High-quality MRI Research Articles

High success rates of sedation-free brain MRI scanning in young children using simple subject preparation protocols with and without a commercial mock scanner–the Diabetes Research in Children Network (DirecNet) experience

The ability to lie still in an MRI scanner is essential for obtaining usable image data. To reduce motion, young children are often sedated, adding significant cost and risk. We assessed the feasibility of using a simple and affordable behavioral desensitization program to yield high-quality brain MRI scans in sedation-free children. 222 children (4-9.9years), 147 with type 1 diabetes and 75 age-matched non-diabetic controls, participated in a multi-site study focused on effects of type 1 diabetes on the developing brain. T1-weighted and diffusion-weighted imaging (DWI) MRI scans were performed. All children underwent behavioral training and practice MRI sessions using either a commercial MRI simulator or an inexpensive mock scanner consisting of a toy tunnel, vibrating mat, and video player to simulate the sounds and feel of the MRI scanner. 205 children (92.3%), mean age 7 ± 1.7years had high-quality T1-W scans and 174 (78.4%) had high-quality diffusion-weighted scans after the first scan session. With a second scan session, success rates were 100% and 92.5% for T1-and diffusion-weighted scans, respectively. Success rates did not differ between children with type 1 diabetes and children without diabetes, or between centers using a commercial MRI scan simulator and those using the inexpensive mock scanner. Behavioral training can lead to a high success rate for obtaining high-quality T1-and diffusion-weighted brain images from a young population without sedation.

Advances in diffusion MRI acquisition and processing in the Human Connectome Project

The Human Connectome Project (HCP) is a collaborative 5-year effort to map human brain connections and their variability in healthy adults. A consortium of HCP investigators will study a population of 1200 healthy adults using multiple imaging modalities, along with extensive behavioral and genetic data. In this overview, we focus on diffusion MRI (dMRI) and the structural connectivity aspect of the project. We present recent advances in acquisition and processing that allow us to obtain very high-quality in-vivo MRI data, whilst enabling scanning of a very large number of subjects. These advances result from 2years of intensive efforts in optimising many aspects of data acquisition and processing during the piloting phase of the project. The data quality and methods described here are representative of the datasets and processing pipelines that will be made freely available to the community at quarterly intervals, beginning in 2013.

Study of a dual-mode array integrated in a multi-element transducer for imaging and therapy of prostate cancer

The development of endocavitary dual-mode probes is essential for the accurate treatment of many deep-seated cancers, which require a high imaging resolution and the capacity to selectively treat focal areas in the region of interest. The MULTIP project is aimed at using state-of-art piezoelectric technologies to design dual-mode ultrasonic probes for cancer-foci treatment and monitoring. In order to allow an efficient surgery planning, the technical study has been accompanied by a volume processing study permitting the design of the ultrasonic imaging/therapy process based on high-resolution–high-quality MRI images. Several prototypes were designed based on a simulation study and implemented: 1) two successive wide-band dual-mode transducer allowing imaging at high-resolution (6MHz) on a wide field of view, and therapy at 3MHz with a good transduction efficiency (48% and 70%); 2) a therapy-only transducer matrix adapted to the desired curvature with a high transduction efficiency (70%). Finally, a registration study of MRI volumes on ultrasound volumes has shown that, because of the texture of the ultrasound images, it is more efficient to search at registering the surfaces of the volumes once they have been segmented in each modality, rather than trying to register the two data volumes directly.

SU-E-J-57: MRI-Linac (MRL) Guided Treatment for Esophageal Cancer.

For radiotherapy, oesophageal cancer is located in a difficult area. Spatial control of the dose distribution is difficult to achieve with current CT-based radiation techniques, as on CT, soft-tissue contrast is too low. Furthermore, the oesophagus moves and organs at risk (e.g. lung, heart, liver, spinal cord) are in close proximity. An 1.5 T MRI-accelerator (MRL) has sufficient soft-tissue tumour visualization possibilities to allow for precise real-time, online, position verification and for dose escalation without organ at riskoverdose. Our research consists of the preparatory work for the first clinical study on the MRL for patients with oesophageal cancer. To improve image quality and reduce the motion artefacts, the benefit of cardiac triggering and breath holds is evaluated on fifteen oesophageal patients. Results show the superb image quality of these MRI sequences. The use of this high quality MRI gives the possibility for non-invasive real-time visualization andtracking of the tumour. We quantify oesophageal tumour motion on cineMRI. The tumour is tracked on sequential mixed T1/T2w images (acquisition time: 60s, temporal resolution: 0.5s, slice thickness: 7mm) of a single coronal and sagittal slice using a Minimum Output Sum of Squared Error (MOSSE) adaptive correlation filter. Tumour registration within the individual images can typically be done at a millisecond time scale. Motion of oesophageal tumours can well be tracked and is highly variable between patients. The greatest mobility is seen in cranio-caudal direction, with amaximum peak-to-peak amplitude of tumour movement of 24.5mm followed by the dorso-ventral and the medio-lateral direction. Movement seems greatest in tumours located in the lower part of the oesophagus. This study shows both the superb image quality for GTV localisation and the possibility for on-line and real time tumour tracking. The study opens thepossibility for tracked radiation delivery with a 1.5T MRI accelerator. Partial funding has been obtained by Elekta and Philips.

