Diagnostic magnetic resonance imaging characteristics of congenital mesoblastic nephroma: a retrospective multi-center International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG) radiology panel study

BACKGROUND

Congenital mesoblastic nephroma is the most common solid renal tumor in neonates. Therefore, patients <3 months of age are advised to undergo upfront nephrectomy, whereas invasive procedures at diagnosis in patients ≥3 months of age are discouraged by the International Society of Pediatric Oncology-Renal Tumor Study Group (SIOP-RTSG). Nevertheless, discriminating congenital mesoblastic nephroma, especially from the more common Wilms tumor, solely based on imaging remains difficult. Recently, magnetic resonance imaging (MRI) has become the preferred modality. Studies focusing on MRI characteristics of congenital mesoblastic nephroma are limited.

OBJECTIVE

This study aims to identify diagnostic MRI characteristics of congenital mesoblastic nephroma in the largest series of patients to date.

MATERIALS AND METHODS

In this retrospective multicenter study, five SIOP-RTSG national review radiologists identified 52 diagnostic MRIs of histologically proven congenital mesoblastic nephromas. MRI was performed following SIOP-RTSG protocols, while radiologists assessed their national cases using a validated case report form.

RESULTS

Patients (24/52 classic, 11/52 cellular, and 15/52 mixed type congenital mesoblastic nephroma, 2/52 unknown) had a median age of 1 month (range 1 day-3 months). Classic type congenital mesoblastic nephroma appeared homogeneous with a lack of hemorrhage, necrosis and/or cysts, showing a concentric ring sign in 14 (58.3%) patients. Cellular and mixed type congenital mesoblastic nephroma appeared more heterogeneous and were larger (311.6 and 174.2 cm3, respectively, versus 41.0 cm3 for the classic type (P<0.001)). All cases were predominantly T2-weighted isointense and T1-weighted hypointense, and mean overall apparent diffusion coefficient values ranged from 1.05-1.10×10-3 mm2/s.

CONCLUSION

This retrospective international collaborative study showed classic type congenital mesoblastic nephroma predominantly presented as a homogeneous T2-weighted isointense mass with a typical concentric ring sign, whereas the cellular type appeared more heterogeneous. Future studies may use identified MRI characteristic of congenital mesoblastic nephroma for validation and for exploring the discriminative non-invasive value of MRI, especially from Wilms tumor.

Ultrasound as the first line investigation for midgut malrotation: a UK tertiary centre experience

AIM

To present the first 22-months experience of transitioning to an ultrasound-first pathway for suspected midgut malrotation.

MATERIALS AND METHODS

An "ultrasound-first" imaging pathway was initiated in October 2021. Twenty-two-months later, a search was undertaken of all <1-year-old patients with "bilious", "malrotation," or "volvulus" as the imaging indication. Reports and images from upper gastrointestinal fluoroscopy (UGI) and ultrasound were reviewed, and diagnoses and outcomes were documented.

RESULTS

The search yielded 101 eligible cases between October 2021 and July 2023. Of the patients, 63/101 (62%) had both ultrasound and UGI: 47/63 (75%) ultrasound first, 16/63 (25%) UGI first. Thirty-one per cent (31/101) had ultrasound only and 7/70 (10%) UGI only. The pathway diagnosed 7/8 (88%) infants with midgut malrotation with or without volvulus and one infant who had an inconclusive ultrasound examination with a suspected an internal hernia and who was found to have malrotation volvulus at surgery. Twenty-one infants who had confidently normal ultrasound examinations and who also had UGI all had a normal duodenojejunal flexure position. Ultrasound detected alternative pathology in eight children. Duodenal visualisation improved with time: 6/15 (40%) in the first 6 months to 23/34 (68%) after the first year.

CONCLUSION

The transition to ultrasound as the first diagnostic test for midgut malrotation can be done safely and effectively in a UK centre, which previously relied solely on UGI.

MRI Characteristics of Pediatric Renal Tumors: A SIOP-RTSG Radiology Panel Delphi Study

BACKGROUND

The SIOP-Renal Tumor Study Group (RTSG) does not advocate invasive procedures to determine histology before the start of therapy. This may induce misdiagnosis-based treatment initiation, but only for a relatively small percentage of approximately 10% of non-Wilms tumors (non-WTs). MRI could be useful for reducing misdiagnosis, but there is no global consensus on differentiating characteristics.

PURPOSE

To identify MRI characteristics that may be used for discrimination of newly diagnosed pediatric renal tumors.

STUDY TYPE

Consensus process using a Delphi method.

