Intra-individual, randomised comparison of the MRI contrast agents gadobutrol versus gadoteridol in patients with primary and secondary brain tumours, evaluated in a blinded read

Objective

To prove that 1.0 M gadobutrol provides superior contrast enhancement and MRI image characteristics of primary and secondary brain tumours compared with 0.5 M gadoteridol, thereby providing superior diagnostic information.

Methods

Brain MRI was performed in two separate examinations in patients scheduled for neurosurgery. Independent injections of 1.0 M gadobutrol and 0.5 M gadoteridol at doses of 0.1 mmol Gd/kg body weight were administered per patient in randomised order. Evaluation was performed in an off-site blinded read.

Results

Fifty-one patients in the full analysis set (FAS) were eligible for efficacy analysis and 44 for the per-protocol analysis. For the primary efficacy variable “preference in contrast enhancement for one contrast agent or the other”, the rate of “gadobutrol preferred” was estimated at 0.73 (95 % confidence interval 0.61; 0.83), showing significant superiority of gadobutrol over gadoteridol. Calculated lesion-to-brain contrast and the results of all qualitative secondary efficacy variables were also in favour of gadobutrol. Keeping a sufficient time delay after contrast application proved to be essential to get optimal image quality.

Conclusion

Compared with 0.5 M gadoteridol, 1.0 M gadobutrol was proven to have significantly superior contrast enhancement characteristics in a routine MRI protocol of primary and secondary brain tumours.

Key Points

? Contrast-enhanced MRI is the imaging technique of choice in CNS tumours. ? Intra-individual comparison proved preference of gadobutrol over gadoteridol. ? Quantitative results also showed significant superiority regarding lesion-to-brain contrast. ? The time interval between contrast administration and image acquisition must be sufficient.     

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     

Intra-individual randomised comparison of gadobutrol 1.0?M versus gadobenate dimeglumine 0.5?M in patients scheduled for preoperative breast MRI

Objective

To demonstrate non-inferiority of gadobutrol versus gadobenate dimeglumine by intra-individually comparing 0.1?mmol/kg body weight doses for contrast-enhanced breast magnetic resonance imaging (MRI) and prospectively evaluating lesion detection and characterisation in a multicentre trial.

Methods

Two identical breast MRI examinations were performed in 72 patients with biopsy-proven breast cancer, separated by 1?C7?days. Gadobutrol 1.0?M or gadobenate 0.5?M were administered in a randomised order. Lesion detection and characterisation were performed by two independent blinded readers. Lesion tracking, which compared on-site readings and histology from surgery or biopsy, was performed by a third reader. Differences in lesion detection and characterisation were compared between the two contrast agents.

Results

Among 103 lesions, 96 were malignant and 7 were benign. No difference in lesion detection was identified between the contrast agents (82.33?% for gadobutrol, 81.60?% for gadobenate). Assessment of sensitivity in lesion characterisation and Breast Imaging Reporting and Data Systems showed no difference between gadobutrol (92.63?%) and gadobenate (90.53?%). Regarding morphology, there was more non-focal enhancement for gadobutrol than for gadobenate (P?=?0.0057).

Conclusion

Non-inferiority of gadobutrol compared with gadobenate was demonstrated for breast lesion detection and sensitivity in lesion characterisation in breast MRI.

Key Points

? Contrast-enhanced magnetic resonance imaging is now widely used for breast problems. ? Lesion detection in breast MRI differs according to the contrast agent. ? Thus we compared gadobutrol 1?M with gadobenate dimeglumine 0.5?M. ? Gadobutrol was non-inferior to gadobenate dimeglumine for detecting and characterising malignant lesions.     

Performance of gadofosveset-enhanced MRI for staging rectal cancer nodes: can the initial promising results be reproduced?

Objectives

A previous study showed promising results for gadofosveset-trisodium as a lymph node magnetic resonance imaging (MRI) contrast agent in rectal cancer. The aim of this study was to prospectively confirm the diagnostic performance of gadofosveset MRI for nodal (re)staging in rectal cancer in a second patient cohort.

Methods

Seventy-one rectal cancer patients were prospectively included, of whom 13 (group I) underwent a primary staging gadofosveset MRI (1.5-T) followed by surgery (± preoperative 5 × 5 Gy) and 58 (group II) underwent both primary staging and restaging gadofosveset MRI after a long course of chemoradiotherapy followed by surgery. Nodal status was scored as (y)cN0 or (y)cN+ by two independent readers (R1, R2) with different experience levels. Results were correlated with histology on a node-by-node basis.

