MR-guided facet joint injection therapy using an open 1.0-T MRI system: an outcome study

Objectives

To evaluate the accuracy, safety and efficacy of magnetic resonance imaging (MRI)-guided facet joint injection therapy using a 1.0-T open MRI.

Methods

One hundred and sixty-six facet joint blocks in 45 patients with lower back pain were performed under MR fluoroscopic guidance using a proton-density-weighted turbo-spin-echo sequence. An in-room monitor, wireless MR-mouse for operator-controlled multiplanar navigation, a flexible surface coil and MR-compatible 20-G needle were used. Clinical outcome was evaluated by questionnaire before intervention and after 1 week, 3, 6 and 12 months using a numerical visual analogue scale (VAS).

Results

All facet joint blocks were considered technically successful with distribution of the injectant within and/or around the targeted facet joint. No major complications occurred. The final outcome analysis included 38 patients. An immediate effect was reported by 63 % of the patients. A positive mid-/long-term effect was seen in 13 patients (34 %) after 6 months and in 9 patients (24 %) after 12 months. Mean VAS was reduced from 7.1?±?1.7 (baseline) to 3.5?±?2.2, 4.1?±?3.0, 3.8?±?2.9 and 4.6?±?2.9 at 1 week, 3, 6 and 12 months (P?<?0.01).

Conclusions

MR-guided facet joint injection therapy of the lumbosacral spine is accurate, safe and efficient in the symptomatic treatment of lower back pain.

Key Points

? MR-guided facet joint infiltration provides an alternative to CT and conventional fluoroscopy. ? Clinical outcomes are comparable with conventional fluoroscopy and CT-guided facet joint interventions. ? Ionising radiation can be avoided for both patient and physician. ? MR-guided facet joint injection provides safe and effective treatment of back pain.     

MR-guided Neurolytic Celiac Plexus Ablation: An Evaluation of Effect and Injection Spread Pattern in Cancer Patients with Celiac Tumor Infiltration

Objective

The purpose of this study was to evaluate the feasibility, the initial accuracy, and the effects of the MR-guided neurolytic celiac plexus ablation as a method to treat cancer-induced chronic abdominal pain.

Methods

Thirteen celiac plexus ablations were performed for 12 patients. A 0.23-T open MRI scanner with optical navigation was used for procedural guidance. As an adjunct to the MR-guided needle positioning, the needle location was confirmed with saline injection and consequent MR imaging (STIR sequence). The spread of the ablative injection material (alcohol-lidocaine mix) was observed by repeating this sequence after the therapeutic injection. Pain scores from seven patients (eight ablations) were used to assess the therapy effect.

Results

MR guidance allowed adequate needle positioning and visualization of injection material in all cases. The rest pain scores significantly decreased from 4 (median) at baseline to 1 (median) at 2 weeks (p < 0.05). Average and worst pain experienced during the past week were significantly lower at the 2-week time point compared with the baseline (p < 0.05). However, the intervention did not result in reduction of opioid use at 2 weeks.

Conclusions

MR guidance is an accurate and safe method for celiac plexus ablation with positive therapeutic effect.     

Cost comparison of nerve root infiltration of the lumbar spine under MRI and CT guidance

Objectives

To compare the costs of CT- and MR-guided lumbosacral nerve root infiltration for minimally invasive treatment of low back pain and radicular pain.

Methods

Ninety patients (54 men, 36 women; mean age, 45.5?±?12.8 years) underwent MR-guided single-site periradicular lumbosacral nerve root infiltration with 40 mg of triamcinolone acetonide. A further 91 patients (48 men, 43 women; mean age, 59.1?±?13.8 years) were treated under CT fluoroscopy guidance. Prorated costs of equipment use (purchase, depreciation and maintenance), staff costs based on involvement times and expenditure for disposables were identified for MR- and CT-guided procedures.

Results

Mean intervention time was 20.6 min (14–30 min) for MR-guided and 14.3 min (7–32 min) for CT-guided treatment. The average total costs per patient were €177 for MR-guided and €88 for CT-guided interventions. These consisted of (MR/CT guidance) €93/29 for equipment use, €43/35 for staff and €41/24 for disposables.

