Clinical outcome and predictors of treatment response in foam sodium tetradecyl sulfate sclerotherapy of venous malformations

Objectives

To evaluate clinical outcomes and their predictors in patients with venous malformation (VM) treated with foam sodium tetradecyl sulfate (STS) sclerotherapy.

Methods

We retrospectively evaluated clinical outcomes of foam STS sclerotherapy in 86 patients with 91 VMs to assess reduction in pain and mass after treatment. Univariate and multivariate analysis was performed to determine possible predictors of clinical outcome with foam STS sclerotherapy.

Results

A positive response of 49.5 % in pain reduction and 52.7 % in mass reduction was observed. The numerical rating scale (NRS) score improved from 4.36?±?2.64 to 1.74?±?1.57, and VM mass volume decreased to 41.7?±?35.52 % of the initial size. On multivariate analysis, a high baseline NRS score (odds ratio: 1.12, 95 % confidence interval: 1.09–1.15) and VM location in the trunk versus the head and neck (odds ratio: 1.30, 95 % confidence interval: 1.00–1.69) were positive predictors of pain improvement. Minor complications occurred in 11 (12.1 %) patients and recurrence in 12 (13.2 %) patients.

Conclusions

Foam STS sclerotherapy is an effective treatment in venous malformation, with low complication risk. A high baseline NRS score and location in the trunk versus the head and neck were positive predictors in improvement of pain.

Key Points

? Foam STS sclerotherapy is effective in VM, with low risk of complications. ? Relief of pain tends to be dramatic in patients with severe pain. ? Location of VM is a predictor of pain improvement. ? The presence of a draining vein does not affect foam sclerotherapy.

     

Impact of contrast injection and stent-graft implantation on reproducibility of volume measurements in semiautomated segmentation of abdominal aortic aneurysm on computed tomography

Purpose

To assess the impact of contrast injection and stent-graft implantation on feasibility, accuracy, and reproducibility of abdominal aortic aneurysm (AAA) volume and maximal diameter (D-max) measurements using segmentation software.

Materials and methods

CT images of 80 subjects presenting AAA were divided into four equal groups: with or without contrast enhancement, and with or without stent-graft implantation. Semiautomated software was used to segment the aortic wall, once by an expert and twice by three readers. Volume and D-max reproducibility was estimated by intraclass correlation coefficients (ICC), and accuracy was estimated between the expert and the readers by mean relative errors.

Results

All segmentations were technically successful. The mean AAA volume was 167.0?±?82.8 mL and the mean D-max 55.0?±?10.6 mm. Inter- and intraobserver ICCs for volume and D-max measurements were greater than 0.99. Mean relative errors between readers varied between ?1.8?±?4.6 and 0.0?±?3.6 mL. Mean relative errors in volume and D-max measurements between readers showed no significant difference between the four groups (P?≥?0.2).

Conclusion

The feasibility, accuracy, and reproducibility of AAA volume and D-max measurements using segmentation software were not affected by the absence of contrast injection or the presence of stent-graft.

Key points

? AAA volumetry by semiautomated segmentation is accurate on CT following endovascular repair. ? AAA volumetry by semiautomated segmentation is accurate on unenhanced CT. ? Standardization of the segmentation technique maximizes the reproducibility of volume measurements.     

Contrast-enhanced ultrasound of focal nodular hyperplasia: a matter of size

Objectives

To assess the contrast-enhanced ultrasound (CEUS) frequencies of centrifugal enhancement, spoke-wheel sign and central scar in focal nodular hyperplasia (FNH) as a function of lesion size.

Methods

Ninety-four FNHs were retrospectively reviewed to assess their largest diameter and enhancement pattern, including centrifugal enhancement from one central artery, spoke-wheel sign, diffuse or centripetal enhancement, central scar and late-phase washout.

