Whole-body MRI in children: Would a 3D STIR sequence alone be sufficient for investigating common paediatric conditions? A comparative study

Whole body magnetic resonance imaging in healthy children and adolescents. Bone marrow appearances of the axial skeleton

OBJECTIVE

To describe the findings of focal high signal on T2 weighted (T2W) images of the bone marrow in the axial skeleton as assessed by whole-body MRI in healthy and asymptomatic children and adolescents.

MATERIAL AND METHODS

We assessed the bone marrow of the mandible, shoulder girdle, thorax, spine, and pelvis on water-only Dixon T2W sequences as part of a whole-body MRI protocol in 196 healthy and asymptomatic children aged 5-19 years. Intensity (0-2 scale) and extension (1-4 scale) of focal high signal areas in the bone marrow were scored and divided into minor or major findings, based on intensity and extension to identify the potentially conspicuous lesions in a clinical setting.

RESULTS

We registered 415 areas of increased signal in the axial skeleton whereof 75 (38.3%) were major findings. Fifty-eight (29.6%) individuals had at least one major finding, mainly located in the pelvis (54, 72%). We found no differences according to gender. The number of minor findings increased with age (p = 0.020), but there were no significant differences in the number of major findings. The most conspicuous findings were in the pelvis, spine and sternum.

CONCLUSION

Non-specific bone marrow T2W hyperintensities in the axial skeleton are frequently detected on whole-body MRI in healthy, asymptomatic children. Awareness of this is important as some findings may resemble clinically silent lesions in children with suspected multifocal skeletal disease.

Whole-body magnetic resonance imaging findings and patterns of chronic nonbacterial osteomyelitis in a series of Greek pediatric patients

Background:

Chronic nonbacterial osteomyelitis (CNO) is a pediatric autoinflammatory disorder presenting with sterile inflammatory bone lesions. Whole-body MRI (WBMRI) has most recently emerged for disease assessment, but data are limited.

Purpose:

The purpose is to evaluate the imaging findings and patterns of CNO on WBMRI in a series of Greek pediatric patients.

Material and Methods:

Whole-body magnetic resonance imaging studies of all children with documented CNO, performed in a single tertiary center, were retrospectively reviewed. WBMRI included coronal T1 and short-tau inversion recovery (STIR), whole spine sagittal STIR, and ankle/foot sagittal STIR images. High signal intensity lesions on STIR images corresponding to bone marrow edema were recorded. The SPSS v.20 statistical package was used for descriptive statistics.

Results:

Twenty children were included (mean age: 12, range: 6–16 years) with 1–31 lesions (mean: 11.8) on WBMRI. Two children had unifocal disease localized at the clavicle, three paucifocal (1–4 lesions), and 15 multifocal bone involvement. All but two children presented with ankle pain and exhibited lesions at the bones of the ankle joint (90%) followed by the knee (50%) and pelvis (10%). The tibia was the most frequently affected bone (70%) followed by calcaneus (60%), fibula (50%), femur (45%), talus, and metatarsals (45%). No lesions in the cervical, thoracic, lumbar spine, and mandible were documented. Only small sacral lesions were seen in 25% of patients with the extensive peripheral disease. Bilateral metaphyseal and epiphyseal involvement with transphyseal extension were common, but the periosteal reaction and well-defined lesion margins were rare.

Conclusion:

Frequent involvement of the foot and ankle and paucity of substantial spinal involvement were seen in Greek pediatric patients with CNO.

MRI in the Diagnosis and Treatment Response Assessment of Chronic Nonbacterial Osteomyelitis in Children and Adolescents

PURPOSE OF REVIEW

To explain the central role of magnetic resonance imaging (MRI) in the diagnosis and follow-up of chronic nonbacterial osteomyelitis (CNO) in children and adolescents, centering on practical technical aspects and salient diagnostic features.