POPULATION

Not applicable.

FIELD STRENGTH/SEQUENCE

Abdominal MRI including T1- and T2-weighted imaging, contrast-enhanced MRI, and diffusion-weighted imaging at 1.5 or 3 T.

ASSESSMENT

Twenty-three radiologists from the SIOP-RTSG radiology panel with ≥5 years of experience in MRI of pediatric renal tumors and/or who had assessed ≥50 MRI scans of pediatric renal tumors in the past 5 years identified potentially discriminatory characteristics in the first questionnaire. These characteristics were scored in the subsequent second round, consisting of 5-point Likert scales, ranking- and multiple choice questions.

STATISTICAL TESTS

The cut-off value for consensus and agreement among the majority was ≥75% and ≥60%, respectively, with a median of ≥4 on the Likert scale.

RESULTS

Consensus on specific characteristics mainly concerned the discrimination between WTs and non-WTs, and WTs and nephrogenic rest(s) (NR)/nephroblastomatosis. The presence of bilateral lesions (75.0%) and NR/nephroblastomatosis (65.0%) were MRI characteristics indicated as specific for the diagnosis of a WT, and 91.3% of the participants agreed that MRI is useful to distinguish NR/nephroblastomatosis from WT. Furthermore, all participants agreed that age influenced their prediction in the discrimination of pediatric renal tumors.

DATA CONCLUSION

Although the discrimination of pediatric renal tumors based on MRI remains challenging, this study identified some specific characteristics for tumor subtypes, based on the shared opinion of experts. These results may guide future validation studies and innovative efforts.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 3.

Paediatric gastrointestinal and hepatobiliary radiology: why do we need subspecialists, and what is new?

We present the case for subspecialisation in paediatric gastrointestinal and hepato-pancreatico-biliary radiology. We frame the discussion around a number of questions: What is different about the paediatric patient and paediatric gastrointestinal system? What does the radiologist need to do differently? And finally, what can be translated from these subspecialty areas into everyday practice? We cover conditions that the sub-specialist might encounter, focusing on entities such as inflammatory bowel disease and hepatic vascular anomalies. We also highlight novel imaging techniques that are a focus of research in the subspecialties, including contrast-enhanced ultrasound, MRI motility, magnetisation transfer factor, and magnetic resonance elastography.

18F-FDG PET/MRI for Staging and Interim Response Assessment in Pediatric and Adolescent Hodgkin Lymphoma: A Prospective Study with 18F-FDG PET/CT as the Reference Standard

Treatment regimens for pediatric Hodgkin lymphoma (HL) depend on accurate staging and treatment response assessment, based on accurate disease distribution and metabolic activity depiction. With the aim of radiation dose reduction, we compared the diagnostic performance of ¹⁸F-FDG PET/MRI with a ¹⁸F-FDG PET/CT reference standard for staging and response assessment. Methods: Twenty-four patients (mean age, 15.4 y; range, 8-19.5 y) with histologically proven HL were prospectively and consecutively recruited in 2015 and 2016, undergoing both ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI at initial staging (n = 24) and at response assessment (n = 21). The diagnostic accuracy of ¹⁸F-FDG PET/MRI for both nodal and extranodal disease was compared with that of ¹⁸F-FDG PET/CT, which was considered the reference standard. Discrepancies were retrospectively classified as perceptual or technical errors, and ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT were corrected by removing perceptual error. Agreement with Ann Arbor staging and Deauville grading was also assessed. Results: For nodal and extranodal sites combined, corrected staging ¹⁸F-FDG PET/MRI sensitivity was 100% (95% CI, 96.7%-100%) and specificity was 99.5% (95% CI, 98.3%-99.9%). Corrected response-assessment ¹⁸F-FDG PET/MRI sensitivity was 83.3% (95% CI, 36.5%-99.1%) and specificity was 100% (95% CI, 99.2%-100%). Modified Ann Arbor staging agreement between ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI was perfect (κ = 1.0, P = 0.000). Deauville grading agreement between ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT was excellent (κ = 0.835, P = 0.000). Conclusion: ¹⁸F-FDG PET/MRI is a promising alternative to ¹⁸F-FDG PET/CT for staging and response assessment in children with HL.

Quantitative assessment of terminal ileum motility on MR enterography in Crohn disease: a feasibility study in children

OBJECTIVES

Investigate the relationship between quantified terminal ileal (TI) motility and histopathological activity grading, Crohn Disease MRI Index (CDMI) and faecal calprotectin.

