Liver perfusion in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI): comparison of enhancement in Gd-BT-DO3A and Gd-EOB-DTPA in normal liver parenchyma.

PURPOSE: Within-patient comparison of the enhancement patterns of normal liver parenchyma after gadobutrol and gadoxetate disodium, with emphasis on the start of hepatocytic uptake of gadoxetate disodium. MATERIALS AND METHODS: Twenty-one patients (12 female, 9 male) without chronic liver disease underwent 1.5-T contrast-enhanced MRI twice, once with an extracellular contrast agent (gadobutrol) and once with a hepatospecific agent (gadoxetate disodium), using a T1-weighted keyhole sequence. Fifteen whole-liver datasets were acquired up to 5 min for both contrast agents and two additional datasets, up to 20 min, for gadoxetate. Signal intensities (SI) of the parenchyma, aorta and portal vein were measured and analysed relative to pre-contrast parenchymal SI. RESULTS: After gadoxetate, in 29% of the patients the parenchymal SI decreased by ≥5% after the initial vascular-phase-induced peak, while in the other 71% the parenchymal SI remained stable or gradually increased until up to 20 min after the initial peak. The hepatocytic gadoxetate uptake started at a mean of 37.8 s (SD 14.7 s) and not later than 76 s after left ventricle enhancement. CONCLUSION: Parenchymal enhancement due to hepatocytic uptake of gadoxetate can start as early as in the late arterial phase. This may confound the assessment of lesion appearance as compared to extracellular contrast such as gadobutrol. KEY POINTS: Gadoxetate-enhanced liver MRI results in early enhancement of normal parenchyma in patients The start of the hepatobiliary phase coincides with the late arterial phase. This may confound the assessment of lesion appearance compared to extracellular contrast. Different parenchymal enhancement patterns after gadoxetate were found for normal parenchyma.

Model-based iterative reconstruction and adaptive statistical iterative reconstruction techniques in abdominal CT: comparison of image quality in the detection of colorectal liver metastases.

PURPOSE: To prospectively evaluate dose reduction and image quality characteristics of abdominal computed tomographic (CT) scans reconstructed with model-based iterative reconstruction (MBIR) compared with adaptive statistical iterative reconstruction (ASIR) in oncology patients with colorectal liver metastases. MATERIALS AND METHODS: The study complied with HIPAA guidelines and was approved by the ethics committee of the institutional review board. All patients gave written informed consent. Fifty-one patients with colorectal liver metastases underwent body CT (thorax and abdomen) with a 64-section multidetector unit. With a radiation dose reduction by 2.36 mGy compared to standard of care CT with ASIR 50% (radiation dose, 7.54 mGy), MBIR can provide diagnostically acceptable CT scans without compromising image quality. Two radiologists independently assessed randomized images in a blinded manner. Imaging sets were compared for lesion detection, lesion conspicuity, overall image quality, and signal-to-noise ratio with a paired sample t test. Inter- and intraobserver agreement was assessed with the Cohen κ. RESULTS: The mean volume CT dose index was 5.18 mGy ± 0.76, mean dose-length product 374 mGy · cm ± 63.47, mean effective diameter 29.38 cm ± 3.46, and mean size-specific dose estimate 6.52 mGy ± 0.73. In small liver lesions (<10 mm), detection and conspicuity were significantly higher with MBIR than with ASIR for both right (t = 3.245, P = .004 and t = 2.696, P = .013, respectively) and left (t = 2.390, P = .038 and t = 2.283, P = .046) liver lobes. Subjective image noise (t = 4.506, P < .001), artifacts (t = 3.479, P = .001), and diagnostic confidence (t = 2.643, P = .011) were significantly better with MBIR than with ASIR. CONCLUSION: MBIR performed better than ASIR 50% at providing diagnostically acceptable CT scans without compromising image quality and in the detection of colorectal liver metastases.

