Augmented reality visualisation using an image overlay system for MR-guided interventions: technical performance of spine injection procedures in human cadavers at 1.5 Tesla

Objectives

To prospectively assess the technical performance of an augmented reality system for MR-guided spinal injection procedures.

Methods

The augmented reality system was used with a clinical 1.5-T MRI system. A total of 187 lumbosacral spinal injection procedures (epidural injection, spinal nerve root injection, facet joint injection, medial branch block, discography) were performed in 12 human cadavers. Needle paths were planned with the Perk Station module of 3D Slicer software on high-resolution MR images. Needles were placed under augmented reality MRI navigation. MRI was used to confirm needle locations. T1-weighted fat-suppressed MRI was used to visualise the injectant. Outcome variables assessed were needle adjustment rate, inadvertent puncture of non-targeted structures, successful injection rate and procedure time.

Results

Needle access was achieved in 176/187 (94.1 %) targets, whereas 11/187 (5.9 %) were inaccessible. Six of 11 (54.5 %) L5–S1 disks were inaccessible, because of an axial obliquity of 30? (27?–34?); 5/11 (45.5 %) facet joints were inaccessible because of osteoarthritis or fusion. All accessible targets (176/187, 94.1 %) were successfully injected, requiring 47/176 (26.7 %) needle adjustments. There were no inadvertent punctures of vulnerable structures. Median procedure time was 10.2 min (5–19 min).

Conclusions

Image overlay navigated MR-guided spinal injections were technically accurate. Disks with an obliquity ≥27? may be inaccessible.

Key Points

? Augmented reality technology facilitates MR-guided spine injections. ? Patient and operator exposure to ionising radiation can be obviated. ? MR imaging guidance enabled the procedure without need of a dedicated interventional MRI system. ? Various MR-guided spine injection procedures using augmented reality are technically accurate. ? Augmented reality has potential to simplify the workflow of MR-guided spine injections.     

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 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 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.     

MR-guided microwave ablation in hepatic tumours: initial results in clinical routine

Objectives

Evaluation of the technical success, patient safety and technical effectiveness of magnetic resonance (MR)-guided microwave ablation of hepatic malignancies.

Methods

Institutional review board approval and informed patient consent were obtained. Fifteen patients (59.8 years?±?9.5) with 18 hepatic malignancies (7 hepatocellular carcinomas, 11 metastases) underwent MR-guided microwave ablation using a 1.5-T MR system. Mean tumour size was 15.4 mm?±?7.7 (7-37 mm). Technical success and ablation zone diameters were assessed by post-ablative MR imaging. Technique effectiveness was assessed after 1 month. Complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE). Mean follow-up was 5.8 months?±?2.6 (1-10 months).

Results

Technical success and technique effectiveness were achieved in all lesions. Lesions were treated using 2.5?±?1.2 applicator positions. Mean energy and ablation duration per tumour were 37.6 kJ?±?21.7 (9-87 kJ) and 24.7 min?±?11.1 (7-49 min), respectively. Coagulation zone short- and long-axis diameters were 31.5 mm?±?10.5 (16-65 mm) and 52.7 mm?±?15.4 (27-94 mm), respectively. Two CTCAE-2-complications occurred (pneumothorax, pleural effusion). Seven patients developed new tumour manifestations in the untreated liver. Local tumour progression was not observed.

Conclusions

Microwave ablation is feasible under near real-time MR guidance and provides effective treatment of hepatic malignancies in one session.

Key Points

? Planning, applicator placement and therapy monitoring are possible without using contrast enhancement ? Energy transmission from the generator to the scanner room is safely possible ? MR-guided microwave ablation provides effective treatment of hepatic malignancies in one session ? Therapy monitoring is possible without applicator retraction from the ablation site

     

US-Guided Femoral and Sciatic Nerve Blocks for Analgesia During Endovenous Laser Ablation

Purpose

Endovenous laser ablation may be associated with significant pain when performed under standard local tumescent anesthesia. The purpose of this study was to investigate the efficacy of femoral and sciatic nerve blocks for analgesia during endovenous ablation in patients with lower extremity venous insufficiency.