Cross-validation of brain structural biomarkers and cognitive aging in a community-based study

Population-based studies face challenges in measuring brain structure relative to cognitive aging. We examined the feasibility of acquiring state-of-the-art brain MRI images at a community hospital, and attempted to cross-validate two independent approaches to image analysis. Participants were 49 older adults (29 cognitively normal and 20 with mild cognitive impairment (MCI)) drawn from an ongoing cohort study, with annual clinical assessments within one month of scan, without overt cerebrovascular disease, and without dementia (Clinical Dementia Rating (CDR) < 1). Brain MRI images, acquired at the local hospital using the Alzheimer's Disease Neuroimaging Initiative protocol, were analyzed using (1) a visual atrophy rating scale and (2) a semi-automated voxel-level morphometric method. Atrophy and volume measures were examined in relation to cognitive classification (any MCI and amnestic MCI vs. normal cognition), CDR (0.5 vs. 0), and presumed etiology. Measures indicating greater atrophy or lesser volume of the hippocampal formation, the medial temporal lobe, and the dilation of the ventricular space were significantly associated with cognitive classification, CDR = 0.5, and presumed neurodegenerative etiology, independent of the image analytic method. Statistically significant correlations were also found between the visual ratings of medial temporal lobe atrophy and the semi-automated ratings of brain structural integrity. High quality MRI data can be acquired and analyzed from older adults in population studies, enhancing their capacity to examine imaging biomarkers in relation to cognitive aging and dementia.

MRI at 12 ± 2 months’ corrected age without sedation

Sir,We read with interest the article by Edwards and Arthurs [1]about the methodological challenges of acquiring high-quality MRI in young children. Although the use of anaes-thesia and sedation is often a possibility, parents are oftenhesitant. Consequently, we have developed a protocol forperforming MRI in infants at 12 ± 2 months corrected age[12.4 months corrected age (range 10 months-14 months)]born prematurely or at term, both with and without intra-uterine growth restriction [2, 3]. The protocol involvesparents, clinicians and nurses. The main steps are: (1) todecrease anxiety in parents through explaining and address-ing questions about the procedure, (2) to habituate parentsand child to the noise of the scanner (parents are providedwith aCD ofthescanner sounds to play athome duringtheirchild’s sleep), and (3) to define a sleep plan according to theneeds, sensitivities and regular bedtime routine of the indi-vidual child. On the day of the scan, morning naps arerestricted and the feeding schedule is adjusted according tothe time of the MRI examination. After reception in thedepartment, a quiet room is provided, close to the scanner,with an infant bed, adjustable lighting, soft music, toys andbooks. The child is fed just before the scan and then carriedsleeping into the scanner by the parents. The order of thepulse sequences is ordered according to noise level to coin-cide with the child’s depth of sleep.We have attempted 237 examinations using this proce-dure with successful outcome in 190 (80%) and concludethat high-quality MRI can be performed without sedation at12 ± 2 months corrected age in infants.

Management of incidental pituitary tumors

Pituitary incidentalomas are common lesions for which neurosurgical referrals may become progressively more frequent, given the increasing application of neuroimaging. The initial evaluation of a patient with radiographic evidence of an incidentaloma should focus on addressing two questions: (1) is the lesion causing neurological symptoms, and (2) is the lesion hormonally active? The answers to these two questions provide a framework for subsequent clinical management. The initial patient assessment should include a detailed history and physical examination, including the bedside assessment of visual fields. High-quality MRI imaging is essential, and formal visual field testing should be obtained in patients where the lesion abuts or compresses the optic apparatus. The initial biochemical workup is intended to assess potential pituitary hypo- or hyperfunction and should include measurement of serum levels of prolactin, insulin-like growth factor type-1, free thyroxine, testosterone, and an assessment of axis hypothalamic–pituitary–adrenal axis function. Additional testing may include serum thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone levels. Neurologically-asymptomatic patients without endocrine dysfunction can be managed with observation at regular intervals, including MRI imaging at 6 months and 1 year and then annually for a period of 3 years. Follow-up biochemical assessment is not necessary in the absence of clinical symptoms or radiographic enlargement of the lesion. After 3 years the follow-up interval may be prolonged, although closer follow-up may be indicated for patients with lesions C1 cm. Most patients who either present with or who subsequently develop neurologic or endocrinologic symptoms should be considered for surgery as the first-line therapy.