Results

Mean FNH-lesion size was 3.7?±?2.1 cm. Only 43.6 % of FNHs had centrifugal enhancement, with a spoke-wheel pattern (23.4 %) or without (20.2 %), while 56.4 % showed diffuse or centripetal enhancement. Centrifugal enhancement was observed in 73.9 % of FNHs ≤3.1 cm and 14.6 % of FNHs >3.1 cm (P?–4). Size and frequency of centrifugal enhancement were negatively correlated (r?=?–0.57, P?–4). The spoke-wheel pattern was also seen more frequently in smaller (37 %) than in larger FNHs (10.4 %) (P?–3). Late-phase washout was described in 5.3 % of FNHs and was not size-dependent. Lesions with a central scar were larger than those without, respectively, 5.7?±?1.7 and 3.6?±?2.0 cm (P?=?0.012).

Conclusions

Typical centrifugal enhancement yielding a confident FNH diagnosis is seen significantly more frequently when the lesion is ≤3.1 cm.

Key Points

? CEUS yields confident diagnoses of FNHs ≤3.1 cm ? The larger the FNH, the lower the diagnostic sensitivity of CEUS ? Final diagnosis of FNHs >3.1 cm should be obtained with MRI not CEUS     

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.     

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.

     

Salvage assessment with cardiac MRI following acute myocardial infarction underestimates potential for recovery of systolic strain

Objectives

Our aim was to evaluate the relationship between the degree of salvage following acute ST elevation myocardial infarction (STEMI) and subsequent reversible contractile dysfunction using cardiac magnetic resonance (CMR) imaging.

Methods

Thirty-four patients underwent CMR examination 1–7 days after primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at 1 year. The ischaemic area-at-risk (AAR) was assessed with T2-weighted imaging and myocardial necrosis with late gadolinium enhancement. Myocardial strain was quantified with complementary spatial modulation of magnetisation (CSPAMM) tagging.

Results

Ischaemic segments with poor (<25 %) or intermediate (26–50 %) salvage index were associated with worse Eulerian circumferential (Ecc) strain immediately post-PPCI (?9.1 %?±?0.6, P?=?0.033 and ?11.8 %?±?1.3, P?=?0.003, respectively) than those with a high (51–100 %) salvage index (?14.4 %?±?1.3). Mean strain in ischaemic myocardium improved between baseline and follow-up (?10.1 %?±?0.5 vs. ?16.2 %?±?0.5 %, P?<?0.0001). Segments with poor salvage also showed an improvement in strain by 1 year (?9.1 %?±?0.6 vs. ?15.3 %?±?0.6, P?=?0.033) although they remained the most functionally impaired.

Conclusions

Partial recovery of peak systolic strain following PPCI is observed even when apparent salvage is less than 25 %. Late gadolinium enhancement (LGE) may not equate to irreversibly injured myocardium and salvage assessment performed within the first week of revascularisation may underestimate the potential for functional recovery.

Key Points

? MRI can measure how much myocardium is damaged after a heart attack. ? Heart muscle that appears initially non-viable may sometimes partially recover. ? Enhancement around the edges of infarcts may resolve over time. ? Evaluating new cardio-protective treatments with MRI requires appreciation of its limitations.     

Association of trochlear dysplasia with degenerative abnormalities in the knee: data from the Osteoarthritis Initiative

Objective

To evaluate trochlear morphology as a potential risk factor for patellofemoral osteoarthritis, determined by morphological and quantitative measurements of cartilage degeneration using 3-T magnetic resonance imaging (MRI) of the knee.

Materials and methods

MRI of the right knees of 304 randomly selected subjects, aged 45–60 years, from the Osteoarthritis Initiative (OAI) progression cohort were screened for trochlear dysplasia, defined by an abnormal trochlear depth. Out of 304 subjects, n?=?85 demonstrated a shallow trochlea (depth ≤3 mm; 28 %). In these, and also in a random sample of controls with normal trochlear depth (n?=?50), the facet ratio and the sulcus angle were calculated and knee structural abnormalities were assessed by using a modified Whole Organ MR Imaging Score (WORMS). Cartilage segmentation was performed and T₂ relaxation times and patellar cartilage volume were determined. ANOVA and multivariate regression models were used for statistical analysis of the association of MRI structural measures and trochlear morphology.