Results

Sensitivity, specificity and area under the receiver operating characteristics curve (AUC) were 94 %, 79 % and 0.89 for the more experienced R1 and 50 %, 83 % and 0.74 for the non-experienced R2. R2’s performance improved considerably after a learning curve, to an AUC of 0.83. Misinterpretations mainly occurred in nodes located in the superior mesorectum, nodes located in between vessels and nodes containing micrometastases.

Conclusions

This prospective study confirms the good diagnostic performance of gadofosveset MRI for nodal (re)staging in rectal cancer.

Key Points

? Gadofosveset-enhanced MRI shows high performance for nodal (re)staging in rectal cancer. ? Gadofosveset MRI may facilitate better selection of patients for personalised treatment. ? Results can be reproduced by non-expert readers. ? Experience of 50–60 cases is required to achieve required expertise level. ? Main pitfalls are nodes located between vessels and nodes containing micrometastases.     

Value of gadofosveset-enhanced MRI and multiplanar reformatting for selecting good responders after chemoradiation for rectal cancer

Objectives

Our primary objective was to evaluate diagnostic performance of gadofosveset T1-weighted magnetic resonance imaging (T1W MRI) for discriminating between ypT0–2 and ypT3–4 tumours after chemoradiation therapy (CRT) for rectal cancer compared with T2W MRI for a general and expert reader. Second objectives included assessing the value of multiplanar reformatting (MPR) and interobserver agreement.

Methods

A general and expert reader evaluated 49 patients for likelihood of ypT0–2 tumour after CRT on T2W, gadofosveset T1W MRI, and gadofosveset T1W MRI + T2W MRI. The general reader scored with and without MPR. Confidence level scores were used to construct receiver-operating characteristic (ROC) curves. Area under the curve (AUC) values and diagnostic parameters were calculated and compared.

Results

Gadofosveset T1W MRI + T2W MRI showed slightly superior sensitivity than T2W MRI for the general but not the expert reader. Specificity was higher for the expert on gadofosveset T1W MRI only compared with T2W MRI only (100 % vs. 82 %). MPR did not increase diagnostic performance. Interobserver agreement was highest for the combination of gadofosveset-enhanced T1W imaging plus T2W MRI.

Conclusions

The sole use or addition of gadofosveset-enhanced T1W MRI to T2W MRI did not increase significantly diagnostic performance for assessing ypT0–2 tumours. Adding gadofosveset-enhanced T1W MRI slightly increased sensitivity for the general reader and specificity for the expert reader, but this increase was not significant for more accurate clinical decision making. MPR did not improve diagnostic performance.

Key Points

? ycT restaging with MRI in rectal cancer is challenging. ? Gadofosveset-enhanced T1W MRI has shown promise for nodal restaging. ? Gadofosveset-enhanced T1W MRI did not significantly increase diagnostic performance for assessing ypT0–2-tumours. ? Addition of the gadofosveset sequence to T2W MRI slightly increased sensitivity for the general reader. ? MPR did not improve diagnostic performance of ycT staging.     

Macrocyclic contrast agents for magnetic resonance imaging of chronic myocardial infarction: intraindividual comparison of gadobutrol and gadoterate meglumine

Objectives

To compare 0.15?mmol/kg gadobutrol for late gadolinium enhancement (LGE) imaging of chronic myocardial infarction with a relaxivity-adjusted dose of gadoterate meglumine (Gd-DOTA).

Methods

Seventeen patients with suspected chronic myocardial infarction underwent LGE imaging at 1.5 T, acquiring an inversion-recovery-prepared gradient echo sequence 15?min after contrast agent administration. Each patient underwent LGE imaging twice, once after administration of 0.15?mmol/kg gadobutrol (r1?=?5.2?l?mmol^-1?s^-1) and after 0.22?mmol/kg Gd-DOTA (r1?=?3.6?l?mmol^-1?s^-1). Two readers independently determined infarct size and contrast-to-noise ratios of infarcted myocardium to remote myocardium (CNR_remote) and to the left ventricular lumen (CNR_lumen).