Digital tomosynthesis in the detection of urolithiasis: Diagnostic performance and dosimetry compared with digital radiography with MDCT as the reference standard.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of digital tomosynthesis in comparison with digital radiography in the detection of urinary stones with MDCT as the reference standard. SUBJECTS AND METHODS: Fifty consecutively enrolled patients (32 men, 18 women; mean age, 51.5 years; range, 19-83 years) referred for unenhanced MDCT of the abdomen with suspicion of urinary stones also underwent digital tomosynthesis and digital radiography (anteroposterior and bladder inlet views). Images from all examinations were randomly read by three blinded radiologists. The mean effective doses for digital tomosynthesis, digital radiography, and low- and high-dose MDCT were measured on a male phantom. Free-response receiver operating characteristics and receiver operating characteristics analyses were used to compare the diagnostic performance of digital radiography with that of digital tomosynthesis. RESULTS: Both types of analysis showed significantly better performance of tomosynthesis over digital radiography for all urinary stones (p < 0.05). No such improvement was found for ureteral stones. The gain in sensitivity with tomosynthesis was largest for stones between 2 and 5 mm in diameter. The mean effective dose was 0.5 mSv for digital radiography, 0.85 mSv for tomosynthesis, 2.5 mSv for low-dose MDCT, and 12.6 mSv for high-dose MDCT. CONCLUSION: Use of digital tomosynthesis of the abdomen results in improved detection of urinary stones in general over digital radiography with only a slight increase in effective dose. Use of tomosynthesis, however, was not associated with major improvement in the diagnosis of ureteral stones. The technique has potential as an alternative imaging technique in the detection and follow-up of urinary stones.

Comparison of MRI (including SS SE-EPI and SPIO-enhanced MRI) and FDG-PET/CT for the detection of colorectal liver metastases.

Fluoro-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI), including unenhanced single-shot spin-echo echo planar imaging (SS SE-EPI) and small paramagnetic iron oxide (SPIO) enhancement, were compared prospectively for detecting colorectal liver metastases. Twenty-four consecutive patients suspected for metastases underwent MRI and FDG-PET/CT. Fourteen patients (58%) had previously received chemotherapy, including seven patients whose chemotherapy was still continuing to within 1 month of the PET/CT study. The mean interval between PET/CT and MRI was 10.2+/-5.2 days. Histopathology (n=18) or follow-up imaging (n=6) were used as reference. Seventy-seven metastases were detected. In nine patients, MRI and PET/CT gave concordant results. Sensitivities for unenhanced SS SE-EPI, MRI without SS SE-EPI and FDG-PET/CT were, respectively, 100% (p=9 x 10(-10) vs PET, p=8 x 10(-3) vs MRI without SS SE-EPI), 90% (p=2 x 10(-7) vs PET) and 60%. PET/CT sensitivity dropped significantly with decreasing size, from 100% in lesions larger than 20 mm (identical to MRI), over 54% in lesions between 10 and 20 mm (p=3 x 10(5) versus unenhanced SS SE-EPI), to 32% in lesions under 10 mm (p=6 x 10(-5) versus unenhanced SS SE-EPI). Positive predictive value of PET was 100% (identical to MRI). MRI, particularly unenhanced SS SE-EPI, has good sensitivity and positive predictive value for detecting liver metastases from colorectal carcinoma. Its sensitivity is better than that of FDG-PET/CT, especially for small lesions.

MRI of the cranial nerves--more than meets the eye: technical considerations and advanced anatomy.

Magnetic resonance (MR) imaging is the method of choice to evaluate the cranial nerves. Although the skull base foramina can be seen on CT, the nerves themselves can only be visualized in detail on MR. To see the different segments of nerves I to XII, the right sequences must be used. Detailed clinical information is needed by the radiologist so that a tailored MR study can be performed. In this article, MR principles for imaging of the cranial nerves are discussed. The basic anatomy of the cranial nerves and the cranial nerve nuclei as well as their central connections are discussed and illustrated briefly. The emphasis is on less known or more advanced extra-axial anatomy, illustrated with high-resolution MR images.

A prospective clinical study using a dynamic contrast-enhanced CT-protocol for detection of colorectal liver metastases.