Results

Knees with a shallow trochlea showed higher patellofemoral degeneration (WORMS mean ± standard deviation, 11.2?±?0.5 versus 5.7?±?0.6; multivariate regression, P?<?0.001) and lower patellar cartilage volume than controls (900?±?664 mm³ versus 1,671?±?671 mm³; P?<?0.001). Knees with an abnormal medial-to-lateral facet ratio (<0.4) showed increased patellofemoral WORMS scores (12.3?±?0.9 versus 8.3?±?0.5; P?<?0.001). Knees with an abnormal sulcus angle (>170°) also showed increased WORMS scores (12.2?±?1.1 versus 8.6?±?0.6; P?=?0.003). T₂ values at the patella were significantly lower in the dysplasia group with a shallow trochlea. However, significance was lost after adjustment for cartilage volume (P?=?0.673).

Conclusion

Trochlear dysplasia, defined by a shallow trochlea, was associated with higher WORMS scores and lower cartilage volume, indicating more advanced osteoarthritis at the patellofemoral joint.     

Grading of Cerebral Glioma with Multiparametric MR Imaging and 18F-FDG-PET: Concordance and Accuracy

Objectives

To retrospectively evaluate concordance rates and predictive values in concordant cases among multiparametric MR techniques and FDG-PET to grade cerebral gliomas.

Methods

Multiparametric MR imaging and FDG-PET were performed in 60 consecutive patients with cerebral gliomas (12 low-grade and 48 high-grade gliomas). As the dichotomic variables, conventional MRI, minimum apparent diffusion coefficient in diffusion-weighted imaging, maximum relative cerebral blood volume ratio in perfusion-weighted imaging, choline/creatine ratio and (lipid and lactate)/creatine ratio in MR spectroscopy, and maximum standardised uptake value ratio in FDG-PET in low- and high-grade gliomas were compared. Their concordance rates and positive/negative predictive values (PPV/NPV) in concordant cases were obtained for the various combinations of multiparametric MR techniques and FDG-PET.

Results

There were significant differences between low- and high-grade gliomas in all techniques. Combinations of two, three, four, and five out of the five techniques showed concordance rates of 77.0?±?4.8 %, 65.5?±?4.0 %, 58.3?±?2.6 % and 53.3 %, PPV in high-grade concordant cases of 97.3?±?1.7 %, 99.1?±?1.4 %, 100.0?±?0 % and 100.0 % and NPV in low-grade concordant cases of 70.2?±?7.5 %, 78.0?±?6.0 %, 80.3?±?3.4 % and 80.0 %, respectively.

Conclusion

Multiparametric MR techniques and FDG-PET have a concordant tendency in a two-tiered classification for the grading of cerebral glioma. If at least two examinations concordantly indicated high-grade gliomas, the PPV was about 95 %.

Key Points

? Modern imaging techniques can help predict the aggressiveness of cerebral gliomas. ? Multiparametric MRI and FDG-PET have a concordant tendency to grade cerebral gliomas. ? Their high-grade concordant cases revealed at least 95 % positive predictive values. ? Their low-grade concordant cases revealed about 70–80 % negative predictive values.     

Multiple antiplatelet therapy contributes to the reversible high signal spots on diffusion-weighted imaging in elective coiling of unruptured cerebral aneurysm

Introduction

Our aim was to systematically investigate radiographic characteristics and outcome of diffusion-weighted imaging (DWI) changes in the elective coiling of unruptured cerebral aneurysm with analyzing the correlation of antiplatelet therapy (APT).

Methods

In a total of 34 consecutive patients with unruptured cerebral aneurysms initially treated by coiling without stent assist, 26 (76.5 %) had DWI changes with 91 high signal spots within 24–48 h after the procedure. We recorded DWI parameters (location, volume, mean, and minimum values of the apparent diffusion coefficient: expressed as ADC_AVE and ADC_MIN) for each lesion, and evaluated its radiographic outcome on conventional MRI at follow-up (interval, 58.4?±?37.2 days) in the modes of APT.