Management of incidental pituitary tumors

Pituitary incidentalomas are common lesions for which neurosurgical referrals may become progressively more frequent, given the increasing application of neuroimaging. The initial evaluation of a patient with radiographic evidence of an incidentaloma should focus on addressing two questions: (1) is the lesion causing neurological symptoms, and (2) is the lesion hormonally active? The answers to these two questions provide a framework for subsequent clinical management. The initial patient assessment should include a detailed history and physical examination, including the bedside assessment of visual fields. High-quality MRI imaging is essential, and formal visual field testing should be obtained in patients where the lesion abuts or compresses the optic apparatus. The initial biochemical workup is intended to assess potential pituitary hypo- or hyperfunction and should include measurement of serum levels of prolactin, insulin-like growth factor type-1, free thyroxine, testosterone, and an assessment of axis hypothalamic–pituitary–adrenal axis function. Additional testing may include serum thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone levels. Neurologically-asymptomatic patients without endocrine dysfunction can be managed with observation at regular intervals, including MRI imaging at 6 months and 1 year and then annually for a period of 3 years. Follow-up biochemical assessment is not necessary in the absence of clinical symptoms or radiographic enlargement of the lesion. After 3 years the follow-up interval may be prolonged, although closer follow-up may be indicated for patients with lesions C1 cm. Most patients who either present with or who subsequently develop neurologic or endocrinologic symptoms should be considered for surgery as the first-line therapy.

Contrast ventriculo-cisternography: an auxiliary test for suspected fourth ventricular outlet obstruction

Fourth ventricular outlet obstruction (FVOO) causes obstructive hydrocephalus. Often, despite high-quality MRI sequences, differentiation between FVOO and communicating (absorptive) hydrocephalus is not easy. We describe our initial experience with five children with suspected FVOO that underwent CT ventriculography (CTV) or cisternography (CTC), to assist with this difficult diagnosis. Over 2.5 years, five children with suspected FVOO (5 months-7.5 years old) underwent CTV or CTC. Technical and clinical data were retrospectively collected. Four children had progressive macrocephaly, and one child had progressive ventriculomegaly. On CTV/CTC, four of five children showed communication between the ventricular system and spinal subarachnoid space or prepontine cistern, as evidenced by passage of contrast material. One child had a FVOO and therefore underwent an endoscopic third ventriculostomy, and is since, symptom and shunt free for 2.5 years. CT ventriculography in infants, and CT cisternography in elder children, may assist to differentiate between FVOO and communicating hydrocephalus. The importance of these tests is for children with MRI suggestive of FVOO related hydrocephalus, but with no clear demonstration of the obstruction site. The implication of this differentiation may be for deciding between treatment of hydrocephalus with a ventriculoperitoneal shunt or with an endoscopic third ventriculostomy.

Management of incidental pituitary tumors

Pituitary incidentalomas are common lesions for which neurosurgical referrals may become progressively more frequent, given the increasing application of neuroimaging. The initial evaluation of a patient with radiographic evidence of an incidentaloma should focus on addressing two questions: (1) is the lesion causing neurological symptoms, and (2) is the lesion hormonally active? The answers to these two questions provide a framework for subsequent clinical management. The initial patient assessment should include a detailed history and physical examination, including the bedside assessment of visual fields. High-quality MRI imaging is essential, and formal visual field testing should be obtained in patients where the lesion abuts or compresses the optic apparatus. The initial biochemical workup is intended to assess potential pituitary hypo- or hyperfunction and should include measurement of serum levels of prolactin, insulin-like growth factor type-1, free thyroxine, testosterone, and an assessment of axis hypothalamic–pituitary–adrenal axis function. Additional testing may include serum thyroid-stimulating hormone, follicle-stimulating hormone, and luteinizing hormone levels. Neurologically-asymptomatic patients without endocrine dysfunction can be managed with observation at regular intervals, including MRI imaging at 6 months and 1 year and then annually for a period of 3 years. Follow-up biochemical assessment is not necessary in the absence of clinical symptoms or radiographic enlargement of the lesion. After 3 years the follow-up interval may be prolonged, although closer follow-up may be indicated for patients with lesions ≥1 cm. Most patients who either present with or who subsequently develop neurologic or endocrinologic symptoms should be considered for surgery as the first-line therapy.