Methods

During a 28-month period, ultrasound-guided femoral or sciatic nerve blocks were performed to provide analgesia during endovenous laser ablation in 506 legs and 307 patients. The femoral block (n = 402) was performed at the level of the inguinal ligament, and the sciatic block at the posterior midthigh (n = 124), by injecting a diluted lidocaine solution under ultrasound guidance. After the blocks, endovenous laser ablations and other treatments (phlebectomy or foam sclerotherapy) were performed in the standard fashion. After the procedures, a visual analogue pain scale (1–10) was used for pain assessment.

Results

After the blocks, pain scores were 0 or 1 (no pain) in 240 legs, 2 or 3 (uncomfortable) in 225 legs, and 4 or 5 (annoying) in 41 legs. Patients never experienced any pain higher than score 5. The statistical analysis revealed no significant difference between the pain scores of the right leg versus the left leg (p = 0.321) and between the pain scores after the femoral versus sciatic block (p = 0.7).

Conclusions

Ultrasound-guided femoral and sciatic nerve blocks may provide considerable reduction of pain during endovenous laser and other treatments, such as ambulatory phlebectomy and foam sclerotherapy. They may make these procedures more comfortable for the patient and easier for the operator.     

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     

Sonographically guided anesthetic injection of anterior scalene muscle for investigation of neurogenic thoracic outlet syndrome

Objective

To describe the technique and complications of sonographically guided anesthetic injection of the anterior scalene muscle in patients being investigated for neurogenic thoracic outlet syndrome.

Material and methods

Subjects were identified via a retrospective review of medical records. For the procedure a 25-gauge needle was introduced into the anterior scalene muscle under real-time ultrasound guidance followed by injection of local anesthetic. The procedures were evaluated for technical success, which was defined as satisfactory identification of anterior scalene muscle, intramuscular needle placement, and intramuscular delivery of medication. There was a short-term follow-up to determine procedure-related complications and rate of unintended brachial plexus (BP) block, manifested by upper extremity paresthesias and/or weakness.

Results

Twenty-six subjects with suspected neurogenic thoracic outlet syndrome underwent 29 injections (three subjects received bilateral injections). Technical success was achieved in all procedures. The mean duration of the procedure was 30 min, and there were no cases of intravascular needle placement or neurogenic pain during the injection. No major complications occurred. Temporary symptoms of partial BP block occurred after nine injections (9/29, 31%), and a temporary complete BP block occurred after one injection (1/29, 3%).

Conclusion

Sonographically guided anesthetic injection of the anterior scalene muscle is a safe and well-tolerated diagnostic test for patients being investigated for neurogenic thoracic outlet syndrome.     

High-resolution magnetic resonance-guided posterior femoral cutaneous nerve blocks

Objective

To assess the feasibility, technical success, and effectiveness of high-resolution magnetic resonance (MR)-guided posterior femoral cutaneous nerve (PFCN) blocks.

Materials and methods

A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 patients [6 (75 %) female, 2 (25 %) male; mean age, 47 years; range, 42–84 years] with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed with a clinical wide-bore 1.5-T MR imaging system. High-resolution MR imaging was utilized for visualization and targeting of the PFCN. Commercially available, MR-compatible 20-G needles were used for drug delivery. Variables assessed were technical success (defined as injectant surrounding the targeted PFCN on post-intervention MR images) effectiveness, (defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block), rate of complications, and length of procedure time.

Results

MR-guided PFCN injections were technically successful in 12/12 cases (100 %) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100 %). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30–70) min.

Conclusions

Our initial results demonstrate that this technique of selective MR-guided PFCN blocks is feasible and suggest high technical success and effectiveness. Larger studies are needed to confirm our initial results.     

Threshold-based prediction of the coagulation zone in sequential temperature mapping in MR-guided radiofrequency ablation of liver tumours

Objective

To evaluate different cut-off temperature levels for a threshold-based prediction of the coagulation zone in magnetic resonance (MR)-guided radiofrequency (RF) ablation of liver tumours.

Methods

Temperature-sensitive measurements were acquired during RF ablation of 24 patients with primary (6) and secondary liver lesions (18) using a wide-bore 1.5?T MR sytem and compared with the post-interventional coagulation zone. Temperature measurements using the proton resonance frequency shift method were performed directly subsequent to energy application. The temperature maps were registered on the contrast-enhanced follow-up MR images acquired 4?weeks after treatment. Areas with temperatures above 50°, 55° and 60°C were segmented and compared with the coagulation zones. Sensitivity and positive predictive value were calculated.