Results

All patients with DWI high spots had no clinical symptoms. There was a strong correlation between ADC_AVE and ADC_MIN (r?=?0.82, p?<?0.0001). The mean ADC_AVE and rADC_AVE were 0.74?±?0.14?×?10^?3?mm²/s and 87?±?10 %. DWI high spots were small with a mean volume of 0.13?±?0.12 cm³, ranging from 0.04 to 0.86 cm³. A negative correlation was observed between the volume and values of ADC_AVE (r?=??0.48, p?<?0.0001). The DWI volume was significantly larger in single APT than in multiple (0.15?±?0.14 versus 0.10?±?0.07 cm³, p?=?0.0091). The permanent signal change was more observed in single APT than in multiple (24.5 % versus 5.2 %, p?=?0.02).

Conclusion

DWI high spots after elective coiling were small without significant decrease of ADC, and do not correspond to brain infarction. Periprocedural use of multiple antiplatelet agents is expected to reduce the volume of thromboembolism and permanent tissue damages.     

Quantitative assessment of right ventricular function and pulmonary regurgitation in surgically repaired tetralogy of Fallot using 256-slice CT: comparison with 3-Tesla MRI

Objectives

To compare 256-slice cardiac computed tomography (CCT) with cardiac magnetic resonance (CMR) imaging to assess right ventricular (RV) function and pulmonary regurgitant fraction (PRF) in patients with repaired tetralogy of Fallot (TOF).

Methods

Thirty-three consecutive patients with repaired TOF underwent retrospective ECG-gated CCT and 3-Tesla CMR. RV and left ventricular (LV) end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were measured using CCT and CMR. PRF-CCT (%) was defined as (RVSV???LVSV)/RVSV. PRF-CMR (%) was measured by the phase-contrast method. Repeated measurements were performed to determine intra- and interobserver variability.

Results

CCT measurements, including PRF, correlated highly with the CMR reference (r?=?0.71–0.96). CCT overestimated RVEDV (mean difference, 17.1?±?2.9 ml), RVESV (12.9?±?2.1 ml) and RVSV (4.2?±?2.0 ml), and underestimated RVEF (?2.6?±?1.0 %) and PRF (?9.1?±?2.0 %) compared with CMR. The limits of agreement between CCT and CMR were in a good range for all measurements. The variability in CCT measurements was lower than those in CMR. The estimated effective radiation dose was 7.6?±?2.6 mSv.

Conclusions

256-slice CCT can assess RV function and PRF with relatively low dose radiation exposure in patients with repaired TOF, but overestimates RV volume and underestimates PRF.

Key points

? 256-slice CT assessment of RV function is highly reproducible in repaired TOF. ? Pulmonary regurgitation can be evaluated by biventricular systolic volume difference. ? CT overestimates RV volume and underestimates pulmonary regurgitation, compared with MRI.     

Clinical impact of hyperattenuation of adrenal glands on contrast-enhanced computed tomography of polytraumatised patients

Objective

To evaluate the prognostic value of hyperattenuating adrenal glands on contrast-enhanced CT of polytraumatised patients.

Methods

Two hundred ninety-two patients (195 men and 97 women, mean age 45.3?±?23.3 years) were included in this retrospective study. CT examinations were performed 60 s after intravenous injection of contrast material. Image analysis was performed by two radiologists. Patients were assigned to one of two groups according to the attenuation of the adrenal gland [group 1: adrenal glands ≥ inferior vena cava (IVC); group 2: adrenal glands < IVC].

Results

Eighteen patients (42.2 years?±?24.2) were assigned to group 1 and 274 patients (48.4 years?±?22.4) to group 2. The average adrenal density was 150.8?±?36.1 HU in group 1 and 83.7?±?23.6 HU in group 2 (P?<?0.0001). Eight of the 18 patients in group 1 (44.4 %) and 33 of the 274 patients in group 2 (12.4 %) died during hospitalisation (P?<?0.05). Mean adrenal enhancement was significantly higher in patients who died (101.9?±?40.6 HU) compared with survivors (86.1?±?27.0 HU; P?<?0.001).

Conclusion

Hyperattenuation of adrenal glands is associated with a higher mortality rate in polytraumatised patients and may serve as a predictor of poor clinical outcome.

Key points

? Hyperattenuating adrenal glands can be observed in 6.2 % of polytraumatised patients. ? Hyperattenuating adrenal glands indicate poor clinical outcome in polytraumatised patients. ? In polytraumatised patients, hyperattenuating adrenal glands are associated with a high mortality rate. ? Adrenal enhancement is higher amongst patients who died than amongst survivors.     