METHODS

Retrospective review of children with Crohn disease or unclassified inflammatory bowel disease, who underwent MR enterography. Dynamic imaging for 25 patients (median age 12, range 5 to 16) was analysed with a validated motility algorithm. The TI motility score was derived. The primary reference standard was TI Endoscopic biopsy Assessment of Inflammatory Activity (eAIS) within 40 days of the MR enterography. Secondary reference standards: (1) the Crohn Disease MRI Index (CDMI) and (2) faecal calprotectin levels.

RESULTS

MR enterography median motility score was 0.17 a.u. (IQR 0.12 to 0.25; range 0.05 to 0.55), and median CDMI was 3 (IQR 0 to 5.5). Forty-three percent of patients had active disease (eAIS > 0) with a median eAIS score of 0 (IQR 0 to 2; range 0 to 5). The correlation between eAIS and motility was r = - 0.58 (p = 0.004, N = 23). Between CDMI and motility, r = - 0.42 (p = 0.037, N = 25). Motility score was lower in active disease (median 0.12 vs 0.21, p = 0.020) while CDMI was higher (median 5 vs 1, p = 0.04). In a subset of 12 patients with faecal calprotectin within 3 months of MR enterography, correlation with motility was r = - 0.27 (p = 0.4).

CONCLUSIONS

Quantified terminal ileum motility decreases with increasing histopathological abnormality in children with Crohn disease, reproducing findings in adults. TI motility showed a negative correlation with an MRI activity score but not with faecal calprotectin levels.

KEY POINTS

• It is feasible to perform MRI quantified bowel motility assessment in children using free-breathing techniques. • Bowel motility in children with Crohn disease decreases as the extent of intestinal inflammation increases. • Quantified intestinal motility may be a candidate biomarker for treatment efficacy in children with Crohn disease.

Evaluation of inter-observer variation for computed tomography identification of childhood interstitial lung disease

Interstitial lung diseases (ILDs) that present in childhood (chILD) are seen far less frequently than ILDs presenting in adults which themselves constitute rare disorders [1]. Histopathological [2, 3] and imaging [4] characterisation of chILD disease subtypes therefore lags behind adult ILDs. The field has also been constrained by comparisons with disease morphology in adults, despite the developmental differences in terms of growth and healing in the paediatric lung, which may alter disease patterns and distributions. The American Thoracic Society [5] and European [1] chILD management guidelines both specify a pivotal role for computed tomography (CT) imaging in the work-up of chILD patients to: 1) determine whether a chILD is present or not; and 2) where possible, to make a specific diagnosis of the underlying cause. For the second aim to be achieved, diagnostic reviews need to be reproducible between experts. Our study uniquely examined agreement between observers of varying experience in the CT evaluation of chILD to inform whether the current status of CT imaging and knowledge can be diagnostic of specific chILDs. We hypothesised that observer agreement for chILD groups and diagnoses would be limited. The study was not designed to relate CT agreement to final diagnosis. As a secondary analysis, we examined how CT interpretation differed between observers in children under and over 2 years of age.

Making chILD diagnoses on CT is poorly reproducible, even amongst sub-specialists. CT might best improve diagnostic confidence in a multidisciplinary team setting when augmented with clinical, functional and haematological results.http://bit.ly/327jRCw

European Society of Paediatric Radiology abdominal imaging task force: statement on imaging in very early onset inflammatory bowel disease

Very early onset inflammatory bowel disease (VEO-IBD) is defined as disease presenting before the age of 6. These children require a tailored imaging approach because conventional imaging studies can be difficult to perform at such a young age. Unlike inflammatory bowel disease in older children and adults, colonic disease predominates in VEO-IBD, and small-bowel disease is rare. Distinguishing Crohn disease from ulcerative colitis is challenging both clinically and on histology. Radiology offers the greatest utility for detecting small-bowel disease because it helps to distinguish the two main disease entities and guide clinical management. Small-bowel ultrasound is recommended as the first-line investigation because it requires relatively little preparation, is readily available and is generally well tolerated in young children. We present these recommendations, based on the current evidence for radiologic management in this group, and propose an imaging algorithm for investigating VEO-IBD.

Detecting inflammation in inflammatory bowel disease - how does ultrasound compare to magnetic resonance enterography using standardised scoring systems?

BACKGROUND

Magnetic resonance enterography (MRE) is the current gold standard for imaging in inflammatory bowel disease, but ultrasound (US) is a potential alternative.

OBJECTIVE

To determine whether US is as good as MRE for the detecting inflamed bowel, using a combined consensus score as the reference standard.