OBJECTIVE: To evaluate a dynamic contrast-enhanced CT-protocol and compare this method with standard of care monophasic portovenous CT for detection of colorectal liver metastases. MATERIALS AND METHODS: A dynamic contrast-enhanced CT protocol was developed to detect liver metastasis in patients suffering from colorectal cancer, in clinical practice. The study was approved by the Hospital Ethics Committee. Written informed consent was obtained from all patients. 135 patients were included in this prospective study. All patients were naive to treatment. A dynamic contrast-enhanced CT was performed, followed by routine monophasic portovenous CT of thorax-abdomen-pelvis. 42 of these patients presented with liver metastasis. The number and lesion conspicuity of detected liver metastasis on dynamic contrast-enhanced CT using perfusion maps, was compared to monophasic CT. RESULTS: 135 patients were included, of which 42 presented with metastases to the liver. Dynamic contrast-enhanced CT outperformed portovenous CT for detection as well as conspicuity of colorectal liver metastasis, at a relatively low dose increment. Wilcoxon Signed Rank test had a p-value of 0.016 and <0.001 respectively for detection and conspicuity of colorectal liver metastasis. CONCLUSION: Dynamic contrast-enhanced CT increases the detection of colorectal liver metastasis, especially for lesions smaller than 15 mm, when compared to monophasic portovenous CT. Dynamic contrast-enhanced CT also has the added advantage of improved lesion conspicuity, which can positively influence reader confidence and clinical workflow.

Steroid-resistant sarcoidosis: is antagonism of TNF-alpha the answer?

Steroid-resistant sarcoidosis has conventionally been treated with various drugs, including methotrexate, azathioprine, cyclophosphamide, cyclosporine, antimalarial drugs and thalidomide, with variable success. There is a compelling need for more efficient and safer alternatives to these agents. Several lines of evidence suggest a critical role of TNF-alpha (tumour necrosis factor-alpha) in the initiation and organization of sarcoid granulomas. Inhibition of TNF-alpha with monoclonal antibodies has therefore received attention as a potential treatment option in therapy-resistant sarcoidosis. A number of case reports and small case series describe successful treatment of refractory disease with infliximab. Preliminary evidence from an RCT (randomized controlled trial) with infliximab in pulmonary sarcoidosis suggests a modest improvement in functional and radiological parameters. In contrast, the results with etanercept have been disappointing, perhaps related to differences in the mechanism of TNF-alpha blockade. The experience with adalimumab in sarcoidosis is too limited to draw conclusions. An open-label study and an RCT evaluating the efficacy of adalimumab in sarcoidosis with pulmonary and cutaneous involvement respectively, have been initiated. Although TNF-alpha antagonists appear relatively safe, especially when compared with conventional agents, caution is warranted in view of the increased incidence of tuberculosis, which may be a particular diagnostic challenge in patients with sarcoidosis. Pending publication of the RCTs, the use of TNF-alpha blockade in sarcoidosis should remain in the realm of experimental treatment.

Intravoxel incoherent motion and dynamic contrast-enhanced MRI for differentiation between hepatocellular adenoma and focal nodular hyperplasia.

OBJECTIVE: To examine if intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced MRI (DCE-MRI) can be used as new and supplemental MRI techniques to differentiate hepatocellular adenomas (HCAs) from focal nodular hyperplasias (FNHs) and analyse if diffusion parameter apparent diffusion coefficient (ADC) and IVIM parameter true diffusion coefficient (D) differ in doing so. METHODS: This prospective study included 21 patients (8 HCAs and 13 FNHs) who underwent a specifically designed MRI scanning protocol, including series for analysis of IVIM (four b-values 0, 10, 150 and 800 s mm-2) and DCE-MRI. On a dedicated workstation, identical regions of interest were placed in parametric maps of Ktrans, Ve, D and ADC in each lesion for quantification. Diagnostic accuracy was assessed using receiver operating characteristics analysis. Time-intensity curves (TICs) were classified in different types. RESULTS: HCAs had significantly lower values for Ktrans (mean 1.45 vs 2.68 min-1; p = 0.029) and D (mean 1.02 × 10-3 vs 1.22 × 10-3 mm2 s-1; p = 0.033). Both parameters showed good diagnostic accuracy of 76%. TIC analysis could not differentiate between HCAs and FNHs. CONCLUSION: In this exploratory study, Ktrans and D were able to differentiate HCAs from FNHs in most cases, whereas Ve, ADC and TIC analysis were not. Advances in knowledge: Histological differences between HCAs and FNHs can be quantified on MRI using Ktrans and D.

Internal hernia after laparoscopic Roux-en-Y gastric bypass: a correlation between radiological and operative findings.