The value of time-intensity curves obtained after microbubble contrast agent injection to discriminate responders from non-responders to anti-inflammatory medication among patients with Crohn’s disease

Objective

To assess the value of time-intensity curves obtained after sulphur hefluoride-filled microbubble contrast agent injection to discriminate responders from non-responders among patients with Crohn’s disease (CD).

Methods

Forty-three patients (29 male and 14 female; mean age?±?SD, 48.5?±?17.17 years) with initial diagnosis of active CD were recruited. In each patient, the therapeutic outcome was assessed after 12 weeks from the beginning of pharmacologic treatment. The terminal ileal loop was scanned after sulphur hexafluoride-filled microbubble injection, and the digital cine-clip registered during the first-pass dynamic enhancement was quantified in gray-scale levels. The percentage of maximal enhancement, time to peak enhancement, and area under the time-intensity curve in responders vs. non-responders were compared by Mann-Whitney U non-parametric test.

Results

Responders (n?=?25 patients) vs. non-responders (n?=?18) differed in the area under the time-intensity curve (621.58?±?374.53 vs. 1,199.64?±?386.39 P?<?0.05), while they did not differ in percentage of maximal enhancement (41.26?±?15.22 vs. 43.17?±?4.41, P?=?0.25) and time to peak enhancement (11.31?±?3.06 vs. 10.12?±?3.47, P?=?0.15).

Conclusions

The area under the time-intensity curve obtained after microbubble injection was the only parameter to discriminate responders from non-responders among patients with CD during pharmacologic treatment.

Key Points

? Dynamic ultrasound using microbubble contrast agents can help assess inflammatory bowel disease ? Time-intensity curves can assess therapeutic outcome in Crohn’s disease (CD) ? The area under the time-intensity curve differentiates responders from non-responders during pharmacological treatment     

Heritability, determinants and reference values of renal length: a family-based population study

Objectives

In this population-based study, reference values were generated for renal length, and the heritability and factors associated with kidney length were assessed.

Methods

Anthropometric parameters and renal ultrasound measurements were assessed in randomly selected nuclear families of European ancestry (Switzerland). The adjusted narrow sense heritability of kidney size parameters was estimated by maximum likelihood assuming multivariate normality after power transformation. Gender-specific reference centiles were generated for renal length according to body height in the subset of non-diabetic non-obese participants with normal renal function.

Results

We included 374 men and 419 women (mean ± SD, age 47?±?18 and 48?±?17 years, BMI 26.2?±?4 and 24.5?±?5 kg/m², respectively) from 205 families. Renal length was 11.4?±?0.8 cm in men and 10.7?±?0.8 cm in women; there was no difference between right and left renal length. Body height, weight and estimated glomerular filtration rate (eGFR) were positively associated with renal length, kidney function negatively, age quadratically, whereas gender and hypertension were not. The adjusted heritability estimates of renal length and volume were 47.3?±?8.5 % and 45.5?±?8.8 %, respectively (P?<?0.001).

Conclusion

The significant heritability of renal length and volume highlights the familial aggregation of this trait, independently of age and body size. Population-based references for renal length provide a useful guide for clinicians.

Key Points

? Renal length and volume are heritable traits, independent of age and size. ? Based on a European population, gender-specific reference values/percentiles are provided for renal length. ? Renal length correlates positively with body length and weight. ? There was no difference between right and left renal lengths in this study. ? This negates general teaching that the left kidney is larger and longer.     

Albumin-binding MR blood pool contrast agent improves diagnostic performance in human brain tumour: comparison of two contrast agents for glioblastoma

Objective

We qualitatively and quantitatively compared MRI enhancement obtained with gadofosveset, an albumin-binding blood-pool contrast agent, and with gadobutrol, an extracellular contrast agent, in patients with glioblastoma.