MATERIALS AND METHODS

We conducted a retrospective cohort study in children and adolescents <18 years with inflammatory bowel disease (IBD) at a tertiary and quaternary centre. We included children who underwent MRE and US within 4 weeks. We scored MRE using the London score and US using a score adapted from the METRIC (MR Enterography or Ultrasound in Crohn's Disease) trial. Four gastroenterologists assessed an independent clinical consensus score. A combined consensus score using the imaging and clinical scores was agreed upon and used as the reference standard to compare MRE with US.

RESULTS

We included 53 children. At a whole-patient level, MRE scores were 2% higher than US scores. We used Lin coefficient to assess inter-observer variability. The repeatability of MRE scores was poor (Lin 0.6). Agreement for US scoring was substantial (Lin 0.95). There was a significant positive correlation between MRE and clinical consensus scores (Spearman's rho = 0.598, P=0.0053) and US and clinical consensus scores (Spearman's rho = 0.657, P=0.0016).

CONCLUSION

US detects as much clinically significant bowel disease as MRE. It is possible that MRE overestimates the presence of disease when using a scoring system. This study demonstrates the feasibility of using a clinical consensus reference standard in paediatric IBD imaging studies.

Paediatric magnetic resonance enteroclysis under general anaesthesia - initial experience

MR enterography is the accepted imaging reference standard for small bowel assessment in inflammatory bowel disease. There is an increasing cohort of children with inflammatory bowel disease presenting at an early age (<5 years) with severe disease. Younger children present a technical challenge for enterography because of the need for sedation/general anaesthesia to allow image optimisation and the need for oral contrast to allow adequate luminal assessment. Through our experiences, MR enteroclysis under general anaesthesia has proven to be a successful imaging technique for the work-up of these patients. In this paper, we present our institutional practice for performing MR enteroclysis under general anaesthesia.

Detecting inflammation in the unprepared pediatric colon - how reliable is magnetic resonance enterography?

BACKGROUND

Pediatric inflammatory bowel disease frequently affects the colon. MR enterography is used to assess the small bowel but it also depicts the colon.

OBJECTIVE

To compare the accuracy of MR enterography and direct visualization at endoscopy in assessing the colon in pediatric inflammatory bowel disease.

MATERIALS AND METHODS

We included children with inflammatory bowel disease who had undergone both MR enterography and endoscopy, and we restrospectively assessed the imaging and endoscopic findings. We scored the colonic appearance at MR using a total colon score. We then compared scores for the whole colon and for its individual segments with endoscopy and histology.

RESULTS

We included 15 children. An elevated MR colonic segmental score predicted the presence of active inflammation on biopsy with a specificity of 90% (95% confidence interval [CI] 79.5-96.2%) and sensitivity of 60% (CI 40.6-77.3%); this compares reasonably with the predictive values for findings at colonoscopy - specificity 85% (CI 73.4-92.9%) and sensitivity 53.3% (CI 34.3%-71.6%). Accuracy did not change significantly with increasing bowel distension.

CONCLUSION

MR-derived scores had comparable accuracy to those derived during visualization at colonoscopy for detecting biopsy-proven inflammation in our patient group. MR enterography might prove useful in guiding biopsy or monitoring treatment response. Collapse of a colonic segment did not impair assessment of inflammation.

Radiographic appearances of uncommon paediatric implants and devices

As childhood survival of chronic illness improves, long-term implanted devices will be encountered more frequently in routine radiology. In our paediatric tertiary referral hospital, we have come across several types of implanted devices that were not confidently recognised or identified by front-line staff and were often only identified by discussion with the patient, family or clinical team. This pictorial review highlights the appearance of nonvascular devices on paediatric radiographs in order to help clinicians identify the most frequent complications and to improve awareness of these important devices.

Fusion and subtraction post-processing in body MRI

Interpreting complex paediatric body MRI studies requires the integration of information from multiple sequences. Image processing software, some freely available, allows the radiologist to use simple and rapid post-processing techniques that may aid diagnosis. We demonstrate the use of fusion and subtraction post-processing techniques with examples from four areas of application: enterography, oncological imaging, musculoskeletal imaging and MR fistulography.

Hay fever: pharmacotherapy or immunotherapy?

The total management of the patient with hay fever involves a multifaceted approach including environmental control, pharmacotherapy, and immunotherapy. Pharmacotherapy and immunotherapy are complementary methods which the allergist may utilize as appropriate to each individual patient's needs.