RECENT FINDINGS

In the absence of conclusive clinical features and widely accepted laboratory tests, including validated disease biomarkers, MRI (whether targeted or covering the entire body) currently plays an indispensable role in the diagnosis and therapy response assessment of CNO. Whole-body MRI, which is the reference imaging standard for CNO, can be limited to a short tau inversion recovery (STIR) coronal image set covering the entire body and a STIR sagittal set covering the spine, an approximately 30-min examination with no need for intravenous contrast or diffusion-weighted imaging. The hallmark of CNO is periphyseal (metaphyseal and/or epi-/apophyseal) osteitis, identified as bright foci on STIR, with or without inflammation of the adjacent periosteum and surrounding soft tissue. Response to bisphosphonate treatment for CNO has some unique MRI findings that should not be mistaken for residual or relapsing disease. Diagnostic features and treatment response characteristics of MRI in pediatric CNO are discussed, also describing the techniques used, pitfalls encountered, and differential diagnostic possibilities considered during daily practice.

Bone and Joint Infections: The Role of Imaging in Tailoring Diagnosis to Improve Patients' Care

Imaging is needed for the diagnosis of bone and joint infections, determining the severity and extent of disease, planning biopsy, and monitoring the response to treatment. Some radiological features are pathognomonic of bone and joint infections for each modality used. However, imaging diagnosis of these infections is challenging because of several overlaps with non-infectious etiologies. Interventional radiology is generally needed to verify the diagnosis and to identify the microorganism involved in the infectious process through imaging-guided biopsy. This narrative review aims to summarize the radiological features of the commonest orthopedic infections, the indications and the limits of different modalities in the diagnostic strategy as well as to outline recent findings that may facilitate diagnosis.

3D Whole-Body MRI of the Musculoskeletal System

With its outstanding soft tissue contrast, spatial resolution, and multiplanar capacities, magnetic resonance imaging (MRI) has become a widely used technique. Whole-body MRI (WB-MRI) has been introduced among diagnostic methods for the staging and follow-up assessment in oncologic patients, and international guidelines recommend its use. In nononcologic applications, WB-MRI is as a promising imaging tool in inflammatory diseases, such as seronegative arthritis and inflammatory myopathies. Technological advances have facilitated the introduction of three-dimensional (3D) almost isotropic sequences in MRI examinations covering the whole body. The possibility to reformat 3D images in any plane with equal or almost equal resolution offers comprehensive understanding of the anatomy, easier disease detection and characterization, and finally contributes to correct treatment planning. This article illustrates the basic principles, advantages, and limitations of the 3D approach in WB-MRI examinations and provides a short review of the literature.

Imaging in non-bacterial osteomyelitis in children and adolescents: diagnosis, differential diagnosis and follow-up-an educational review based on a literature survey and own clinical experiences

Background

Chronic non-bacterial osteomyelitis (CNO) is an autoinflammatory bone disorder affecting children and adolescents. Previously classified as a rare disease, recent studies suggest a higher incidence of the disease. CNO may develop into the clinical presentation of chronic recurrent osteomyelitis (CRMO) with high relapse rate and multifocality.

Main body

Diagnosis of CNO/CRMO is often delayed, with implications for disease severity and relapse rate. This can be significantly improved by knowledge of the disease entity and its characteristics. Imaging plays a key role in diagnosis, differential diagnosis and therapy monitoring. Magnetic resonance imaging (MRI) has several advantages compared to other imaging methods and is increasingly applied in clinical studies. Recent studies show that a whole-body (WB) coverage (WB-MRI) without contrast agent administration is a rational approach. This educational review is based on a systematic analysis of international peer-reviewed articles and presents our own clinical experiences. It provides an overview of disease entity, incidence and clinical diagnosis. The role of imaging, especially of whole-body MRI, is discussed in detail. Finally, practical advice for imaging, including flowcharts explaining when and how to apply imaging, is provided.

Conclusion

Knowing the specifics of CNO/CRMO and the importance of MRI/whole-body MRI allows rapid and efficient diagnosis as well as therapy support and helps to avoid irreversible secondary damage.

Whole-body MR imaging in suspected physical child abuse: comparison with skeletal survey and bone scintigraphy findings from the PEDIMA prospective multicentre study

OBJECTIVES

To assess the contribution of whole-body magnetic resonance imaging (WBMRI) and bone scintigraphy (BS) in addition to skeletal survey (SS) in detecting traumatic bone lesions and soft-tissue injuries in suspected child abuse.