Results

No major complications occurred and all tumours were completely treated. No tumour recurrence was observed at the follow-up examination after 4?weeks. Two patients with secondary liver lesions showed local tumour recurrence after 4 and 7?months. The 60°C threshold level achieved the highest positive predictive value (87.7?±?9.9) and the best prediction of the coagulation zone.

Conclusions

For a threshold-based prediction of the coagulation zone, the 60°C cut-off level achieved the best prediction of the coagulation zone among the tested levels.

Key Points

? Temperature monitoring can be used to survey MR-guided radiofrequency ablation ? The developing ablation zone can be estimated based on post-interventional temperature measurements ? A 60°C threshold level can be used to predict the ablation zone ? The 50°C and 55°C temperature zones tend to overestimate the ablation zone     

MR-guided radiofrequency ablation using a wide-bore 1.5-T MR system: clinical results of 213 treated liver lesions

Objective

To evaluate the technical effectiveness, technical success and patient safety of MR-guided radiofrequency (RF) ablation of liver malignancies using a wide-bore 1.5-T MR system.

Methods

In 110 patients, 56 primary liver lesions and 157 liver metastases were treated in 157 sessions using percutaneous RF ablation. Mean lesion diameter was 20?mm (range 4–54?mm). All planning, procedural and post-interventional control MR investigations were carried out using a wide-bore 1.5-T MR system. Technical success was assessed by a contrast-enhanced MR liver examination immediately after the intervention. Technique effectiveness was assessed by dynamic hepatic MR study 1?month post ablation; mean follow-up period was 24.2?months (range 5–44).

Results

Technical success and technique effectiveness were achieved in 210/213 lesions (98.6?%). In 18/210 lesions (8.6?%), local tumour progression occurred 4–28?months after therapy. Seven of these 18 lesions were treated in a second session achieving complete ablation, 6 other lesions were referred to surgery. Overall RF effectiveness rate was 199/213 (93.4?%); overall therapy success (including surgery) was 205/213 (96.2?%). Two major complications (1.3?%) (bleeding and infected biloma) and 14 (8.9?%) minor complications occurred subsequent to 157 interventions.

Conclusion

Wide-bore MR-guided RF ablation is a safe and effective treatment option for liver lesions.

Key Points

? Magnetic resonance-guided radiofrequency ablation offers various options for monitoring therapy. ? All steps of RF ablation carried out in 1.5-T wide-bore system. ? Therapeutic decisions were based on T1-weighted imaging. ? Technical success and technical effectiveness were high. ? Local tumour progression rate was 8.6?% over a 24-month mean follow-up.     

Volumetric MR-guided high-intensity focused ultrasound ablation of uterine fibroids: treatment speed and factors influencing speed

Objectives

To assess the treatment speed of volumetric magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of symptomatic uterine fibroids, with a focus on factors affecting treatment speed.

Methods

We received Institutional Review Board approval, and informed consent was obtained from all participants. Among 109 patients referred, 43 women (39.4 %) (mean age, 43.7 years), with 112 fibroids passed the screening. We treated 53 symptomatic uterine fibroids (47.3 %, 53/112) (volume, 341.2?±?256.5 ml) using volumetric MR-HIFU ablation. We assessed procedure times, non-perfused volume (NPV) and treatment speed (NPV/treatment time). We statistically analysed the factors affecting treatment speed using multiple logistic regression tests.

Results

Technical success was achieved in 42 of 43 cases. MR room time (from entrance to exit) and treatment time (from first to last sonication) were 216.0?±?40.6 min and 131.5?±?55.9 min, respectively. Immediate NPV was 178.9?±?147.3 ml, which was 57.4?±?25.5 % of the fibroid volume. Treatment speed was 81.8?±?48.0 ml/h. Multivariate analysis showed that a large fibroid volume (P?<?0.001), a low signal intensity ratio of fibroid to skeletal muscle on T2-weighted images (P?=?0.009) and timing after completion of the learning curve (P?<?0.001) significantly increased treatment speed.