Ablation of luteal phase symptoms of Menière's disease with leuprolide

Symptoms of Menière's disease in women may be exacerbated during the luteal phase of the menstrual cycle. This suggests a role for progesterone production and subsequent fluid redistribution as a predisposing factor for Menière's symptoms. We report the use of leuprolide acetate, a gonadotropin-releasing hormone agonist, in a woman with cyclic Menière's symptoms. This drug, which abolishes gonadotropin-dependent ovarian sex steroid production, alleviated the patient's symptoms during therapy. This observation offers further support to the hypothesis of sex hormone-related exacerbations of Menière's symptoms and provides a possible future treatment option for this debilitating disease.

Effects of pH and feeding regime on methylmercury accumulation within aquatic microcosms

The effect of pH (pH 5, 6 or 7) on accumulation of radiolabelled methylmercury was examined using a laboratory microcosm system. Accumulation of labelled mercury at three trophic levels, primary consumers (Daphnia magna), secondary consumers (rainbow trout, Salmo gairdneri) and tertiary consumers (walleye, Stizostedion vitreum) was not significantly affected by pH. Our results are in direct contrast with field observations of elevated methylmercury concentrations in fish from low pH water and indicate that the elevated mercury residues observed in the field result from factors other than the direct effects of pH on accumulation of methylmercury by aquatic organisms. Both water and diet were important as sources of the labelled mercury which was accumulated by walleye. Walleye which were fed rainbow trout, that had accumulated labelled mercury from within the experimental microcosms, accumulated almost twice as much labelled mercury as walleye fed non-labelled prey, or walleye which were not fed. Walleye fed non-labelled rainbow trout accumulated slightly more labelled mercury than walleye which were not fed, presumably as a result of the higher metabolic rate of the fish which were fed.

In vitro effects of acephate on carbonic anhydrase activity in the blood and gills of rainbow trout, Salmo gairdneri

Acephate, a water-soluble organophosphate pesticide used to control terrestrial insect pests, may enter aquatic ecosystems in the course of its use and adversely affect fish populations. The in vitro effects of this insecticide on gill and red blood cell (RBC) carbonic anyhdrase (CA) activity in rainbow trout were investigated over a range of 100 mg/1 (0.55 mM) to 50,000 mg/l (273 mM) to assess the manner in which acephate might affect respiratory capacity in exposed fish. Concentrations required to produce 50% inhibition of CA activity in the gill and RBC preparations were 38,000 mg/l (207 mM) and 8,900 mg/l (48 mM) respectively. The toxic action of acephate may be related to inhibition of CA activity in the blood and gills with resultant disturbances of respiratory capacity and salt balance.

The effect of radiotherapy in the treatment of adenoid cystic carcinoma of the head and neck arising in minor salivary glands

Eighteen cases of adenoid cystic carcinoma of the minor salivary glands are reviewed. Noteworthy in the history is the report of pain at the site of the lesion which radiates elsewhere, or of numbers or tingling in its area. Radiation therapy is as able to control the primary as local surgery. Involvement of a much wider field than is required to treat the primary may control the perineural spread common to this tumor and avoid the massive procedures necessary to cure it by surgical means. Metastases to the lung, bone, and brain by venous spread can probably be avoided only by early diagnosis.

The effect of sublethal concentrations of zinc on growth and plasma glucose levels in rainbow trout, Salmo gairdneri (Richardson)

The long term effects of three sublethal concentrations of zinc (0.214, 0.52 and 1.12 ppm) on growth and plasma glucose concentration in yearling rainbow trout Salmo gairdneri (Richardson) were investigated. Analysis of covariance of percent weight increase revealed that a significant inhibition of growth (P less than 0.05) in the 1.12 ppm zinc-exposed fish had occurred. Plasma glucose showed a significant hyperglycemia (P less than 0.05) in all three zinc-exposed groups of fish after 7 days exposure and in the 1.12 ppm zinc-exposed group after 63 days. The hyperglycemia observed has been explained as possibly resulting from activation of the pituitary-interrenal axis by the stress of zinc causing mobilization of tissue glycogen.

The 1974 Gordon Richards Memorial Lecture: trends in the organization of cancer services

The development of cancer programs and organizations in Canada is traced from their beginnings until the present time, and tribute is paid to our pioneers, of whom Dr. Richards was an outstanding example in this field. Although provinical cancer control measures vary, there is a marked similarity among some, so that they can be categorized into two or three patterns. The desirable requirements for the establishment and progressive development of cancer centres is described together with their relationship to increasing integration of teaching and research activities. An attempt is made to predict the future pattern of our "cancer clinic" system in which there will be increasing reliance on an interdisciplinary approach.