Results

LGE was present in 14 patients. Infarct sizes determined after administration of gadobutrol [23.4?ml; 95?% CI (14.4; 32.5)] and Gd-DOTA [22.1?ml; 95?% CI (13.0; 31.1)] were not statistically different (P?=?0.22). The CNR_remote of LGE in infarcted myocardium on gadobutrol- and Gd-DOTA-enhanced images was 44.1 [95?% CI (31.0; 57.1)] and 45.2 [95?% CI (32.2; 58.3)], respectively (P?=?0.73). CNR_lumen was significantly higher on gadobutrol-enhanced LGE images [12.7; 95?% CI (2.5; 23.0) versus 6.8; 95?% CI (-3.5; 17.0); P?=?0.02].

Conclusion

At relaxivity-adjusted doses, gadobutrol and Gd-DOTA yielded similar infarct sizes with superior contrast between infarcted myocardium and left ventricular lumen on gadobutrol-enhanced images.

Key points

? Contrast-enhanced magnetic resonance imaging is increasingly used to assess the myocardium ? Macrocyclic Gd-based contrast agents are considered to be safer than linear agents ? Myocardial infarction MRI can be performed using either gadobutrol or gadoterate meglumine ? Contrast between infarcted myocardium and the left ventricular lumen was greater using gadobutrol ? The minimum macrocyclic dose needed for reliable LGE imaging requires further evaluation     

Immediate post-operative MRI suggestive of the site and timing of glioblastoma recurrence after gross total resection: a retrospective longitudinal preliminary study

Objectives

To retrospectively identify morphological and physiological post-operative magnetic resonance imaging (MRI) characteristics predictive of glioblastoma recurrences after gross total resection (gross-TR).

Methods

Resection margins of 24 glioblastoma were analysed immediately post-operatively (MRI?≤?2 h) and early post-operatively (24 h?≤?MRI?≤?48 h), and subdivided into areas with and without subtle contrast enhancement previously considered non-specific. On follow-up MRI, tumour regrowth areas were subdivided according to recurrence extent (focally/extended) and delay (≤6 and ≥12 months). Co-registration of pre-operative, immediately post-operative and early post-operative MRI with the first follow-up MRI demonstrating recurrence authorised their morphological (contrast enhancements) and physiological (rCBV) characterisation.

Results

Morphologically, on immediately post-operative MRI, micro-nodular and frayed enhancements correlate significantly with early recurrences (≤6 months). After gross-TR the absence of these enhancements is associated with a significant increase in progression-free survival (61 vs 15 weeks respectively) and overall survival (125 vs 51 weeks respectively). Physiologically, areas with a future focal recurrence have a trend toward higher rCBV than other areas.

Conclusion

Immediately post-operative topography of micro-nodular and frayed enhancements is suggestive of recurrence location and delay. Absence of such enhancements is associated with a fourfold increase in progression-free survival and a 2.5-fold increase in overall survival.

Key Points

? Immediately post-operative MRI reveals contrast enhancement after glioblastoma gross total resection. ? Immediately post-operative micro-nodular and frayed enhancement correlate with early recurrence. ? Absence of micro-nodular/frayed enhancement is associated with 61 weeks’ progression-free survival. ? Absence of micro-nodular/frayed enhancement is associated with 125 weeks’ overall survival.     

MRI assessment of experimental gliomas using 17.6 T

Introduction

Using ultra-high-field contrast-enhanced magnetic resonance imaging (MRI), an increase of field strength is associated with a decrease of T ₁ relaxivity. Yet, the impact of this effect on signal characteristics and contrast-enhanced pathology remains unclear. Hence, we evaluated the potential of a 17.6-T MRI to assess contrast-enhancing parts of experimentally induced rat gliomas compared to 3 T.

Methods

A total of eight tumor-bearing rats were used for MRI assessments either at 17.6 T (four rats) or at 3 T (four rats) at 11 days after stereotactic implantation of F98 glioma cells into the right frontal lobe. T ₁-weighted sequences were used to investigate signal-to-noise-ratios, contrast-to-noise-ratios, and relative contrast enhancement up to 16 min after double-dose contrast application. In addition, tumor volumes were calculated and compared to histology.

Results

The 17.6-T-derived contrast-enhancing volumes were 31.5?±?15.4 mm³ at 4 min, 38.8?±?12.7 mm³ at 8 min, 51.1?±?12.6 mm³ at 12 min, and 61.5?±?10.8 mm³ at 16 min after gadobutrol injection. Corresponding histology-derived volumes were clearly higher (138.8?±?8.4 mm³; P?<?0.01). At 3 T, contrast-enhancing volumes were 85.2?±?11.7 mm³ at 4 min, 107.3?±?11.0 mm³ at 8 min, 117.0?±?10.5 mm³ at 12 min, and 129.1?±?10.0 mm³ at 16 min after contrast agent application. Averaged histology-derived volumes (139.1?±?13.4 mm³) in this group were comparable to the 16-min volume (P _{?16 min}?=?0.38). Compared to ultra-high-field MRI, all 3-T-derived volumes were significantly higher (P?<?0.02).