Conclusions

Lumbosacral nerve root infiltration using MRI guidance is still about twice as expensive as infiltration using CT guidance. Given the advantages of no radiation exposure and possible future decrease in prices for MRI devices and MR-compatible injection needles, MR-guided nerve root infiltration may become a promising alternative to the CT-guided procedure.

Key Points

? MR-guided nerve root infiltration therapy is now technically and clinically established. ? Costs using MRI guidance are still about double those for CT guidance. ? MR guidance involves no radiation exposure to patients and personnel. ? MR-guided nerve root infiltration may become a promising alternative to CT.     

MR-Guided Vertebroplasty With Augmented Reality Image Overlay Navigation

Purpose

To evaluate the feasibility of magnetic resonance imaging (MRI)-guided vertebroplasty at 1.5 Tesla using augmented reality image overlay navigation.

Materials and Methods

Twenty-five unilateral vertebroplasties [5 of 25 (20 %) thoracic, 20 of 25 (80 %) lumbar] were prospectively planned in 5 human cadavers. A clinical 1.5-Teslan MRI system was used. An augmented reality image overlay navigation system and 3D Slicer visualization software were used for MRI display, planning, and needle navigation. Intermittent MRI was used to monitor placement of the MRI-compatible vertebroplasty needle. Cement injections (3 ml of polymethylmethacrylate) were performed outside the bore. The cement deposits were assessed on intermediate-weighted MR images. Outcome variables included type of vertebral body access, number of required intermittent MRI control steps, location of final needle tip position, cement deposit location, and vertebroplasty time.

Results

All planned procedures (25 of 25, 100 %) were performed. Sixteen of 25 (64 %) transpedicular and 9 of 25 (36 %) parapedicular access routes were used. Six (range 3–9) MRI control steps were required for needle placement. No inadvertent punctures were visualized. Final needle tip position and cement location were adequate in all cases (25 of 25, 100 %) with a target error of the final needle tip position of 6.1 ± 1.9 mm (range 0.3–8.7 mm) and a distance between the planned needle tip position and the center of the cement deposit of 4.3 mm (range 0.8–6.8 mm). Time requirement for one level was 16 (range 11–21) min.

Conclusion

MRI-guided vertebroplasty using image overlay navigation is feasible allowing for accurate vertebral body access and cement deposition in cadaveric thoracic and lumbar vertebral bodies.     

MRI-only lesions: application of diffusion-weighted imaging obviates unnecessary MR-guided breast biopsies

Objective

To assess if the application of diffusion-weighted imaging (DWI) obviates unnecessary MR-guided biopsies in suspicious breast lesions visible only on contrast-enhanced MRI (CE-MRI).

Methods

This institutional review board (IRB)-approved, retrospective, single-centre study included 101 patients (mean age, 49.5; SD 13.9 years) who underwent additional DWI at 1.5 T prior to MRI-guided biopsy of 104 lesions classified as suspicious for malignancy and visible on CE-MRI only. An experienced radiologist, blinded to histopathologic and follow-up results, measured apparent diffusion coefficient (ADC) values obtained from DWI. Diagnostic accuracy was investigated using receiver operating characteristics (ROC) analysis.

Results

Histopathology revealed 20 malignant and 84 benign lesions. Lesions were masses in 61 (15 malignant, 24.6 %) and non-masses in 43 cases (five malignant, 11.6 %). Mean ADC values were 1.53?±?0.38?×?10^?3 mm²/s in benign lesions and 1.06?±?0.27?×?10^?3 mm²/s in malignant lesions. ROC analysis revealed exclusively benign lesions if ADC values were greater than 1.58?×?10^?3 mm²/s. As a consequence, 29 false-positive biopsies (34.5 %) could have been avoided without any false-negative findings. Both in mass and in non-mass lesions, rule-in and rule-out criteria were identified using flexible ADC thresholds based on ROC analysis.

Conclusion

Additional application of DWI in breast lesions visible only on MRI can avoid false-positive, MR-guided biopsies. Thus, DWI should be an integral part of breast MRI protocols.

Key Points

? DWI measurements are a fast and helpful technique for improved breast lesion diagnosis ? DWI application in breast lesions visible only on MRI obviates false-positive, MR-guided biopsies ? Flexible ADC thresholds provide rule-in and rule-out criteria for breast lesion malignancy     

Occurrence of coring after needle insertion through a rubber stopper: study with prednisolone acetate

Objectives

To evaluate the occurrence of coring after needle insertion through the rubber stopper of prednisolone acetate vials.