BACKGROUND: Even though internal hernia (IH) after a laparoscopic Roux-en-Y gastric bypass (LRYGB) is a well-known entity for bariatric surgeons and radiologists, accurate diagnosis remains difficult. The aim of this study was to evaluate the sensitivity and specificity of ten different CT findings in patients with a proven internal hernia after a LRYGB. METHODS: A retrospective analysis of all LRYGB patients who underwent an explorative laparoscopy for abdominal pain has been performed. Preoperative CT scans were individually reviewed by two radiologists specialized in abdominal CT imaging in a randomized blind way. These results were compared with the operative reports. RESULTS: Between 2004 and 2013, 7,328 patients underwent a LRYGB. One hundred sixty nine of these patients underwent an explorative laparoscopy for abdominal pain after a LRYGB, 131 of which had a preoperative CT scan. Of these 131 patients, 72 suffered from an IH. Fifty-nine patients had no IH and served as control group. Mesenteric swirl was the best predictor with for reader 1 a sensitivity of 68% and specificity of 86% and for reader 2 a sensitivity of 89% and specificity of 63%. Other signs had an even larger interobserver variability. CONCLUSIONS: A CT scan can help in confirming the diagnosis of an IH, especially if a mesenteric swirl is present. However, since the presented sensitivities are variable and do not reach 100%, IH might be missed, implicating that a high index of suspicion with a low threshold for explorative laparoscopy/-tomy remains the cornerstone of appropriate treatment.

Focal liver lesions detection: Comparison of respiratory-triggering, triggering and tracking navigator and tracking-only navigator in diffusion-weighted imaging.

PURPOSE: To compare low b value (10s/mm(2)) spin-echo echo-planar (SE-EP) diffusion-weighted imaging (DWI) acquired with respiratory-triggering (RT), triggering and tracking navigator (TT), tracking only navigator (TRON) techniques for image quality and focal liver lesions (FLL) detection in non-cirrhotic patients. MATERIAL AND METHODS: This bi-centric study was approved by the institutional review boards; informed consent was obtained. Eighty-three patients were prospectively included and SE-EP-DWI with RT, TT and TRON techniques were performed. DWI sequences were randomized and independently analyzed by two readers. The qualitative evaluation was based on a 3-point score for axial artifacts (motion, ghost, susceptibility artifacts and distortion) and stair-step artifacts. Sensitivity of FLL detection was calculated for all lesions together and after lesion size stratification (≤ 10 mm, >10-20mm and >20mm). The standard of reference consisted of a retrospective reading of the conventional MRI, the three DWI sequences and by follow-up (12 months): a total of 409 FLL were detected. Data between sequences was compared with non-parametric tests. Cohen's kappa coefficient was used for inter-observer agreement. RESULTS: Image quality was comparable for RT and TT. TRON showed statistically significantly more axial artifacts for the two readers (p<0.05). Stair-step artifacts were not statistically significantly different between DWI sequences. Overall sensitivities for RT, TT, TRON were 85%, 86%, 82% and 86%, 89% 83%, respectively, for readers 1 and 2. The inter-observer agreement was very good. CONCLUSION: Image quality was better for RT and TT compared to TRON. Overall sensitivities for FLL detection were comparable between techniques and readers.

An unusual cervical tumor as presentation of a non-hodgkin lymphoma.

Rare cervical cancers are responsible for a minority of cases encountered by a clinician. However, behavioral patterns, management, and prognosis of certain rare cervical cancers differ from either squamous carcinomas or adenocarcinomas. Here we present a case of a locally advanced cervical tumor as a presentation of an extranodal cervical non-Hodgkin lymphoma (NHL), with a review of the current literature.

Staging colorectal cancer with the TNM 7(th): the presumption of innocence when applying the M category.

One of the main changes of the current TNM-7 is the elimination of the category MX, since it has been a source of ambiguity and misinterpretation, especially by pathologists. Therefore the ultimate staging would be better performed by the patient's clinician who can classify the disease M0 (no distant metastasis) or M1 (presence of distant metastasis), having access to the completeness of data resulting from clinical examination, imaging workup and pathology report. However this important change doesn't take into account the diagnostic value and the challenge of small indeterminate visceral lesions encountered, in particular, during radiological staging of patients with colorectal cancer. In this article the diagnosis of these lesions with multiple imaging modalities, their frequency, significance and relevance to staging and disease management are described in a multidisciplinary way. In particular the interplay between clinical, radiological and pathological staging, which are usually conducted independently, is discussed. The integrated approach shows that there are both advantages and disadvantages to abandoning the MX category. To avoid ambiguity arising both by applying and interpreting MX category for stage assigning, its abandoning seems reasonable. The recognition of the importance of small lesion characterization raises the need for applying a separate category; therefore a proposal for their categorization is put forward. By using the proposed categorization the lack of consideration for indeterminate visceral lesions with the current staging system will be overcome, also optimizing tailored follow-up.