Conclusion

Compared to 3-T-derived images and histology, tumor volumes were underestimated by approximately 50 % at 17.6 T. Hence, contrast-enhanced 17.6-T MRI provided no further benefits in tumor measurement compared to 3 T.     

Combined magnetic resonance imaging of deep venous thrombosis and pulmonary arteries after a single injection of a blood pool contrast agent

Objective

Agreement rate between magnetic resonance imaging (MRI) and Doppler ultrasound (DUS) for the detection of deep vein thrombosis (DVT) in the lower extremities was attempted by using the intravascular MRI contrast agent gadofosveset trisodium. The potential of this method to detect pulmonary embolism (PE) was also evaluated.

Material and Methods

Forty-three consecutive inpatients with ultrasound-confirmed DVT but no clinical signs of PE were prospectively enrolled in this feasibility study. MRI was performed after a single injection of gadofosveset trisodium. The pulmonary arteries were imaged using a 3D Fast Low Angle Shot (FLASH) gradient recalled echo sequence. Additionally, pulmonary arteries, abdominal veins, pelvic and leg veins were imaged using a fat-suppressed 3D gradient echo Volume Interpolated Breath-hold Examination (VIBE FS).

Results

Gadofosveset trisodium-enhanced MRI detected more thrombi in the pelvic region, upper leg and lower leg than the initial DUS. In addition, PE was detected in 16 of the 43 DVT patients (37%).

Conclusion

This study shows the feasibility of a combined protocol for the MRI diagnosis of DVT and PE using gadofosveset trisodium. This procedure is not only more sensitive in detecting DVT compared to standard DUS, but is also able to detect PE in asymptomatic patients.     

Clinical validation of semi-automated software for volumetric and dynamic contrast enhancement analysis of soft tissue venous malformations on Magnetic Resonance Imaging examination

Objectives

To evaluate venous malformation (VM) volume and contrast-enhancement analysis on magnetic resonance imaging (MRI) compared with diameter evaluation.

Methods

Baseline MRI was undertaken in 44 patients, 20 of whom were followed by MRI after sclerotherapy. All patients underwent short-tau inversion recovery (STIR) acquisitions and dynamic contrast assessment. VM diameters in three orthogonal directions were measured to obtain the largest and mean diameters. Volumetric reconstruction of VM was generated from two orthogonal STIR sequences and fused with acquisitions after contrast medium injection. Reproducibility (interclass correlation coefficients [ICCs]) of diameter and volume measurements was estimated. VM size variations in diameter and volume after sclerotherapy and contrast enhancement before sclerotherapy were compared in patients with clinical success or failure.

Results

Inter-observer ICCs were similar for diameter and volume measurements at baseline and follow-up (range 0.87–0.99). Higher percentages of size reduction after sclerotherapy were observed with volume (32.6?±?30.7 %) than with diameter measurements (14.4?±?21.4 %; P?=?0.037). Contrast enhancement values were estimated at 65.3?±?27.5 % and 84?±?13 % in patients with clinical failure and success respectively (P?=?0.056).

Conclusions

Venous malformation volume was as reproducible as diameter measurement and more sensitive in detecting therapeutic responses. Patients with better clinical outcome tend to have stronger malformation enhancement.

Key points

? Magnetic resonance imaging readily demonstrates diameters and volumes of venous malformations ? MRI diameter calculations are reproducible in estimating the size of venous malformations ? But volumetric models of malformations are more sensitive in detecting therapeutic response ? Dynamic enhancement is also better assessed with automated volumetric software ? Volumetric analysis of malformations offers promise to guide therapy and assess response     

Post-marketing surveillance of gadobutrol for contrast-enhanced magnetic resonance imaging in Japan

Purpose

To evaluate the safety of gadobutrol for magnetic resonance imaging in a prospective, non-interventional, post-marketing surveillance in Japan.

Materials and methods

Gadobutrol was administered in accordance with Japanese prescribing information over a 2-year enrollment period, using a standardized questionnaire to collect information. The primary outcome was the incidence of adverse reactions (ARs) following gadobutrol injection.