Methods

Two-hundred vials of prednisolone acetate were randomly distributed to two radiologists. Prednisolone acetate was drawn up through the rubber bung of the vials with an 18-gauge cutting bevelled needle and aspirated with a 5-ml syringe. The presence of coring was noted visually. We systematically put each core in a syringe refilled with 3 ml prednisolone acetate, and injected the medication through a 20-gauge spine needle. Computed tomography was performed to measure the size of each coring.

Results

Coring occurred in 21 out of 200 samples (10.5 %), and was visually detected in the syringe filled up with prednisolone in 11 of the 21 cases. Ten more occult cores were detected only after the syringes and needles were taken apart and rinsed. The core size ranged from 0.6 to 1.1 mm, and 1 of the 21 (4.7 %) cores was ejected through the 20-gauge needle.

Conclusion

Coring can occur after the insertion of a needle through the rubber stopper of a vial of prednisolone acetate, and the resultant core can then be aspirated into the syringe.

Key Points

? Coring occurs after needle insertion through rubber stoppers of prednisolone acetate vials ? Cores within a syringe filled with prednisolone acetate may be undetected ? The frequency of coring during the administration of prednisolone acetate is underestimated     

MRI-guided percutaneous coaxial cutting needle biopsy of small pulmonary nodules: feasibility

Objectives

To prospectively evaluate the feasibility, safety and accuracy of magnetic resonance imaging (MRI)-guided percutaneous coaxial cutting needle biopsy of small (≤2.0 cm in diameter) pulmonary nodules.

Methods

Ninety-six patients (56 men and 40 women) with 96 small lung nodules underwent MRI-guided percutaneous coaxial cutting needle biopsy. These lesions were divided into two groups according to maximum nodule diameters: 0.5–1.0 cm (n?=?25) and 1.1–2.0 cm (n?=?71). The diagnostic accuracy, sensitivity and specificity were calculated, and comparison of the two groups was performed using Fisher's exact test.

Results

All specimens obtained were sufficient for diagnosis. Histological examination of needle biopsy revealed 64 malignant, 30 benign and 2 indeterminate nodules. The final diagnoses from surgery or clinical follow-up were 67 malignant nodules and 29 benign nodules. The diagnostic performance of MRI-guided percutaneous coaxial cutting needle biopsy in diagnosing malignant tumours was as follows: accuracy, 97 %; sensitivity, 96 %; specificity, 100 %; positive predictive value, 100 %; and negative predictive value, 91 %. There was no significant difference between the two groups (P?>?0.05, Fisher's exact test). No serious complications occurred.

Conclusions

MRI-guided percutaneous coaxial cutting needle biopsy is a safe and accurate diagnostic technique in the evaluation of small lung nodules.

Key Points

? MRI-guided biopsy helps clinicians to assess patients with small lung nodules. ? Differentiation of malignant and benign nodules is possible with 97?% accuracy. ? MRI guidance enables accurate lung biopsy without ionising radiation. ? No serious complications occurred in MRI-guided lung biopsy.     

High-resolution MRI predicts steroid injection response in carpal tunnel syndrome patients

Objectives

To correlate median nerve T2 signal and shape at the carpal tunnel with steroid injection (SI) response in carpal tunnel syndrome (CTS) patients.

Methods

One hundred and sixty-three CTS wrists of 92 consecutive patients who were scheduled to undergo SI were prospectively evaluated with 3-T magnetic resonance imaging (MRI) and a nerve conduction study. All patients underwent axial high-resolution T2-weighted MRI (in-plane resolution of 0.25?×?0.25 mm). The CTS wrists were classified into three groups according to the nerve T2 signal and the flattening ratio at the hook of hamate level: group 1, high and oval; group 2, high and flat; group 3, low and flat. Clinical response to SI was evaluated at 6 months after injection.

Results

One hundred and thirteen of the 163 wrists (69.3 %) responded well to SI. The percentage of improvement was 81.7 % (49/60) in group 1, 69.9 % (51/73) in group 2, and 43.3 % (13/30) in group 3 (P?<?0.01). On stepwise logistic regression analysis high-resolution MRI was the only significant independent factor for SI response in CTS patients (P?<?0.01).

