Evaluation of anterior pituitary gland volume in childhood using three-dimensional MRI

Background: Three-dimensional MRI (3D-MRI) is a reliable tool for the evaluation of anatomical volumes. Volumetric measurement of the normal anterior pituitary gland in childhood has been performed in the past by 2D-MRI calculations, but has inherent inaccuracies. Objective: To obtain accurate normal anterior pituitary gland volume in childhood using 3D-MRI coronal sections. Materials and methods: The anterior pituitary gland was measured using coronal T1-weighted 3D-gradient-echo sequences (section thickness 0.75 mm). The study group was composed of 95 prepubertal children (age range 2 months–10 years) with clinically normal pituitary function and no pituitary or brain abnormalities. Results: A measurement error of 0.2–0.4% was assessed by using a phantom study. Volumetric evaluation of the anterior pituitary gland showed progressive growth of the gland from a mean 131±24 mm³ at 2–12 months, to 249±25 mm³ at 1–4 years and 271±29 mm³ at 5–10 years. Conclusions: These data may be useful for paediatricians in the evaluation of patients with neuroendocrine diseases, in particular growth hormone deficiency.     

Utility of spinal MRI in children with anorectal malformation

Background  The association between spinal cord anomalies and imperforate anus is well recognized. Until now, the incidence of tethered cord has been assumed to be higher in patients with high-type imperforate anus. However, recent reports suggest that tethered cord is as common in patients with a low lesion as in those with a high lesion. Objective  To review the incidence of spinal cord anomalies in those with a low lesion and those with a high (including intermediate) anorectal malformation (ARM), and to determine the best diagnostic imaging strategy. Materials and methods  A group of 50 consecutive patients with postoperative ARM and in whom spinal MRI had been performed were identified retrospectively. We reviewed and compared the following factors between those with a high lesion and those with a low lesion: (1) clinical symptoms, (2) spinal cord anomalies, and (3) vertebral anomalies. Results  The incidence of spinal cord anomalies was no different between those with a high lesion and those with a low lesion, and spinal cord anomalies were present regardless of the presence of vertebral anomalies or symptoms. Conclusion  Owing to the high incidence of spinal cord anomalies in patients with imperforate anus, MRI is the best imaging tool for detecting such anomalies regardless of the level of the lesion.     

MRI diagnosis of bone marrow relapse in children with ALL

Background Diffuse marrow replacement in acute leukemia is well known, but there are few reports describing the MRI features of pediatric leukemic relapse. Objective Our purpose was to describe the MRI appearance of pediatric leukemic relapse. Materials and methods A total of 53 consecutive children with a history of ALL were referred for musculoskeletal MRI from 1 January 1998 to 28 February 2007 at one center, and from 1 January 2000 to 2 May 2007 at a second center. From this group, 14 children seen at initial diagnosis of leukemia and 2 children who underwent MRI after therapy for relapse were excluded. The remaining 37 children, 8 with relapse and 29 in remission, were studied. Images of patients with relapse and in remission were reviewed for type and configuration of marrow infiltration; coexisting marrow alterations including osteonecrosis or stress reaction were also reviewed. Results All eight children with relapse demonstrated nodular lesions with well-defined margins. Coexisting osteonecrosis was present in three children (38%) and pathologic fracture in one. Among the 29 children in remission, 9 showed stress reaction/fracture, 14 showed osteonecrosis and 9 showed ill-defined nodules, and in 5 the marrow was completely normal. Conclusion Well-defined nodules in all patients with leukemic relapse suggest that this appearance is characteristic and distinct from the published findings of diffuse marrow replacement in acute leukemia.     

Pelvic MRI in children with Crohn disease and suspected perianal involvement

MRI is an important imaging tool in evaluation of adult and pediatric patients with Crohn disease. Pelvic MRI, in particular, has become the method of choice to evaluate for perianal fistulas and associated complications of Crohn disease. MRI can define the extent and location of perianal fistulas and abscesses, as well as provide critical information for operative management. In this pictorial essay, we describe useful MRI techniques for evaluation of perianal complications in pediatric patients with Crohn disease. We review pertinent anatomy and illustrate typical examples of perianal fistulas with and without abscess. We show one case of clinically suspected perianal fistula that was actually a pilonidal sinus.     