Results

Questionnaire data were analyzed for 3337 patients (age, 58.1?±?17.4 years [mean±SD]). Gadobutrol was administered at a dose of 0.10?±?0.02 mL/kg body weight. Thirty-three patients were observed to have 42 ARs suspected to be due to gadobutrol, an incidence proportion of 0.99%; 29 ARs were acute (<1 h post-injection)—including one case of severe acute AR (0.03%). Patient subpopulations (with hepatic, renal, cardiovascular diseases) did not differ markedly in AR proportions categorized by age, sex, presence of comorbidity, or imaging indication. No cases of nephrogenic systemic fibrosis were reported. Investigators rated images as improved or profoundly improved following gadobutrol injection in 91.1% of examinations.

Conclusion

Gadobutrol was well tolerated with a good safety profile in this post-marketing surveillance of a large patient population in Japan.

     

Assessing liver function by liver enhancement during the hepatobiliary phase with Gd-EOB-DTPA-enhanced MRI at 3 Tesla

Objectives

The purpose of this study was to evaluate the usefulness of Gd-EOB-DTPA-enhanced 3-T MRI to determine the hepatic functional reserve expressed by the model for end-stage liver disease (MELD) score.

Methods

A total of 121 patients with normal liver function (NLF; MELD score?≤?10) and 29 patients with impaired liver function (ILF; MELD score?>?10) underwent contrast-enhanced MRI with a hepatocyte-specific contrast agent at 3T. T1-weighted volume interpolated breath-hold examination (VIBE) sequences with fat suppression were acquired before and 20 min after contrast injection. Relative enhancement (RE) between plain signal intensity and contrast-enhanced signal intensity was calculated and was used to determine Gd-EOB-DTPA uptake into the liver parenchyma for patients with different MELD scores.

Results

RE differed significantly (p?≤?0.001) between patients with NLF (87.2?±?29.5 %) and patients with ILF (45.4?±?26.5 %). The optimal cut-off value for RE to differentiate NLF from ILF was 47.7 % (AUC 0.87). This cut-off value showed a sensitivity of 82.8 % and a specificity of 92.7 % for the differentiation of the analysed groups.

Conclusion

Gd-EOB-DTPA uptake in hepatocytes is strongly affected by liver function. Gd-EOB-DTPA-enhanced MRI and assessment of RE during the hepatobiliary phase (HBP) may serve as a useful image-based test in liver imaging for determining regional and global liver function.

Key points

• Hepatic uptake of Gd-EOB-DTPA is strongly affected by liver function.
• Relative enhancement during HBP in GD-EOB-DTPA MRI correlates with the MELD score.
• Assessment of relative enhancement may help improve treatment in routine clinical practice.

     

Combined gadoxetic acid and gadofosveset enhanced liver MRI for detection and characterization of liver metastases

Purpose

To compare gadoxetic acid alone and combined gadoxetic acid/gadofosveset trisodium-enhanced liver MRI for detection of metastases and differentiation of metastases from haemangiomas.

Methods

Ninety-one patients underwent gadoxetic acid-enhanced liver MRI before and after additional injection of gadofosveset. First, two readers retrospectively identified metastases on gadoxetic acid alone enhanced delayed hepatobiliary phase T1-weighted images together with all other MR images (dynamic images, T2-weighted images, diffusion-weighted images). Second, readers assessed additional T1-weighted images obtained after administration of gadofosveset trisodium. For both interpretations, readers rated lesion conspicuity and confidence in differentiating metastases from haemangiomas. Results were compared using alternative free-response receiver-operating characteristic (AFROC) and conventional ROC methods. Histology and follow-up served as reference standard.

Results

There were 145 metastases and 16 haemangiomas. Both readers detected more metastases using combined gadoxetic acid/gadofosveset (reader 1?=?130; reader 2?=?124) compared to gadoxetic acid alone (reader 1?=?104; reader 2?=?103). Sensitivity of combined gadoxetic acid/gadofosveset (reader 1?=?90 %; reader 2?=?86 %) was higher than that of gadoxetic acid alone (reader 1?=?72 %; reader 2?=?71 %, both P?<?0.01). AFROC-AUC was higher for the combined technique (0.92 vs. 0.86, P?<?0.001). Sensitivity for correct differentiation of metastases from haemangiomas was higher for the combined technique (reader 1?=?98 %; reader 2?=?99 % vs. reader 1?=?86 %; reader 2?=?91 %, both P?<?0.01). ROC-AUC was significantly higher for the combined technique (reader 1?=?1.00; reader 2?=?1.00 vs. reader 1?=?0.87; reader 2?=?0.92, both P?<?0.01).