Conclusions

High-resolution MRI correlates well with SI response in CTS patients and seems useful for predicting SI response.

Key Points

? MRI may help determine appropriate care in carpal tunnel syndrome. ? MRI helps in therapeutic decision-making whenever steroid injection is considered. ? T2 signal decrease of the median nerve correlates with poor outcome. ? T2 signal decrease of median nerve may reflect fibrosis and amyloid deposition.     

Combined radiofrequency ablation and ethanol injection with a multipronged needle for the treatment of medium and large hepatocellular carcinoma

Objective

To evaluate the efficacy and safety of combined radiofrequency ablation (RFA) and ethanol injection with a multipronged needle in the treatment of medium (3.1–5.0 cm) and large (5.1–7.0 cm) hepatocellular carcinoma (HCC).

Methods

A total of 65 patients with 67 HCC nodules were enrolled in this prospective study. All of them received the treatment of combined RFA and multipronged ethanol injection percutaneously.

Results

The average volume of injected ethanol was 14.4?±?4.1 ml (range, 9–30 ml). The average number of RFA electrode insertions was 1.7?±?0.8 (range, 1–4). The rate of initial local complete response (CR) was 94.0 % (63/67). After additional treatment, technical success was achieved in all HCC nodules. There were no treatment-related deaths, and major complications were observed in 3 (4.6 %) patients. After a mean follow-up of 20.0?±?7.6 months, local tumour progression was observed in 10 (10/67, 14.9 %) tumours, whereas distant recurrence developed in 32 (32/65, 49.2 %) patients. The 1-year and 2-year survival rates were 93.1 % and 88.1 %, respectively.

Conclusion

The combination of RFA and multipronged ethanol injection in the treatment of medium and large HCC is safe and effective with a high rate of local tumour control.

Key Points

? Combined radiofrequency ablation and multipronged ethanol injection is a new therapeutic strategy ? Treatment is safe and effective for medium and large hepatocellular carcinoma (HCC) ? A multipronged needle allows for a homogeneous ethanol distribution     

MR-guided Periarterial Ethanol Injection for Renal Sympathetic Denervation: A Feasibility Study in Pigs

Purpose

To evaluate the feasibility and efficacy of image-guided periarterial ethanol injection as an alternative to transluminal radiofrequency ablation.

Methods

Unilateral renal periarterial ethanol injection was performed under general anesthesia in 6 pigs with the contralateral kidney serving as control. All interventions were performed in an open 1.0 T MRI system under real-time multiplanar guidance. The injected volume was 5 ml (95 % ethanol labelled marked MR contrast medium) in 2 pigs and 10 ml in 4 pigs. Four weeks after treatment, the pigs underwent MRI including MRA and were killed. Norepinephrine (NE) concentration in the renal parenchyma served as a surrogate parameter to analyze the efficacy of sympathetic denervation. In addition, the renal artery and sympathetic nerves were examined histologically to identify evidence of vascular and neural injury.

Results

In pigs treated with 10 ml ethanol, treatment resulted in neural degeneration. We found a significant reduction of NE concentration in the kidney parenchyma of 53 % (p < 0.02) compared with the untreated contralateral kidney. In pigs treated with 5 ml ethanol, no significant changes in histology or NE were observed. There was no evidence of renal arterial stenosis in MRI, macroscopy or histology in any pig.

Conclusion

MR-guided periarterial ethanol injection was feasible and efficient for renal sympathetic denervation in a swine model. This technique may be a promising alternative to the catheter-based approach in the treatment of resistant arterial hypertension.     

Lumbar facet joint injection: feasibility as an alternative method in high-risk patients

Objective

To evaluate the effectiveness of therapeutic facet joint steroid injections for symptoms caused by lumbar spinal stenosis in patients who are at risk of bleeding.

Methods

We analysed 134 patients who had previously undergone one-level bilateral facet joint steroid injections for lumbar radiculopathy caused by spinal stenosis from January 2011 to December 2012. All patients had a bleeding tendency due to several medical conditions. A retrospective chart review was conducted by one radiologist. Response was measured by using a five-point patient satisfaction scale. Evaluations of the relationship between possible outcome predictors were made using the chi-squared or Fisher’s exact test, as appropriate.