Imaging in index finger radial collateral ligament injury: attention to detail really pays…

Radial collateral ligament of the index finger is a rare ligament to rupture. X-ray is generally normal, except for subtle findings of soft tissue swelling and occasionally a small fracture. With continuous advances in imaging, ultrasound and high quality MRI allow clear depiction of small structures including joint capsule and collateral ligaments of even the small joints. This helps in definitive diagnosis and determines the extent of injury, which may affect the treatment options and final outcome. We report a rare case of index finger metacarpo-phalangeal joint radial collateral ligament tear. The subtle X-ray abnormality was chased on ultrasound and the diagnosis was proposed on ultrasound and later confirmed on MRI. We also discuss the imaging findings of this rare entity.

Breast MRI in Community Practice: Equipment and Imaging Techniques at Facilities in the Breast Cancer Surveillance Consortium

MRI is increasingly used for the detection of breast carcinoma. Little is known about breast MRI techniques among community practice facilities. The aim of this study was to evaluate equipment and acquisition techniques used by community facilities across the United States, including compliance with minimum standards by the ACRIN® 6667 Trial and the European Society of Breast Imaging. Breast Cancer Surveillance Consortium facilities performing breast MRI were identified and queried by survey regarding breast MRI equipment and technical parameters. Variables included scanner field strength, coil type, acquisition coverage, slice thickness, and the timing of the initial postcontrast sequence. Results were tallied and percentages of facilities meeting ACRIN® and European Society of Breast Imaging standards were calculated. From 23 facilities performing breast MRI, results were obtained from 14 (61%) facilities with 16 MRI scanners reporting 18 imaging parameters. Compliance with equipment recommendations of ≥1.5-T field strength was 94% and of a dedicated breast coil was 100%. Eighty-three percent of acquisitions used bilateral postcontrast techniques, and 78% used slice thickness≤3 mm. The timing of initial postcontrast sequences ranged from 58 seconds to 8 minutes 30 seconds, with 63% meeting recommendations for completion within 4 minutes. Nearly all surveyed facilities met ACRIN and European Society of Breast Imaging standards for breast MRI equipment. The majority met standards for acquisition parameters, although techniques varied, in particular for the timing of initial postcontrast imaging. Further guidelines by the ACR Breast MRI Accreditation Program will be of importance in facilitating standardized and high-quality breast MRI.

Bilateral oculomotor nerve palsies due to vascular conflict

Oculomotor nerve palsy is frequently caused by an aneurismal compression and diabetes mellitus. Brainstem infarction, cavernous sinus tumors and other intracranial lesions are well known causes of oculomotor palsy also. However, neurovascular conflict causing oculomotor nerve disturbances are rare1-4. After the advent of high quality MRI and neuroimaging improvements, the diagnosis of such atypical neurovascular conflicts in symptomatic patients became quite simple5,6. The case of a patient with bilateral oculomotor disorder with MRI imaging of the head showing a right [...]

Sedation for radiological imaging

To obtain high-quality CT and MRI scans, children may need to stay immobile in a particularly uncomfortable environment for a reasonable length of time. Although young infants may sleep after...

Prostate MRI and 3D MR Spectroscopy: How We Do It

This review is a primer on the technical aspects of performing a high-quality MRI and MR spectroscopic imaging examination of the prostate. MRI and MR spectroscopic imaging are useful tools in the localization, staging, and functional assessment of prostate cancer. Performing a high-quality MR spectroscopic examination requires understanding of the technical aspects and limitations of spectral acquisition, postprocessing techniques, and spectral evaluation.

Cortical thickness or grey matter volume? The importance of selecting the phenotype for imaging genetics studies

Choosing the appropriate neuroimaging phenotype is critical to successfully identify genes that influence brain structure or function. While neuroimaging methods provide numerous potential phenotypes, their role for imaging genetics studies is unclear. Here we examine the relationship between brain volume, grey matter volume, cortical thickness and surface area, from a genetic standpoint. Four hundred and eighty-six individuals from randomly ascertained extended pedigrees with high-quality T1-weighted neuroanatomic MRI images participated in the study. Surface-based and voxel-based representations of brain structure were derived, using automated methods, and these measurements were analysed using a variance-components method to identify the heritability of these traits and their genetic correlations. All neuroanatomic traits were significantly influenced by genetic factors. Cortical thickness and surface area measurements were found to be genetically and phenotypically independent. While both thickness and area influenced volume measurements of cortical grey matter, volume was more closely related to surface area than cortical thickness. This trend was observed for both the volume-based and surface-based techniques. The results suggest that surface area and cortical thickness measurements should be considered separately and preferred over gray matter volumes for imaging genetic studies.