Conclusion

Combined gadoxetic acid/gadofosveset-enhanced MRI improves detection and characterization of liver metastases compared to gadoxetic acid alone.

Key Points

? Combined gadoxetic acid and gadofosveset-enhanced liver MRI significantly improves detection of metastases. ? The combined enhancement technique improves the accuracy to differentiate metastases from haemangiomas. ? Prospective studies need to determine the clinical impact of the combined technique

     

Free-breathing dynamic contrast-enhanced MRI of the abdomen and chest using a radial gradient echo sequence with K-space weighted image contrast (KWIC)

Objectives

To evaluate the feasibility of free-breathing, dynamic contrast-enhanced (DCE) MRI of the abdomen and thorax using the radial-gradient-echo sequence with k-space weighted image contrast (KWIC) reconstruction.

Methods

Institutional review board approval was obtained. Fourteen patients underwent free-breathing radial DCE-MRI. Radial MRI yielded full-frame images by gridding all k-space data and time-resolved subframe images by using KWIC reconstruction technique. Using subframe KWIC images, voxel-wise perfusion maps were created. For comparison, the breath-hold conventional Cartesian 3D-gradient-echo sequence (VIBE) was also performed during the equilibrium phase. The image qualities of radial and conventional VIBE images were compared quantitatively and qualitatively.

Results

Radial DCE-MRI provided high spatial resolution (1.4?×?1.4 mm) and temporal resolution (4.1 s for subframe images) allowing voxel-wise perfusion mapping with negligible motion or streaking artefacts. There were no significant differences in SNR between full-frame radial images and conventional VIBE images (79.08 vs 74.80, P?>?0.05). Overall image quality score of full-frame radial images was slightly lower than that of conventional VIBE images (3.88?±?0.59 vs. 4.31?±?0.97, P?<?0.05), but provided clinically useful images.

Conclusions

The free-breathing radial DCE-MRI can provide high spatial and temporal resolution while maintaining reasonably high image quality and thus is a feasible technique for DCE-MRI in the abdomen and thorax.

Key Points

? Dynamic contrast-enhanced magnetic resonance imaging (DCE) MRI is important in oncological imaging ? Radial MRI with k-space weighted image contrast (KWIC) reconstruction offers potential improvements ? Radial DCE-MRI provides good image quality, reduced artefacts and high spatial/temporal resolution     

Evaluation of monoenergetic late iodine enhancement dual-energy computed tomography for imaging of chronic myocardial infarction

Objectives

To evaluate image quality and diagnostic accuracy of selective monoenergetic reconstructions of late iodine enhancement (LIE) dual-energy computed tomography (DECT) for imaging of chronic myocardial infarction (CMI).

Methods

Twenty patients with a history of coronary bypass surgery underwent cardiac LIE-DECT and late gadolinium enhancement (LGE) magnetic resonance imaging (MRI). LIE-DECT images were reconstructed as selective monoenergetic spectral images with photon energies of 40, 60, 80, and 100 keV and the standard linear blending setting (M_0.6). Images were assessed for late enhancement, transmural extent, signal characteristics and subjective image quality.

Results

Seventy-nine myocardial segments (23 %) showed LGE. LIE-DECT detected 76 lesions. Images obtained at 80 keV and M_0.6 showed a high signal-to-noise ratio (15.9; 15.1), contrast-to-noise ratio (4.2; 4.0) and sensitivity (94.9 %; 92.4 %) while specificity was identical (99.6 %). Differences between these series were not statistically significant. Transmural extent of LIE was overestimated in both series (80 keV: 40 %; M_0.6: 35 %) in comparison to MRI. However, observers preferred 80 keV in 13/20 cases (65 %, κ?=?0.634) over M_0.6 (4/20 cases) regarding subjective image quality.

Conclusions

Post-processing of LIE-DECT data with selective monoenergetic reconstructions at 80 keV significantly improves subjective image quality while objective image quality shows no significant difference compared to standard linear blending.

Key Points

? Late enhancement dual-energy CT allows for detection of chronic myocardial infarction. ? Monoenergetic reconstructions at 80 keV significantly improve subjective image quality. ? 80 keV and standard linear blending reconstructions show no significant differences. ? Extent of CMI detected with LIE-DECT is overestimated compared with MRI.     