Results

Among the 42 enrolled patients (male/female?=?14/28; mean age, 58 years; range, 41–88 years), 25 patients (59.5 %) were classified to have received effective treatment; in 17 patients treatment was classified as ineffective. Eighteen (72 %) of the 25 patients with mild-to-moderate central canal stenosis had symptom relief, and 7 of the 17 (41.2 %) patients with severe central canal stenosis had symptom relief (P?<?0.05). Other outcome predictors were not statistically significant.

Conclusion

Therapeutic facet joint steroid injection is potentially effective for lumbar radiculopathy caused by spinal stenosis. This could be helpful in patients at risk of bleeding.

Key Points

? Epidural injection of steroids is a conventional treatment for lumbar radiculopathy. ? Facet joint steroid injections showed similar therapeutic effects in lumbar spinal stenosis. ? No serious complications, including bleeding, occurred with facet joint injections. ? Facet joint steroid injection offers an alternative therapy in patients with bleeding risk.     

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.     

Whole-body [18F]FDG PET/MRI vs. PET/CT in the assessment of bone lesions in oncological patients: initial results

Objectives

To compare [¹⁸?F]FDG PET/MRI with PET/CT for the assessment of bone lesions in oncologic patients.

Methods

This prospective study included 67 patients with solid tumours scheduled for PET/CT with [¹⁸?F]FDG who also underwent a whole-body PET/MRI scan. The datasets (PET/CT, PET/MRI) were rated by two readers regarding lesion conspicuity (four-point scale) and diagnostic confidence (five-point scale). Median scores were compared using the Wilcoxon test.

Results

Bone metastases were present in ten patients (15 %), and benign bone lesions in 15 patients (22 %). Bone metastases were predominantly localized in the pelvis (18 lesions, 38 %) and the spine (14 lesions, 29 %). Benign bone lesions were exclusively osteosclerotic and smaller than the metastases (mean size 6 mm vs. 23 mm). While PET/CT allowed identification of 45 of 48 bone metastases (94 %), PET/MRI allowed identification of all bone metastases (100 %). Conspicuity of metastases was high for both modalities with significantly better results using PET/MRI (p?<?0.05). Diagnostic confidence in lesion detection was high for both modalities without a significant difference. In benign lesions, conspicuity and diagnostic confidence were significantly higher with PET/CT (p?<?0.05).

Conclusions

[¹⁸?F]FDG PET/MRI shows high potential for the assessment of bone metastases by offering superior lesion conspicuity when compared to PET/CT. In hypersclerotic, benign bone lesions PET/CT still sets the reference.

Key Points

? PET/MRI and PET/CT are of equal value for the identification of disease-positive patients ? PET/MRI offers higher lesion conspicuity as well as diagnostic confidence ? PET/MRI is an attractive new alternative for the assessment of bone metastases     

Simulated required accuracy of image registration tools for targeting high-grade cancer components with prostate biopsies

Objectives

To estimate the required spatial alignment accuracy for correctly grading 95 % of peripheral zone (PZ) prostate cancers using a system for multiparametric magnetic resonance (MR)-guided ultrasound (US) biopsies.

Methods

PZ prostate tumours were retrospectively annotated on multiparametric MR series using prostatectomy specimens as reference standard. Tumours were grouped based on homogeneous and heterogeneous apparent diffusion coefficient (ADC) values using an automated ADC texture analysis method. The proportion of heterogeneous tumours containing a distinct, high Gleason grade tumour focus yielding low ADC values was determined. Both overall tumour and high-grade focal volumes were calculated. All high-grade target volumes were then used in a simulated US biopsy system with adjustable accuracy to determine the hit rate.

Results

An ADC-determined high-grade tumour focus was found in 63 % of the PZ prostate tumours. The focal volumes were significantly smaller than the total tumour volumes (median volume of 0.3 ml and 1.1 ml respectively). To correctly grade 95 % of the aggressive tumour components the target registration error (TRE) should be smaller than 1.9 mm.

Conclusions

To enable finding the high Gleason grade component in 95 % of PZ prostate tumours with MR-guided US biopsies, a technical registration accuracy of 1.9 mm is required.

Key Points

? MRI can identify foci of prostatic cancer with reduced apparent diffusion coefficients ? Sixty-three per cent of prostatic peripheral zone tumours contain high-grade tumour low ADC foci ? The median volume of such foci is 0.3 ml ? Biopsy targets are significantly smaller than whole tumour volumes ? Simulated registration accuracy is 1.9 mm for correctly grading 95 % of tumours     

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.     