Indications for Breast MRI in the Patient with Newly Diagnosed Breast Cancer

Use of breast MRI in the preoperative evaluation of patients recently diagnosed with breast cancer has increased significantly over the past 10 years because of its well-documented high sensitivity for detecting otherwise occult breast cancer in the affected and contralateral breasts. However, published research reports on the impact of this improved cancer detection are limited. Equally important are growing concerns that the quality of breast MRI may vary significantly across practice sites, and therefore the published value of MRI may not be achieved for many patients. This article describes the peer-reviewed, published clinical research trials evaluating breast MRI in patients with newly diagnosed breast cancer on which the National Comprehensive Cancer Network (NCCN) practice guidelines are based. The current NCCN guidelines recommend that breast MRI be considered for patients with a newly diagnosed breast cancer to evaluate the extent of ipsilateral disease and to screen the contralateral breast, particularly for women at increased risk for mammographically occult disease. In addition, the guidelines indicate that breast MRI may be used for patients with axillary nodal adenocarcinoma to identify the primary malignancy. The guidelines stress the importance of having proper equipment, imaging technique, and provider training necessary to achieve high-quality breast MRI, and emphasize that MRI practice sites should have the ability to perform MRI-guided biopsy or needle localization. In addition to describing the data regarding use of breast MRI in women with newly diagnosed cancer, this article provides recommendations for the performance of high-quality breast MRI and suggestions for future research.

Suture Bridge Fixation of a Femoral Condyle Traumatic Osteochondral Defect

Internal fixation of a traumatic osteochondral defect presents a challenge in terms of obtaining anatomic reduction, fixation, and adequate compression for healing. Fixation with countersunk intraarticular screws, Herbert screws, bioabsorbable screws and pins, mini-cancellous screws, and glue tissue adhesive have been reported with varying results. We present an alternative fixation method used in two patients for femoral condylar defects that achieved anatomic reduction with compression via a cruciate-shaped suture bridge construct tied down over a bony bridge. This fixation method allowed early passive range of motion and permitted high-quality MRI for followup of fracture healing and articular cartilage integrity. Arthroscopic examination of one of two patients at 6 months followup showed the gross appearance of a healed, anatomically reduced fracture. With 1 year followup for one patient and 2 years for the other, the patients have resumed activity as tolerated with full, painless range of motion at the knee. Longer-term outcomes are unknown. However, the suture bridge is an alternative means of fixation with encouraging early results for treatment of traumatic osteochondral fragments in the knee. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Focal radiation therapy for patients with persistent/recurrent pituitary adenoma, despite previous radiotherapy

With the stricter endocrine definitions of cure following conventionally planned and fractionated radiotherapy for functioning pituitary adenomas, together with the move in the profession (since the advent of high quality MRI) to postpone radiation therapy until macroscopic disease appears after surgery, it is now realised that cure rates following conventional radiotherapy approximate three out of four rather than the >90% cited for more than a decade. Patients with persistent active tumours may be successfully further treated by focal radiation therapy by one of the stereotactic focal techniques. We have experience of such re-treatment radiation therapy in 50 patients. With careful case selection, we here demonstrate that in acromegaly, for example, normalisation of both GH and IGF levels may be achieved in 37-58% of these previously irradiated patients with low risk of late morbidity. Unquestionably, growth delay occurs in many cases but the long term tumour control rate has yet to be established.

Brief Report: Methods for Acquiring Structural MRI Data in Very Young Children with Autism Without the Use of Sedation

We describe a protocol with which we achieved a 93% success rate in acquiring high quality MRI scans without the use of sedation in 2.5-4.5 year old children with autism, developmental delays, and typical development. Our main strategy was to conduct MRIs during natural nocturnal sleep in the evenings after the child's normal bedtime. Alternatively, with some older and higher functioning children, the MRI was conducted while the child was awake and watching a video. Both strategies relied heavily on the creation of a child and family friendly MRI environment and the involvement of parents as collaborators in the project. Scanning very young children with autism, typical development, and developmental delays without the use of sedation or anesthesia was possible in the majority of cases.