复合刺激试验对单纯性肥胖儿童下丘脑-垂体 GH轴和性腺轴功能的评价

目的 探讨肥胖儿童下丘脑-垂体轴分泌生长激素（GH）及促性腺激素（Gn）功能。方法 采用复合刺激试验检测27例单纯性肥胖儿童和19例对照儿童：生长激素（GH）用放免法检测,促卵泡生成素（FSH）、促黄体生成素（LH）采用全自动荧光免疫分析系统测定。结果肥胖儿童的GH峰值（PGH）明显低于对照组（,J〈0.01）;PGH〈10μg／L者占肥胖儿童总数的88.89％。所有受试儿童血LH峰值（PLH）／LH基础值（BLH）均〉3;PLH／PFSH（FSH峰值）比值在青春期肥胖和对照组均〉0．7,但在青眷期前肥胖组有4例〉0.7;PLH值达到性腺轴发育标准者,在青春期肥胖组7例、对照组lO例、青春期前肥胖组l例。有4例青春期前肥胖儿存在中枢性性早熟,占30．77％。结论 肥胖儿垂体分泌GH功能和反应能力低下,但其身高正常,提示肥胖儿的生长调控机制较为复杂。采用PLH／PFSH比值和／或PLH值作为性腺轴功能成熟的判断标准较为理想。     

Atypical atrial septal defects in children: noninvasive evaluation by cardiac MRI

Background  Atypical left-to-right shunts at the level of the atrium in children such as sinus venosus atrial septal defects (ASDs) and partial anomalous pulmonary venous return (PAPVR) may be difficult to assess by transthoracic or transoesophageal echocardiography. Free-breathing cardiac MRI may be a powerful alternative. Objective  To assess the value of free-breathing cardiac MRI in the delineation of atypical ASDs in children. Materials and methods  A total of 82 children (mean age 5.9 years, range 1.1–15.7 years) with suspected ASD and inconclusive transthoracic echocardiography underwent cardiac MRI under free-breathing, mostly sedated conditions. Phase-contrast MRI was used for defect visualization and shunt quantification, and multiphase inflow MR angiography for delineation of pulmonary/systemic venous connections. Results  Of the 82 patients, 34 (41%) were diagnosed with atypical shunt lesions at the level of the atrium and 48 (59%) with simple secundum ASDs. No false-negative or false-positive findings were reported by MRI compared to cardiac catheterization and intraoperative findings. Superior sinus venosus ASD with partial anomalous PAPVR was present in 10 of the 82 children (12.2%), whereas 2 (2.4%) had a large posterior-inferior defect, 5 (6.1%) had isolated PAPVR, and 17 (20.7%) had multiple ASDs and/or associated vascular anomalies. Q_p/Q_s by phase-contrast MRI agreed well with oximetry values (mean difference 3%, limits of agreement ±21–25%; Bland/Altman analysis). Conclusion  Free-breathing cardiac MRI under sedation allows reliable identification of atypical left-to-right shunt defects at the level of the atrium in children in whom transcatheter ASD closure is unsuitable, including delineation of pulmonary or systemic venous anomalies and shunt quantification.     

Unidentified bright objects on brain MRI in children as a diagnostic criterion for neurofibromatosis type 1

Background Lesions of the brain denominated as unidentified bright objects (UBOs), which are not included in the diagnostic criteria for neurofibromatosis type 1 (NF1) established by the National Institutes of Health (NIH), have been detected by MRI. Objective The purpose of this study was to investigate the possibility of including the presence of UBOs as a diagnostic criterion for NF1 in children. Materials and methods The study included 88 children between the ages of 2 and 18 years. The case group consisted of 40 children diagnosed with sporadic or familial NF1 according to the criteria established by the NIH. A control group consisted of 48 individuals referred for routine MRI of the brain for other complaints not related to NF1. Results UBOs were identified in 70% of the NF1 patients and in none of the control group. The sensitivity of the presence of UBOs for the diagnosis of NF1 was 70% (CI 53–83%), with a false-negative rate of 30% (CI 27–47%), a specificity of 100% (CI 86–100%) and a false-positive rate of 0% (CI 0–14%). Conclusion Faced with the difficulties in diagnosing NF1 in children and the high frequency and specificity of the presence UBOs identified by MRI in our series, we recommend the inclusion of the presence UBOs as a diagnostic criterion for NF1 in children.     

