in hepatic arterial, venous, and equilibrium phase before surgery between March 2003 and January 2007. Detected lesions were characterized by three independent radiologists. The reference standard consisted of intraoperative palpation and ultrasound of the liver, and histopathological examination of the resected specimen. Additionally, data of follow-up CT was added. Statistical analysis was performed on a per-lesion basis.

Results

According to the reference standard 251 lesions were present, of which 203 (81%) were malignant (mean size: 29.4 ± 22.5 mm), and 41 (16%) were benign (mean size: 8.3 ± 7.7 mm). Sensitivity rates for CLM were comparable between triphasic and hepatic venous phase CT (P > 0.05). Sensitivity for the detection of CLM lowered from 60-77% to 52-68% when follow-up CT was added to the reference standard.

Conclusion

Arterial and equilibrium phase CT have no incremental value compared to hepatic venous phase MDCT in the detection of CLM. Sensitivity rates are, however, influenced by the type of reference standard used.     

Orbital benign and malignant lymphoproliferative disorders: Differentiation using semi-quantitative and quantitative analysis of dynamic contrast-enhanced magnetic resonance imaging

ObjectivesTo assess the value of dynamic contrast-enhanced MR imaging (DCE-MRI) in differentiating benign from malignant orbital lymphoproliferative disorders (OLPDs).MethodsThirty-nine patients with orbital lymphoproliferative disorders (21 malignant and 18 benign) underwent DCE-MRI scan for pre-treatment evaluation from March 2013 to December 2015. Both semi-quantitative (TTP, AUC, Slope_max) and quantitative (K^trans, k_ep, v_e) parameters were calculated, and compared between two groups. Receiver operating characteristic (ROC) curve analyses were used to determine the diagnostic value of each significant parameter.ResultsMalignant OLPDs showed significantly higher k_ep, lower v_e, and lower AUC than benign OLPDs, while no significant differences were found on K^trans, TTP and Slope_max. ROC analyses indicated that v_e exhibited the best diagnostic performance in predicting malignant OLPDs (cutoff value, 0.211; area under the curve, 0.896; sensitivity, 76.2%; specificity, 94.9%), followed by k_ep (cutoff value, 0.853; area under the curve, 0.839; sensitivity, 85.7%; specificity, 89.9%).ConclusionDCE-MRI and specially its derived quantitative parameters of k_ep and v_e are promising metrics for differentiating malignant from benign OLPDs.