METHODS

In this prospective, multicentre, diagnostic accuracy study, children less than 3 years of age with suspected physical abuse were recruited. Each child underwent SS, BS and WBMRI. A blinded first review was performed in consensus by five paediatric radiologists and three nuclear medicine physicians. A second review investigated discrepancies reported between the modalities using a consensus result of all modalities as the reference standard. We calculated the sensitivity, specificity and corresponding 95% confidence interval for each imaging modality (SS, WBMRI and BS) and for the combinations [SS + WBMRI] and [SS + BS].

RESULTS

One hundred seventy children were included of which sixty-four had at least one lesion. In total, 146 lesions were included. The sensitivity and specificity of each examination were, respectively, as follows: 88.4% [95% CI, 82.0-93.1] and 99.7% [95% CI, 99.5-99.8] for the SS, 69.9% [95% CI, 61.7-77.2] and 99.5% [95% CI, 99.2-99.7] for WBMRI and 54.8% [95% CI, 46.4-63.0] and 99.7% [95% CI, 99.5-99.9] for BS. Sensitivity and specificity were, respectively, 95.9% [95% CI, 91.3-98.5] and 99.2% [95% CI, 98.9-99.4] for the combination SS + WBMRI and 95.2% [95% CI, 90.4-98.1] and 99.4% [95% CI, 99.2-99.6] for the combination SS + BS, with no statistically significant difference between them.

CONCLUSION

SS was the most sensitive independent imaging modality; however, the additional combination of either WBMRI or BS examinations offered an increased accuracy.

KEY POINTS

• SS in suspected infant abuse was the most sensitive independent imaging modality in this study, especially for detecting metaphyseal and rib lesions, and remains essential for evaluation. • The combination of either SS + BS or SS + WBMRI provides greater accuracy in diagnosing occult and equivocal bone injuries in the difficult setting of child abuse. • WBMRI is a free-radiation technique that allows additional diagnosis of soft-tissue and visceral injuries.

Whole-body MRI in the diagnosis of paediatric CNO/CRMO

Chronic recurrent multifocal osteomyelitis (CRMO) is an auto-inflammatory disorder affecting the skeleton of children and adolescents. Whole-body MRI (WBMRI) is key in the diagnosis and follow-up of CRMO. Imaging protocols should include sagittal short Tau inversion recovery of the spine, imaging of the hands and feet, and T1 images for distinguishing normal bone marrow. CRMO lesions can be metaphyseal, epiphyseal and physeal-potentially causing growth disturbance and deformity. Spinal lesions are common, important and can cause vertebral collapse. Lesion patterns include multifocal tibial and pauci-focal patterns that follow a predictable presentation and course of disease. Common pitfalls of WBMRI include haematopoietic marrow signal, metaphyseal signal early on in bisphosphonate therapy and normal high T2 signal in the hands and feet. Pictorial reporting assists in recording lesions and follow-up over time. The purpose of this paper is to review the different WBMRI protocols, imaging findings, lesion patterns and common pitfalls in children with CRMO.

Whole-body magnetic resonance imaging in children - how and why? A systematic review

Whole-body magnetic resonance imaging (MRI) is increasingly being used for a number of indications. Our aim was to review and describe indications and scan protocols for diagnostic value of whole-body MRI for multifocal disease in children and adolescents, we conducted a systematic search in Medline, Embase and Cochrane for all published papers until November 2018. Relevant subject headings and free text words were used for the following concepts: 1) whole-body, 2) magnetic resonance imaging and 3) child and/or adolescent. Included were papers in English with a relevant study design that reported on the use and/or findings from whole-body MRI examinations in children and adolescents. This review includes 54 of 1,609 papers identified from literature searches. Chronic nonbacterial osteomyelitis, lymphoma and metastasis were the most frequent indications for performing a whole-body MRI. The typical protocol included a coronal STIR (short tau inversion recovery) sequence with or without a coronal T1-weighted sequence. Numerous studies lacked sufficient data for calculating images resolution and only a few studies reported the acquired voxel volume, making it impossible for others to reproduce the protocol/images. Only a minority of the included papers assessed reliability tests and none of the studies documented whether the use of whole-body MRI affected mortality and/or morbidity. Our systematic review confirms significant variability of technique and the lack of proven validity of MRI findings. The information could potentially be used to boost attempts towards standardization of technique, reporting and guidelines development.