Methods

Thirty-five patients (25 men; 64?±?14 years) with histologically proven glioblastoma underwent MRI including pre- and post-contrast T1-weighted SE images acquired 5 min after gadobutrol (0.1 mmol/kg) and, 48 h later, images acquired with identical parameters 5 min and 3, 6, and 24 h after gadofosveset (0.03 mmol/kg). Lesion extent, delineation, internal morphology, multifocality, and global diagnostic preference were evaluated quantitatively for the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and contrast enhancement (CE).

Results

Mean values of SNR, CNR, and tumour CE were highest 6 h after gadofosveset. Multifocality was seen in 17 (48.6 %) patients; additional lesions had stronger enhancement 6 h after gadofosveset in 12 patients (70.6 %). In 21 (60 %) patients, radiologists’ global preference was highest in images acquired 6 h after gadofosveset (kappa?=?0.764). In 22 patients (62.8 %), all qualitative endpoints were better at 5 min after gadobutrol than in images acquired 5 min after gadofosveset injection.

Conclusions

Gadobutrol gives significant tumour enhancement in early postcontrast imaging. However, images acquired 6 h after gadofosveset injection have significantly better diagnostic information endpoints and contrast enhancement.

Key Points

? We compared MRI enhancement with gadofosveset and gadobutrol in patients with glioblastoma. ? Gadobutrol provides better enhancement in early enhanced imaging at 5 min. ? Gadofosveset at 6 h post-injection provides optimal enhancement and diagnostic information endpoints. ? Gadofosveset is feasible for diagnostic quality contrast-enhanced MRI in glioblastoma. ? The contrast medium dose can be reduced without disminishing the image quality using gadofosveset.     

Diffusion-weighted imaging of focal renal lesions: a meta-analysis

Objectives

Contrast-enhanced MRI can only distinguish to a limited extent between malignant and benign focal renal lesions. The aim of this meta-analysis is to review renal diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values for different renal lesions that can be applied in clinical practice.

Methods

A PubMed search was performed to identify relevant articles published 2004–2011 on renal DWI of focal renal lesions. ADC values were extracted by lesion type to determine whether benign or malignant. The data table was finalised in a consensus read. ADC values were evaluated statistically using meta-regression based on a linear mixed model. Two-sided P value <5 % indicated statistical significance.

Results

The meta-analysis is based on 17 studies with 764 patients. Renal cell carcinomas have significant lower ADC values than benign tissue (1.61?±?0.08?×?10^-3 mm²/s vs 2.10?±?0.09?×?10^-3 mm²/s; P?<?0.0001). Uroepithelial malignancies can be differentiated by lowest ADC values (1.30?±?0.11?×?10^-3 mm²/s). There is a significant difference between ADC values of renal cell carcinomas and oncocytomas (1.61?±?0.08?×?10^-3 mm²/s vs 2.00?±?0.08?×?10^-3 mm²/s; P?<?0.0001).

Conclusions

Evaluation of ADC values can help to determine between benign and malignant lesions in general but also seems able to differentiate oncocytomas from malignant tumours, hence potentially reducing the number of unnecessarily performed nephrectomies.

Key Points

? This meta-analysis assesses the role of diffusion-weighted MRI in renal lesions. ? ADC values obtained by DW MRI have been compared for different renal lesions. ? ADC values can help distinguish between benign and malignant tumours. ? Differentiating oncocytomas from malignant tumours can potentially reduce inappropriate nephrectomies.     

Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients

Objectives

To evaluate the clinical outcomes and safety of radiofrequency (RF) ablation for benign non-functioning thyroid nodules over a 4-year follow-up.

Methods

We evaluated 126 benign non-functioning thyroid nodules of 111 patients treated with RF ablation and followed-up more than 3 years. RF ablation was performed using the Cool-Tip RF system and an internally cooled electrode. Nodule volume and cosmetic and symptom scores were evaluated before treatment and during follow-up. Complications and factors related to efficacy were evaluated.

Results

The mean follow-up duration was 49.4?±?13.6 months. Thyroid nodule volume decreased significantly, from 9.8?±?8.5 ml before ablation to 0.9?±?3.3 ml (P?<?0.001) at final evaluation: a mean volume reduction of 93.4?±?11.7 %. The mean cosmetic (P?<?0.001) and symptom scores (P?<?0.001) improved significantly. Factors related to efficacy were initial solidity and volume. The overall recurrence rate was 5.6 % (7/126). The overall complication rate was 3.6 % (4/111).