Does obesity preclude lumbar puncture with a standard spinal needle? The use of computed tomography to measure the skin to lumbar subarachnoid space distance in the general hospital population

Objectives

Failed lumbar puncture (LP) is a common indication for referral for radiologically guided LP. This study aims to evaluate what percentage of the hospital population would fail an LP using a standard 9-cm needle because of obesity and a skin to subarachnoid space distance greater than 9 cm.

Methods

Images of 402 consecutive patients undergoing computed tomography of the abdomen and pelvis were reviewed. Skin to subarachnoid space distance was calculated using sagittal images. A survey was conducted among junior hospital doctors to assess their experience of performing lumbar puncture in obese patients.

Results

Four hundred patients were included. Fifty-five patients (13.8 %) had a skin to subarachnoid space distance greater than 9 cm. Intra-abdominal fat, subcutaneous fat and abdominal girth correlated with distance between the skin and subarachnoid space. Among junior doctors, 68.3 % (n?=?41) reported LP failure on an obese patient; 78.4 % (n?=?47) were unaware of the existence of a longer needle and 13.3 % (n?=?8) had experience using a longer needle.

Conclusions

A significant proportion of the hospital population will fail LP with a standard length spinal needle. Selecting a longer needle may be sufficient to successfully complete LP in obese patients.

Key Points

? Lumbar puncture failure commonly leads to referral for an image-guided procedure ? Standard lumbar puncture may fail in 13.8 % of patients due to obesity ? 78.4 % of trainee doctors are unaware of the existence of longer spinal-needles ? Using longer spinal needles may allow successful LP in obese patients     

Magnetic resonance imaging for the clinical management of rectal cancer patients: recommendations from the 2012 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus meeting

Objectives

To develop guidelines describing a standardised approach regarding the acquisition, interpretation and reporting of magnetic resonance imaging (MRI) for clinical staging and restaging of rectal cancer.

Methods

A consensus meeting of 14 abdominal imaging experts from the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) was conducted following the RAND-UCLA Appropriateness Method. Two independent (non-voting) chairs facilitated the meeting. Two hundred and thirty-six items were scored by participants for appropriateness and classified subsequently as appropriate or inappropriate (defined by ≥ 80 % consensus) or uncertain (defined by < 80 % consensus). Items not reaching 80 % consensus were noted.

Results

Consensus was reached for 88 % of items: recommendations regarding hardware, patient preparation, imaging sequences, angulation, criteria for MRI assessment and MRI reporting were constructed from these.

Conclusions

These expert consensus recommendations can be used as clinical guidelines for primary staging and restaging of rectal cancer using MRI.

Key Points

? These guidelines recommend standardised imaging for staging and restaging of rectal cancer. ? The guidelines were constructed through consensus amongst 14 abdominal imaging experts. ? Consensus was reached by in 88 % of 236 items discussed.     

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.

     

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     

MR-guided liver tumor ablation employing open high-field 1.0T MRI for image-guided brachytherapy

Objective

To determine the feasibility and safety of image-guided brachytherapy employing a modified open high-field MR system.

Methods

This is a follow-up study of a development project enabling technologies for interventional use of 1.0T open MRI. Modifications included coils and in-bore visualization, fluoroscopic sequences and user interfaces. We recruited 104 patients with 224 liver malignancies to receive MR-guided brachytherapy. Interventions were performed >20 min after Gd-EOB-DTPA. We recorded interventional parameters including the intervention time (from acquisition of the first scout until the final sequence for brachytherapy treatment planning). Two reviewers assessed MR-fluoroscopic images in comparison to plain CT as used in CT intervention, applying a rating scale of 1–10. Statistical analysis included Friedman and Kendall’s W tests.

Results

We employed freehand puncture with interactive dynamic imaging for navigation. Technical success rate was 218 complete ablations in 224 tumours (97%). The median intervention time was 61 min. We recorded no adverse events related to the use of MRI. No major complications occurred. The rate of minor complications was 4%. Local control at 3 months was 96%. Superiority of MR-fluoroscopic, Gd-EOB-DTPA-enhanced images over plain CT was highly significant (P?<?0.001).

Conclusion

MR-guided brachytherapy employing open high-field MRI is feasible and safe.