Conclusion

Volumetric MR-HIFU ablation can effectively treat symptomatic uterine fibroids. The treatment speed appeared to improve when treating large and/or dark fibroids as well as upon completion of the learning curve.

Key Points

? High-intensity focused ultrasound (HIFU) offers another interventional radiological option for treating fibroids ? Volumetric MR-guided HIFU ablation can treat uterine fibroids in a timely fashion ? Treatment speed appeared to improve when treating large and/or dark fibroids ? Treatment speed appeared to improve upon completion of the learning curve     

MR arthrography of the shoulder: tolerance evaluation of four different injection techniques

Objective

We sought to prospectively evaluate patients?? pain perception and technical success of four different arthrographic techniques for shoulder MR arthrography.

Materials and methods

A total of 125 consecutive patients were referred for shoulder MR arthrography. The patients were randomly injected under fluoroscopic guidance (n ₁ ?=?37), with CT guidance using an anterior (n ₂ ?=?29) or a posterior approach (n ₃ ?=?32) and with ultrasound guidance (n ₄ ?=?27). For each patient, absolute periprocedural pain on a numerical rating pain scale (0?=???no pain??, 10?=???intolerable pain??), technical success of the method used, and reason for referral were recorded.

Results

The technical success rate was 100?% for all injection methods. The results regarding absolute periprocedural pain were as follows: fluoroscopic guidance showed a mean pain of 4.05?±?1.24, CT anterior guidance demonstrated a mean pain of 3.87?±?0.95, CT posterior guidance showed a mean pain of 1.59?±?0.81, and ultrasound guidance a mean pain of 3.63?±?1.12. A significant difference (p?<?.05) was observed for the posterior route under CT guidance. The mean pain level was significantly higher for older (> 51?year) female patients.

Conclusions

No differences were found for the technical success rate of the aforementioned techniques. A CT-guided posterior approach seems to be a more comfortable method for the patient.     

MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open high-field MRI scanner with respiratory gating

Objectives

To prospectively evaluate the feasibility, safety and accuracy of MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open MR scanner with respiratory gating.

Methods

Sixty-five patients with 65 solitary pulmonary lesions underwent MR-guided percutaneous coaxial cutting needle biopsy using a 1.0-T open MR scanner with respiratory gating. Lesions were divided into two groups according to maximum lesion diameters: ≤2.0 cm (n?=?31) and >2.0 cm (n?=?34). The final diagnosis was established in surgery and subsequent histology. Diagnostic accuracy, sensitivity and specificity were compared between the groups using Fisher’s exact test.

Results

Accuracy, sensitivity and specificity of MRI-guided percutaneous pulmonary biopsy in diagnosing malignancy were 96.9 %, 96.4 % and 100 %, respectively. Accuracy, sensitivity and specificity were 96.8 %, 96.3 % and 100 % for lesions 2.0 cm or smaller and 97.1 %, 96.4 % and 100 %, respectively, for lesions larger than 2.0 cm. There was no significant difference between the two groups (P?>?0.05). Biopsy-induced complications encountered were pneumothorax in 12.3 % (8/65) and haemoptysis in 4.6 % (3/65). There were no serious complications.

Conclusions

MRI-guided percutaneous biopsy using a 1.0-T open MR scanner with respiratory gating is an accurate and safe diagnostic technique in evaluation of pulmonary lesions.

Key Points

? MRI-guided percutaneous lung biopsy using a 1.0-T open MR scanner is feasibility. ? 96.9 % differentiation accuracy of malignant and benign lung lesions is possible. ? No serious complications occurred in MRI-guided lung biopsy.

     

Volumetric feedback ablation of uterine fibroids using magnetic resonance-guided high intensity focused ultrasound therapy

Objective

The purpose of this prospective multicenter study was to assess the safety and technical feasibility of volumetric Magnetic Resonance-guided High Intensity Focused Ultrasound (MR-HIFU) ablation for treatment of patients with symptomatic uterine fibroids.

Methods

Thirty-three patients with 36 fibroids were treated with volumetric MR-HIFU ablation. Treatment capability and technical feasibility were assessed by comparison of the Non-Perfused Volumes (NPVs) with MR thermal dose predicted treatment volumes. Safety was determined by evaluation of complications or adverse events and unintended lesions. Secondary endpoints were pain and discomfort scores, recovery time and length of hospital stay.