Conclusions

RF ablation was effective in shrinking benign thyroid nodules and in controlling nodule-related problems over a 4-year follow-up. There were no life-threatening complications or sequelae. Therefore, RF ablation can be used as a non-surgical treatment for patients with benign non-functioning thyroid nodules.

Key Points

? Radiofrequency (RF) ablation provides a non-surgical option for benign non-functioning thyroid nodules ? RF ablation reduced non-functioning thyroid nodular volume by 93.5 % after 49 months ? Initial solidity and volume influenced the efficacy of RF ablation ? Larger thyroid nodules required more treatment sessions to achieve appropriate volume reduction ? Complete treatment of the periphery of the nodule is important in preventing marginal regrowth     

Precision of pulmonary vein diameter measurements assessed by CE-MRA and steady-state-free precession imaging

Objective

Pulmonary vein (PV) diameter assessment is important for planning and follow-up of PV ablation in atrial fibrillation. Therefore, the aim of our study was to evaluate inter- and intraobserver reliability of PV diameter measurements by contrast-enhanced magnetic resonance angiography (CE-MRA) and ECG-gated 2D multislice unenhanced steady-state-free precession sequences (multislice SSFP).

Methods

Sixty PV diameters in 17 consecutive patients were measured in transverse and coronal orientation with CE-MRA and multislice SSFP by two observers. Statistics to evaluate inter- and intraobserver reliability included Bland-Altman analysis and F-test.

Results

Intraobserver limits of agreement (LAG) ranged between ±0.50 cm (transverse) and ±0.86 cm (coronal) for CE-MRA versus ±0.40 cm (transverse) and ±0.67 cm (coronal) for multislice SSFP. Interobserver agreement showed LAG ranging between ±0.59 cm (transverse) and ±0.83 cm (coronal) for CE-MRA versus ±0.34 cm (transverse) and ±0.75 cm (coronal) for multislice SSFP. Intra- and interobserver variances did not reveal significant differences between CE-MRA and multislice SSFP in any orientation (all p-values >0.05).

Conclusion

Multislice SSFP and CE-MRA enable comparable precision of PV diameter measurements. However, both methods reveal a wide range of intra- and interobserver agreement, which has to be thoroughly considered in clinical use.

Key Points

? Unenhanced magnetic resonance imaging can now provide measurement of pulmonary vein diameters ? Steady-state-free precession offers a new method of performing unenhanced MR imaging ? Both unenhanced and enhanced MRI measurements show wide intra- and interobserver variation ? PV diameter measurements assessed by MRI have to be interpreted with care ? Nevertheless, unenhanced MRI might replace some CT examinations for pulmonary vein demonstration     

Assessment of irradiated brain metastases using dynamic contrast-enhanced magnetic resonance imaging

Introduction

The purpose of this study was to evaluate the effect of stereotactic radiosurgery (SRS) on cerebral metastases using the transfer constant (K _trans) assessed by dynamic contrast-enhanced (DCE) MRI. Furthermore, we aimed to evaluate the ability of K _trans measurements to predict midterm tumor outcomes after SRS.

Methods

The study received institutional review board approval, and informed consent was obtained from all subjects. Twenty-six adult patients with a total of 34 cerebral metastases underwent T1-weighted DCE MRI in a 1.5-T magnet at baseline (prior to SRS) and 4–8 weeks after treatment. Quantitative analysis of DCE MRI was performed by generating K _trans parametric maps, and region-of-interest-based measurements were acquired for each metastasis. Conventional MRI was performed at least 16 weeks after SRS to assess midterm tumor outcome using volume variation.

Results

The mean (±SD) K _trans value was 0.13?±?0.11 min^?1 at baseline and 0.08?±?0.07 min^?1 after 4–8 weeks post-treatment (p?<?0.001). The mean (±SD) total follow-up time was 7.9?±?4.7 months. Seventeen patients (22 lesions) underwent midterm MRI. Of those, nine (41 %) lesions had progressed at the midterm follow-up. An increase in K _trans after SRS was predictive of tumor progression (hazard ratio?=?1.50; 95 % CI?=?1.16–1.70, p?<?0.001). An increase of 15 % in K _trans showed a sensitivity of 78 % and a specificity of 85 % for the prediction of progression at midterm follow-up.