Whole-body MRI Quantification for Assessment of Bone Lesions in Chronic Nonbacterial Osteomyelitis Patients Treated With Pamidronate: A Prevalence, Reproducibility, and Responsiveness Study

OBJECTIVE

The purpose of this study was (1) to assess the interreader reliability in detecting and scoring the inflammatory bone lesions in pediatric patients with chronic nonbacterial osteomyelitis (CNO) by using whole-body magnetic resonance imaging (WB-MRI), and (2) to evaluate the responsiveness of the MRI-detected CNO lesions to pamidronate therapy.

METHODS

Eighty-eight WB-MRI examinations were independently reviewed and scored by 2 radiologists blinded to clinical details in 32 retrospectively enrolled pediatric patients with CNO. Inflammatory bone lesions, soft tissue abnormality, and bony structural changes were scored before and after pamidronate therapy. Lesion responsiveness was calculated by using standardized response mean and interreader reliability was assessed by k statistics.

RESULTS

There was good to excellent interreader agreement for the detection and quantification of bone lesions. After the first cycle of pamidronate in all 32 patients, 96 of the 279 lesions (34%; after excluding 108 lesions of hand and feet) resolved, whereas in a subset of 11 patients with 2 or more cycles, 76% of lesions resolved after the second cycle. Twenty-one (7.5%) lesions worsened and 46 (16.4%) new lesions developed after 1 cycle in all 32 patients. In these 11 patients, the number of worsened lesions reduced to 2 (2%) and new lesions to 14 (14.9%) after the second cycle as detected on MRI. Vertebral lesions had the highest response to treatment.

CONCLUSION

WB-MRI is a reliable tool for objective quantification and assessment of response to treatment of pediatric CNO bone lesions and could be used to monitor disease activity for clinical and research purposes.

Imaging mimics of chronic recurrent multifocal osteomyelitis: avoiding pitfalls in a diagnosis of exclusion

Chronic recurrent multifocal osteomyelitis (CRMO) is a pediatric autoinflammatory disorder that is characterized by multiple sterile inflammatory bone lesions with a relapsing and remitting course. CRMO belongs to the autoinflammatory family of rheumatologic disorders based on absence of significant titers of autoantibodies and autoreactive T-lymphocytes. In absence of pathognomonic clinical, radiographic or pathological features, diagnosis can be challenging. CRMO shares imaging features with other diseases. It is important for radiologists to be able to differentiate other diseases from CRMO because prognosis varies from completely benign to frankly malignant. In this article we first present the clinical and imaging features of CRMO to help readers gain an understanding of the disease process, then discuss our imaging approach to CRMO and review other disease processes that sometimes share similar imaging findings to CRMO and review differentiating features to help avoid misdiagnoses.

Development of a Scoring Tool for Chronic Nonbacterial Osteomyelitis Magnetic Resonance Imaging and Evaluation of its Interrater Reliability

OBJECTIVE

Serial magnetic resonance imaging (MRI) examinations are often needed in chronic nonbacterial osteomyelitis (CNO) to determine the objective response to treatment. Our objectives in this study were (1) to develop a consensus-based MRI scoring tool for clinical and research use in CNO; and (2) to evaluate interrater reliability and agreement using whole-body (WB)-MRI from children with CNO.

METHODS

Eleven pediatric radiologists discussed definitions and grading of signal intensity, size of signal abnormality within bone marrow, and associated features on MRI through monthly conference calls and a consensus meeting, using a nominal group technique in July 2017. WB-MRI scans from children with CNO were deidentified for training reading and an interrater reliability study. The reading by each radiologist was conducted in a randomized order. Interrater reliability for abnormal signal and severity were assessed using free-marginal κ statistics.

RESULTS

Radiologists reached a consensus on grading CNO-specific MRI findings and on describing bone units based on anatomy. A total of 45 sets of WB-MRI scans, including 4 sets of non-CNO MRI examinations, were selected for the final reading. The mean κ of each category of bones was > 0.7 with majority > 0.9 demonstrating substantial/almost perfect interrater reliability of readings among radiologists. The agreement on signal intensity and the size of signal abnormality within the most commonly affected bones (femur and tibia) were lower than those of other bones.

CONCLUSION

The chronic nonbacterial osteomyelitis magnetic resonance imaging scoring (CROMRIS) tool is a comprehensive standardized scoring tool for MRI in children with CNO. Our interrater study demonstrated good interrater reliability and agreement of readings.