Results

The mean NPV calculated as a percentage of the total fibroid volume was 21.7%. Correlation between the predicted treatment volumes and NPVs was found to be very strong, with a correlation coefficient r of 0.87. All patients tolerated the treatment well and were treated on an outpatient basis. No serious adverse events were reported and recovery time to normal activities was 2.3?±?1.8?days.

Conclusion

This prospective multicenter study proved that volumetric MR-HIFU is safe and technically feasible for the treatment of symptomatic uterine fibroids.

Key Points

? Magnetic-resonance-guided high intensity focused ultrasound allows non-invasive treatment of uterine fibroids. ? Volumetric feedback ablation is a novel technology that allows larger treatment volumes ? MR-guided ultrasound ablation of uterine fibroids appears safe using volumetric feedback     

Inferior Pancreaticoduodenal Artery Aneurysms Associated with Occlusive Lesions of the Celiac Axis: Diagnosis, Treatment Options, Outcomes, and Review of the Literature

Purpose

To describe the presentation, treatment, and outcomes for 14 patients with aneurysms of the inferior pancreaticoduodenal arteries associated with occlusive lesions of the celiac axis, and to review the literature for similar cases.

Methods

Over a period of 12 years, 14 patients (10 women and 4 men) ranging in age from 26 to 50 (mean 46) years were demonstrated to have aneurysms of the inferior pancreaticoduodenal artery origin associated with stenosis or occlusion of the celiac axis. All patients were treated by a combination of surgery and interventional radiology.

Results

Outcome data collected between 3 months and 4 years (mean 2 years) demonstrated that all aneurysms remained excluded, and all 14 patients were well. The 49 case reports in the literature confirm the findings of this cohort.

Conclusion

In inferior pancreaticoduodenal artery aneurysm resulting from celiac occlusive disease, endovascular treatment is best achieved by stenting the celiac axis and/or embolizing the aneurysm when necessary.     

Driven Around the Bend: Novel Use of a Curved Steerable Needle

Purpose

This technical note describes the novel use of a curved, steerable needle to access symptomatic osseous lesions in the pelvis and sacrum for palliative percutaneous treatment that would otherwise be difficult to treat using conventional straight needles.

Materials and Methods

Seven patients with lytic bone lesions were treated. One patient had multiple myeloma; the remaining had metastatic disease: breast carcinoma (n = 2), colorectal carcinoma (n = 1), renal cell carcinoma (n = 1), squamous cell carcinoma (n = 1), and leiomyosarcoma (n = 1). Five of the seven patients had lesions in the posterior acetabulum, and the two other patients had lesions in the sacrum. Four of the seven patients received radiofrequency ablation followed by cementoplasty; three patients received cementation alone. We used a novel needle designed for vertebroplasty, which has an articulating tip allowing it to be guided into lytic bone lesions located in difficult-to-access regions of the pelvis and sacrum.

Results

All patients were successfully treated with cementoplasty either with or without thermal ablation. No serious adverse events were reported. The needle was difficult to withdraw in two patients.

Conclusion

Steerable curved needles can be successfully used to treat lytic osseous metastases with cementoplasty when lesions are located in sites that may be difficult to reach using conventional straight needles.     

Prospective evaluation of magnetic resonance enterography for the detection of mesenteric small bowel tumours

Purpose

To prospectively evaluate magnetic resonance (MR) enterography for detecting mesenteric small-bowel tumours (MSBTs) and assess the added value of gadolinium-chelate injection.

Material and methods

Over a 2-year period MR enterography examinations of 75 patients (33 men, 42 women; mean age, 53.8 years; range, 19–85) with suspected MSBT were blindly analysed by two readers for the presence of MSBT. Sensitivities, specificities, predictive positive values (PPVs), negative predictive values (NPVs) and accuracies of MR enterography for the detection of MSBT were calculated on per-patient and per-lesion bases. The McNemar test was used to compare sensitivities and specificities of the unenhanced and gadolinium-enhanced sets of MR enterographies.