Conclusion

SRS was associated with a reduction of K _trans values of the cerebral metastases in the early post-treatment period. Furthermore, K _trans variation as assessed using DCE MRI may be helpful to predict midterm outcomes after SRS.     

Partial splenic embolisation using n-butyl cyanoacrylate: intraprocedural evaluation by magnetic resonance imaging

Objectives

To evaluate the use of diffusion-weighted imaging (DWI) for estimating infarcted splenic volume during partial splenic embolisation (PSE) using n-butyl cyanoacrylate (NBCA).

Methods

Twenty consecutive patients (57.2?±?11.7 years) with hypersplenism underwent PSE. Intrasplenic branches were embolised using NBCA via a 2.1-French microcatheter aiming at infarction of 50 to 80 % of total splenic volume. Immediately after PSE, signal intensities (SI) of embolised and non-embolised splenic parenchyma were measured on DWI. Semi-automated volumetry (SAV) on DWI was compared with conventional manual volumetry (MV) on contrast-enhanced CT 1 week after PSE. Platelet counts were recorded before and after PSE.

Results

The SI on DWI in the embolised parenchyma decreased significantly (P?<?0.01) to 24.7?±?8.1 % as compared to non-embolised parenchyma. SAV and MV showed a strong correlation (r?=?0.913 before PSE, r?=?0.935 after PSE, P?<?0.01) and significant (P?<?0.01) reduction of normal splenic volume was demonstrated on both SAV (71.9?±?12.4 %) and MV (73.6?±?9.3 %) after PSE. Based on the initial SAV, three patients (15 %) underwent additional branch embolisation to reach sufficient infarction volume. Platelet counts elevated significantly (522.8?±?209.1 %, P?<?0.01) by 2 weeks after PSE. No serious complication was observed.

Conclusion

Immediate SI changes on DWI after PSE allowed semi-automated splenic volumetry on site.

Key Points

? Partial splenic embolisation (PSE) is an important interventional technique for hypersplenism ? Diffusion-weighted MR reveals an immediate decrease in signal in the embolised parenchyma ? Such signal reduction permits semi-automated splenic volumetry on site. ? This allows precise quantification of the amount of parenchyma infarcted, avoiding additional PSE.     

Optimal table feed in run-off CT angiography in patients with abdominal aortic aneurysms

Objectives

To assess the influence of different table feeds (TFs) on vascular enhancement and image quality in patients with an abdominal aortic aneurysm (AAA) undergoing computed tomography (CT) angiography of the lower extremities (run-off CTA).

Methods

Seventy-nine patients (71?±?8 years) with an AAA (>30 mm) who underwent run-off CTA between January 2004 and August 2011 were included in this retrospective institutional review board-approved study. Run-off CTA was conducted using 16- and 64-row CT. The range of TFs was 30–86 mm/s and was categorised in quartiles TF1 (32.6?±?1.9 mm/s), TF2 (38.9?±?0.9 mm/s), TF3 (43.9?±?3.1 mm/s) and TF4 (57.4?±?10.5 mm/s). Image quality was rated independently by two radiologists and vessel enhancement was assessed.

Results

Image quality was diagnostic at all aortic, pelvic and almost all thigh levels. Below the knee, the number of diagnostic levels was highest for TF1 and decreased to TF4. Arterial enhancement between the aorta and fibular trunk was not different in all TF groups, P?>?0.05. At the calf and foot strongest arterial enhancement was noted for TF1 and TF2 and decreased to TF4, P?<?0.01.

Conclusion

Results indicate that the highest image quality of run-off CTA in patients with an AAA may be obtained using table feeds measuring 30–35 mm/s.

Key Points

? CTA has become a key investigation for peripheral vascular disease. ? Run-off CTA is more complex in patients with an abdominal aortic aneurysm. ? Run-off CTA is feasible with a short bolus of intravenous contrast medium. ? A constant 30–35 mm/s table feed provides the highest likelihood of diagnostic images.