Prediction and monitoring of treatment effect using T1-weighted dynamic contrast-enhanced magnetic resonance imaging in colorectal liver metastases: potential of whole tumour ROI and selective ROI analysis.

PURPOSE: To evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for prediction and early monitoring of treatment in colorectal liver metastases. MATERIALS AND METHODS: Ten patients were included. Baseline and follow-up DCE-MRI examinations were evaluated by whole tumour and selected ROI placements calculating Kep-values. Selective ROIs, concentric-like and hot spot, were drawn on early arterial phase images. Monitoring of treatment was performed comparing RECIST1.1 criteria with whole tumour and selected ROI placement. To evaluate treatment effect between responders and non-responders, independent samples t-test was used on Kep-values. RESULTS: In each patient largest lesion was evaluated totalling 10 target lesions. At baseline, for whole tumour ROI placements mean Kep-values in responders were significantly higher than mean Kep-values in non-responders (t=7.481, p<0.001). Selective ROI placement comparison of mean Kep-values at baseline and after 6 weeks of treatment (first follow-up measurement) showed significant decrease in responding patients (t=4.706, p=0.003) whereas increase in Kep-values in non-responding patients was not statistically significant. CONCLUSION: This preliminary study shows that baseline Kep for whole tumour ROI is a predictor for treatment outcome. Decrease of Kep using selective ROIs allows early identification of response after 6 weeks of treatment.

Perfusion maps of the whole liver based on high temporal and spatial resolution contrast-enhanced MRI (4D THRIVE): feasibility and initial results in focal liver lesions.

PURPOSE: To prospectively evaluate a new imaging sequence (4D THRIVE) for whole liver perfusion in high temporal and spatial resolution. Feasibility of parametric mapping and its potential for characterizing focal liver lesions (FLLs) are investigated. MATERIALS AND METHODS: Fifteen patients suspected for colorectal liver metastases (LMs) were included. Parametric maps were evaluated qualitatively (ring-enhancement and lesion heterogeneity) and compared to three-phased contrast-enhanced MRI. Quantitative analysis was based on average perfusion values of entire FLLs. Reference standard comprised surgery with histopathology or follow-up imaging. Fisher's exact test was used for qualitative and Kruskal-Wallis test for quantitative analysis. RESULTS: In total 29 LMs, 17 hemangiomas and 4 focal nodular hyperplasias were evaluated. FLLs could be differentiated by qualitative assessment of parametric maps respectively three-phased contrast-enhanced MRI (Fisher's p<0.001 for comparisons between LMs and hemangiomas and LMs and FNHs for both ring-enhancement and lesion heterogeneity) rather than by quantitative analysis of parametric maps (Chi-square for Kep=0.33 (p=0.847) and Chi-square for Kel=1.35 (p=0.509)). CONCLUSION: This preliminary study shows potential of 4D THRIVE for whole liver imaging enabling calculation of parametric maps. Qualitative rather than quantitative analysis was accurate for differentiating malignant and benign FLLs.

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/mm(2)) 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.

Evaluation of true diffusion, perfusion factor, and apparent diffusion coefficient in non-necrotic liver metastases and uncomplicated liver hemangiomas using black-blood echo planar imaging.