Results

Thirty-seven MSBTs were pathologically confirmed in 26 patients. The mean tolerance score of the examinations was 0.7. On a per-patient basis, sensitivity, specificity, PPV, NPV and accuracy for detection of MSBT were 96 % [95 % CI, 89–100 %], 96 % [90–100 %], 93 % [83–100 %], 98 % [94–100 %] and 96 % [92–100 %], respectively. On a per-lesion basis, sensitivity and PPV were 70 % [56–85 %] and 93 % [83–100 %], respectively. Gadolinium injection yielded higher sensitivities on both bases (P?=?0.008).

Conclusion

MR enterography is an accurate and well-tolerated imaging modality for detecting MSBT. Intravenous administration of gadolinium-chelate improves sensitivity for MSBT detection.

Key Points

? MR enterography accurately detects mesenteric small bowel tumours. ? MR enterography is a well-tolerated imaging technique. ? Intravenous administration of gadolinium chelate improves sensitivity for detecting small-bowel tumours.     

Feasibility Study of Needle Placement in Percutaneous Vertebroplasty: Cone-Beam Computed Tomography Guidance Versus Conventional Fluoroscopy

Objective

To investigate the accuracy, procedure time, fluoroscopy time, and dose area product (DAP) of needle placement during percutaneous vertebroplasty (PVP) using cone-beam computed tomography (CBCT) guidance versus fluoroscopy.

Materials and Methods

On 4 spine phantoms with 11 vertebrae (Th7–L5), 4 interventional radiologists (2 experienced with CBCT guidance and two inexperienced) punctured all vertebrae in a bipedicular fashion. Each side was randomization to either CBCT guidance or fluoroscopy. CBCT guidance is a sophisticated needle guidance technique using CBCT, navigation software, and real-time fluoroscopy. The placement of the needle had to be to a specific target point. After the procedure, CBCT was performed to determine the accuracy, procedure time, fluoroscopy time, and DAP. Analysis of the difference between methods and experience level was performed.

Results

Mean accuracy using CBCT guidance (2.61 mm) was significantly better compared with fluoroscopy (5.86 mm) (p < 0.0001). Procedure time was in favor of fluoroscopy (7.39 vs. 10.13 min; p = 0.001). Fluoroscopy time during CBCT guidance was lower, but this difference is not significant (71.3 vs. 95.8 s; p = 0.056). DAP values for CBCT guidance and fluoroscopy were 514 and 174 mGy cm², respectively (p < 0.0001). There was a significant difference in favor of experienced CBCT guidance users regarding accuracy for both methods, procedure time of CBCT guidance, and added DAP values for fluoroscopy.

Conclusion

CBCT guidance allows users to perform PVP more accurately at the cost of higher patient dose and longer procedure time. Because procedural complications (e.g., cement leakage) are related to the accuracy of the needle placement, improvements in accuracy are clinically relevant. Training in CBCT guidance is essential to achieve greater accuracy and decrease procedure time/dose values.     

Influence of Calcium on Choline Measurements by 1H MR Spectroscopy of Thigh Muscles

Objective

To study the effects of calcium on the choline peak measurements with 1H MR spectroscopy.

Material and methods

The thigh muscles of two cadaveric specimens were prospectively evaluated on a 3 T MR unit before and after the injection of calcium carbonate (up to 0.4322 g). The choline peaks of 147 spectra from 10 different anatomic locations were quantitatively evaluated. The influence of the calcium concentration and its disposition with respect to the main magnetic field were considered. B₀ phase maps were used to evaluate field inhomogeneities.

Results

The presence of calcium led to a 43 % underestimation of the choline peak and the choline concentration (p?=?0.0002 and 0.0036). The mean choline concentrations before and after CaCO3 injection were 3.53?±?1.72 mmol/l and 1.58?±?0.63 mmol/l. The influence of calcium carbonate on the choline peak estimations was proportional to the calcium concentration. There was a significant position-dependent difference in the estimation of the choline peak amplitude (p?<?0.0154). Calcium injection led to a measurable increase in field inhomogeneities.

Conclusion

There was a significant underestimation of the choline peak amplitude and concentration in the presence of calcium, which might cause misinterpretations of MR spectra.

Key Points

? The presence of calcium led to significant underestimation of choline measurements. ? The influence of calcium is dependent on its concentration and distribution. ? Quantitative MR spectroscopy of calcified tumours should be interpreted with caution.