Measuring hepatic functional reserve using low temporal resolution Gd-EOB-DTPA dynamic contrast-enhanced MRI: a preliminary study comparing galactosyl human serum albumin scintigraphy with indocyanine green retention

Objective

To investigate if tracer kinetic modelling of low temporal resolution dynamic contrast-enhanced (DCE) MRI with Gd-EOB-DTPA could replace technetium-99 m galactosyl human serum albumin (GSA) single positron emission computed tomography (SPECT) and indocyanine green (ICG) retention for the measurement of liver functional reserve.

Methods

Twenty eight patients awaiting liver resection for various cancers were included in this retrospective study that was approved by the institutional review board. The Gd-EOB-DTPA MRI sequence acquired five images: unenhanced, double arterial phase, portal phase, and 4 min after injection. Intracellular contrast uptake rate (UR) and extracellular volume (Ve) were calculated from DCE-MRI, along with the ratio of GSA radioactivity of liver to heart-plus-liver and per cent of cumulative uptake from 15–16 min (LHL15 and LU15, respectively) from GSA-scintigraphy. ICG retention at 15 min, Child–Pugh cirrhosis score (CPS) and postoperative Inuyama fibrosis criteria were also recorded. Statistical analysis was with Spearman rank correlation analysis.

Results

Comparing MRI parameters with the reference methods, significant correlations were obtained for UR and LHL15, LU15, ICG15 (all 0.4–0.6, P?<?0.05); UR and CPS (-0.64, P?<?0.001); Ve and Inuyama (0.44, P?<?0.05).

Conclusion

Measures of liver function obtained by routine Gd-EOB-DTPA DCE-MRI with tracer kinetic modelling may provide a suitable method for the evaluation of liver functional reserve.

Key points

? Magnetic resonance imaging (MRI) provides new methods of measuring hepatic functional reserve. ? DCE-MRI with Gd-EOB-DTPA offers the possibility of replacing scintigraphy. ? The analysis method can be used for preoperative liver function evaluation.     

Added value of subtraction imaging in detecting arterial enhancement in small (<3 cm) hepatic nodules on dynamic contrast-enhanced MRI in patients at high risk of hepatocellular carcinoma

Objectives

To determine the importance of arterial enhancement in diagnosing small (<3 cm) hepatocellular carcinomas (HCCs) and to evaluate the added value of dynamic subtraction magnetic resonance imaging (MRI) in detecting arterial enhancement in small (<3 cm) hepatic nodules in high-risk patients.

Methods

Eighty-six patients with 135 pathologically confirmed small (<3 cm) hepatic nodules (104 HCCs, 31 benign nodules) underwent MRI before curative surgery. Arterial enhancement was determined by three methods: (1) visual assessment of the arterial phase alone, (2) visual comparison of the arterial phase with the unenhanced phase and (3) additional review of subtraction images. The diagnostic performance of each method was calculated and compared using generalised estimating equations analysis.

Results

Arterial enhancement demonstrated high positive predictive value (PPV) (96.5–98.9 %) and specificity (90.3–96.8 %), but low negative predictive value (NPV) (54.6–62.5 %) and intermediate sensitivity (76–79.8 %) for diagnosing small HCCs. Diagnostic performance was highest for subtraction imaging. There were significant differences among the three methods in sensitivity (P?=?0.04), accuracy (P?=?0.044), PPV (P?<?0.001) and NPV (P?=?0.024), but not in specificity (P?=?0.167).

Conclusion

The accurate detection of arterial enhancement in small hepatic nodules is important for diagnosing HCC and may be enhanced by subtraction imaging.

Key Points

? Arterial enhancement in small hepatic nodules indicates a high probability of malignancy ? Dynamic subtraction MRI can enable more accurate detection of arterial enhancement ? Subtraction imaging could lead to earlier diagnosis of hepatocellular carcinoma ? More timely care for patients might be provided     

Dynamic contrast-enhanced and ultra-high-resolution breast MRI at 7.0 Tesla

Objective

To assess the feasibility of 7-T contrast-enhanced breast MRI in patients with suspicious masses.

Methods

Twenty patients with 23 suspicious breast masses on conventional imaging (mean size 13 mm, range 5–27 mm) were examined at 7 T. The MRI protocol included a dynamic series with injection of 0.1 mmol/kg gadobutrol (seven consecutive 3D T1-weighted gradient echo sequences, resolution 1?×?1?×?2 mm³, temporal resolution 63 s) and ultra-high-resolution imaging (T1-weighted 3D gradient echo sequence, resolution 0.45?×?0.57?×?0.45 mm³). Two observers (R1 and R2) independently judged the examinations on image quality and classified lesions according to BI-RADS. The added value of ultra-high-resolution imaging was assessed.