PURPOSE: To assess the added value of true diffusion (D), perfusion factor (f) and apparent diffusion coefficient at low b-values (ADC(low)) for differentiation between liver metastases and hemangiomas based on respiratory-triggered high-resolution Black-Blood Single-Shot SpinEcho Echo Planar Imaging (BB SS SE-EPI). MATERIALS AND METHODS: Twenty-five patients suspected for malignant colorectal liver lesions were included in this study. A total of 106 lesions were examined. Different b-value images were compared for lesion conspicuity, image quality and artifacts using rank order statistic (RIDIT) and Student's t-test. D, f, and ADC(low) values were calculated. Pearson correlation coefficient is used for comparison of interobserver variability. RESULTS: Best lesion conspicuity (p<0.05) was achieved with BB SS SE-EPI (b=0 and 10s/mm(2)); best image quality (p<0.05) with b=10s/mm(2). Image artifacts were lowest (p<0.05) with b=0s/mm(2). Over the whole sample, D in metastases (D(met)) was significantly (p<0.05) lower than D in hemangiomas (D(hem)); f and ADC(low) of metastases (f(met), respectively, ADC(lowmet)) were significantly (p<0.05) higher than f and ADC(low) of hemangiomas (f(hem), respectively, ADC(lowhem)). All Pearson correlations were statistically significant at a 0.01 level. CONCLUSIONS: This preliminary study shows the potential of BB SS SE-EPI as a useful technique to aid in differentiating between liver metastasis and hemangioma. The calculation of D, f and ADC(low) provides useful additional information for differentiating metastases from hemangiomas.

Focal liver lesion detection and characterization: comparison of non-contrast enhanced and SPIO-enhanced diffusion-weighted single-shot spin echo echo planar and turbo spin echo T2-weighted imaging.

PURPOSE: To compare lesion conspicuity and image quality between single-shot spin echo echo planar imaging (SS SE-EPI) before, immediately and 5min after intravenous (IV) injection of superparamagnetic iron oxide (SPIO) for detecting and characterizing focal liver lesions (FLLs). MATERIALS AND METHODS: Twenty-five patients suspected for colorectal liver metastases were prospectively included. Lesion detection and characterization were compared between all SS SE-EPI and T2-weighted turbo spin echo (T2w TSE) sets (two-sided Fisher's exact test). Image quality and lesion conspicuity were compared for SS SE-EPI sets using rank order statistic (RIDIT). Reference standard comprised of surgery, biopsy and/or follow-up. RESULTS: Reference standard demonstrated 18 benign and 43 malignant FLLs. Best lesion detection (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI. Lesion characterization was best using all T2w TSE sequences. Best image quality and lesion conspicuity (p<0.05) was achieved with non-contrast-enhanced SS SE-EPI. CONCLUSION: Non-contrast-enhanced SS SE-EPI was best for lesion detection. SS SE-EPI sequences were not useful for lesion characterization (differentiation between benign and malignant lesions). Unenhanced SS SE-EPI did not allow differentiation especially as many benign FLLs were hyperintense on the highest b-value images. Combining unenhanced and SPIO-enhanced SS SE-EPI performed better but still was not clinically useful due to variable degree of uptake and vascular pooling of SPIO for (especially) benign FLLs. T2w TSE with SPIO-enhancement was needed for characterization.

Improved focal liver lesion detection: comparison of single-shot spin-echo echo-planar and superparamagnetic iron oxide (SPIO)-enhanced MRI.

PURPOSE: To prospectively compare single-shot spin-echo echo-planar imaging (SSSE-EPI) using b = 0, 10, 150, and 400 seconds/mm(2) with standard MRI techniques after intravenous super paramagnetic iron oxide (SPIO) in the detection and characterization of focal liver lesions with focus on small (<10 mm) focal liver lesions. MATERIALS AND METHODS: A total of 25 patients suspected for colorectal liver metastases were included. Number of detected lesions was evaluated. Image quality was compared between SSSE-EPI sequence and post-SPIO (fat-suppressed T1-weighted [T1w] gradient echo [GE], T2-weighted [T2w] turbo spin echo [TSE] and T2* GE) sequences using rank order statistic (RIDIT). Lesion characterization was performed for SSSE-EPI and for all remaining sequences pre- and post-SPIO. Reference standard comprised surgery, biopsy, and/or follow-up. RESULTS: Reference standard demonstrated 25 hemangiomas and 70 metastases. Best lesion detection respectively best image quality (P < 0.05) was achieved with SSSE-EPI (b = 10 seconds/mm(2)) post-SPIO T1w GE and T2w turbo spin echo. Lesion characterization using all sequences pre- and post-SPIO performed best for lesion characterization compared with SSSE-EPI. CONCLUSION: This preliminary study shows the potential of SSSE-EPI as a stand-alone sequence for the detection of liver hemangiomas and metastases when compared with SPIO-enhanced imaging. Sequences pre- and post-SPIO are needed for qualitative lesion characterization.