Limited Sequence MRIs for Early Onset Scoliosis Patients Detected 100% of Neural Axis Abnormalities While Reducing MRI Time by 68

STUDY DESIGN

Diagnostic accuracy.

OBJECTIVE

The purpose of this study was to determine if neural axis abnormalities in early onset scoliosis (EOS) patients can be reliably detected with limited magnetic resonance imaging (MRI) sequences (sagittal T1, sagittal T2).

SUMMARY OF BACKGROUND DATA

MRIs are often performed in EOS patients as studies have shown there are neural axis abnormalities in up to 40% of this population. MRIs are expensive, lengthy, and often require general anesthesia. In young children prolonged or repeated exposure to general anesthesia may be associated with neurocognitive damage.

METHODS

A retrospective review of consecutive EOS patients from February to December 2017 who received an MRI of the cervical, thoracic, and lumbar spine was conducted. MRI images were reviewed for neural axis abnormalities. Two sequences (sagittal T1, sagittal T2) of these previously reviewed MRIs were read at a separate time by an attending pediatric neuroradiologist. The imaging findings from these two select sequences were then compared with the prior radiology report based on all of the standard MRI sequences.

RESULTS

Fifty patients met criteria. Ten patients (20%) had neural axis abnormalities detected by the full MRI. All of these neural axis abnormalities were detected on the combination of sagittal T1 + sagittal T2 images. Standard MRIs lasted 66 ± 20 minutes and patients required 90 ± 22 minutes of anesthesia. Sagittal T1 + sagittal T2 sequences lasted 21 ± 7 minutes (P < 0.0001).

CONCLUSION

Limited sequence MRIs with sagittal T1 and T2 sequences for EOS patients had 100% sensitivity for the detection of neural axis abnormalities and would allow for a 68% reduction in the length of MRI and significant reduction in anesthesia time.

LEVEL OF EVIDENCE

3.

Whole-body magnetic resonance imaging: techniques and non-oncologic indications

Whole-body MRI is increasingly utilized for assessing oncologic and non-oncologic diseases in infants, children and adolescents. Focusing on the non-oncologic indications, this review covers technical elements required to perform whole-body MRI, the advantages and limitations of the technique, and protocol modifications tailored to specific indications. Rheumatologic diseases account for the majority of non-oncologic whole-body MRI performed in pediatric patients at the author's institution. Whole-body MRI helps in establishing the diagnosis, documenting disease extent and severity, and monitoring treatment response in enthesitis-related arthritis (ERA) and chronic recurrent multifocal osteomyelitis (CRMO). Other non-oncologic indications for whole-body MRI include osteomyelitis (usually pyogenic), pyrexia of unknown origin, neuromuscular disorders, inherited and inflammatory myopathies such as juvenile dermatomyositis and polymyositis, avascular necrosis, and fat/storage disorders. Use of whole-body MRI in postmortem imaging is rising, while whole-body MRI in non-accidental injury is considered to be of limited value. Imaging findings for a range of these indications are reviewed with whole-body MRI examples.

Kappa statistic to measure agreement beyond chance in free-response assessments

Background

The usual kappa statistic requires that all observations be enumerated. However, in free-response assessments, only positive (or abnormal) findings are notified, but negative (or normal) findings are not. This situation occurs frequently in imaging or other diagnostic studies. We propose here a kappa statistic that is suitable for free-response assessments.

Method

We derived the equivalent of Cohen’s kappa statistic for two raters under the assumption that the number of possible findings for any given patient is very large, as well as a formula for sampling variance that is applicable to independent observations (for clustered observations, a bootstrap procedure is proposed). The proposed statistic was applied to a real-life dataset, and compared with the common practice of collapsing observations within a finite number of regions of interest.

Results

The free-response kappa is computed from the total numbers of discordant (b and c) and concordant positive (d) observations made in all patients, as 2d/(b + c + 2d). In 84 full-body magnetic resonance imaging procedures in children that were evaluated by 2 independent raters, the free-response kappa statistic was 0.820. Aggregation of results within regions of interest resulted in overestimation of agreement beyond chance.

Conclusions

The free-response kappa provides an estimate of agreement beyond chance in situations where only positive findings are reported by raters.