Results

The image quality was deemed excellent in 1 and 0, good in 10 and 12, sufficient in 8 and 8, and insufficient in 1 and 0 for R1 and R2 respectively. Twenty of the 23 lesions were identified at 7-T MRI by both observers. All histopathologically proven malignant lesions (n?=?19) were identified and classified as BI-RADS-MRI 4 or 5. Ultra-high-resolution imaging increased reader confidence in 88 % (R1) and 59 % (R2) of acquisitions.

Conclusion

The study shows the feasibility of dynamic contrast-enhanced 7-T breast MRI, where all malignant mass lesions were identified by two observers.

Key Points

? Magnetic resonance imaging is important in the evaluation of breast cancer. ? Recently, 7-T MRI has become available. ? The 7-T dynamic contrast-enhanced breast MRI is feasible in patients. ? The 7-T breast examinations are amenable to evaluation according to BI-RADS.     

Determination of optimal intravenous contrast agent iodine dose for the detection of liver metastasis at 80-kVp CT

Objectives

To determine the optimal iodine mass (IM) to achieve a 50-HU increase in hepatic attenuation for the detection of liver metastasis based on total body weight (TBW) or body surface area (BSA) at 80-kVp computed tomography (CT) imaging of the liver.

Methods

One-hundred and fifty patients who underwent contrast-enhanced CT at 80-kVp were randomised into three groups: 0.5 gI/kg, 0.4 gI/kg and 0.3 gI/kg. Portal venous phase images were evaluated for hepatic parenchymal enhancement (?HU) and visualisation of liver metastasis. Iodine mass per BSA (gI/m²) calculated in individual patients were evaluated.

Results

Mean ?HU for the 0.5 gI/kg group (84.2 HU) was higher than in the 0.4 gI/kg (66.1 HU) and 0.3 gI/kg (53.7 HU) groups (P?<?0.001). Linear correlation equations between ?HU and IM per TBW or BSA are ?HU?=?7.0?+?153.0?×?IM/TBW (r?=?0.73, P?<?0.001) and ?HU?=?11.4?+?4.0?×?IM/BSA (r?=?0.75, P?<?0.001), respectively. The three groups were comparable for the visualisation of hepatic metastases.

Conclusions

The iodine mass to achieve a 50-HU increase in hepatic attenuation at 80-kVp CT was estimated to be 0.28 gI/kg of body weight or 9.6 gI/m² of body surface area.

Key Points

? Hepatic enhancement is expressed as ?HU?=?7.0?+?153.0?×?IM [g]/TBW [kg]. ? Hepatic enhancement is expressed as ?HU?=?11.4?+?4.0?×?IM [g]/BSA [m ² ]. ? Essential iodine dose at 80-kVp CT was 0.28 gI/kg or 9.6 gI/m ² .     

Diffusion magnetic resonance imaging with gadofosveset trisodium as a negative contrast agent for lymph node metastases assessment

Purpose

The aim of this study was to assess the feasibility of using intravenously administered gadofosveset trisodium as a negative contrast agent for lymph node (LN) assessment with diffusion-weighted imaging (DWI) using a VX2 tumor model in rabbits.

Materials and methods

VX2 cells were injected in the right hind limb of five Japanese white rabbits to induce ipsilateral popliteal LN metastasis. DWI was performed before and every 7.5 min (until 1 h) after intravenous gadofosveset trisodium administration, at 1.5 T. Signal intensities (SIs) of right (metastatic) and left (nonmetastatic) popliteal LNs at each time point were measured and compared to each other using two-sided unpaired t-tests.

Results

The SIs of metastatic lymph nodes were significantly higher (P < 0.05) than those of nonmetastatic LNs at each time point after intravenous gadofosveset trisodium administration. Although the SI of metastatic LNs was significantly higher (P = 0.0237) than that of nonmetastatic LNs before contrast injection, this difference became even more significant (P ?? 0.0105) after gadofosveset trisodium administration.

Conclusion

The SI of metastatic LNs at DWI is less suppressed than that of nonmetastatic LNs after the intravenous administration of gadofosveset trisodium. Therefore, intravenously administered gadofosveset trisodium shows promise for use as a negative contrast agent for discriminating metastatic from nonmetastatic LNs at DWI.