Imaging of muscle disorders in children

Muscle inflammation is a relatively common pathological process in childhood. The diagnosis of the underlying cause relies on an appreciation of the pattern of clinical features, as well as the results of biochemical, histological and radiological investigations. Often the clinical and biochemical features are non-specific and insensitive. Consequently, the radiological abnormalities are very important in establishing a diagnosis and an understanding of the imaging features of muscle inflammatory disorders in childhood is needed. Some of the imaging protocols needed to investigate a variety of muscle and soft-tissue inflammatory conditions in childhood are reviewed in this article. Those features that are helpful in narrowing the differential diagnosis are indicated and a logical approach to the investigation of affected children is provided. The value of MR imaging is highlighted.     

Aortic dilatation in Turner syndrome: the role of MRI in early recognition

Background: Aortic dilatation and dissection are rare but important complications of Turner syndrome that increase the risk of sudden death in young patients. Objective: To assess the value of aortic MRI in patients with Turner syndrome; in particular to demonstrate early aortic dilatation. Materials and methods: A total of 21 patients with Turner syndrome underwent MRI of the thoracic aorta with measurement of vessel diameter at four levels. Results: Measurements were normal for age in 15 cases, two patients presented with values at the upper limit of normal and four had obvious dilatation of the ascending aorta. All were symptom free. Conclusions: MRI allows the non-invasive demonstration of early aortic dilatation, which may lead to earlier surgery in asymptomatic individuals.     

Virtual cardiotomy based on 3-D MRI for preoperative planning in congenital heart disease

Background  Patient-specific preoperative planning in complex congenital heart disease may be greatly facilitated by virtual cardiotomy. Surgeons can perform an unlimited number of surgical incisions on a virtual 3-D reconstruction to evaluate the feasibility of different surgical strategies. Objective  To quantitatively evaluate the quality of the underlying imaging data and the accuracy of the corresponding segmentation, and to qualitatively evaluate the feasibility of virtual cardiotomy. Materials and methods  A whole-heart MRI sequence was applied in 42 children with congenital heart disease (age 3 ± 3 years, weight 13 ± 9 kg, heart rate 96 ± 21 bpm). Image quality was graded 1–4 (diagnostic image quality ≥2) by two independent blinded observers. In patients with diagnostic image quality the segmentation quality was also graded 1–4 (4 no discrepancies, 1 misleading error). Results  The average image quality score was 2.7 – sufficient for virtual reconstruction in 35 of 38 patients (92%) older than 1 month. Segmentation time was 59 ± 10 min (average quality score 3.5). Virtual cardiotomy was performed in 19 patients. Conclusion  Accurate virtual reconstructions of patient-specific cardiac anatomy can be produced in less than 1 h from 3-D MRI. The presented work thus introduces a new, clinically feasible noninvasive technique for improved preoperative planning in complex cases of congenital heart disease.     

MRI of traumatic patellar dislocation in children

Background Traumatic patellar dislocations (TPD) are common injuries in children, and MRI is useful in evaluation of pediatric musculoskeletal injuries. However, no pediatric studies on the MR features of TPD have been reported. Objective To review the injuries after TPD in children. Materials and methods Patients with clinical or radiological recognition of TPD and those with suggestive MR findings were selected. Bone, cartilage and soft-tissue injuries and patellofemoral relationships were assessed. Results A total of 26 patients (age range 10–18 years) were identified. The following injuries were seen: bone bruising of the inferomedial patella (81% of patients) and the lateral femoral condyle (81% of patients), cartilage injuries of the inferomedial patella (38% of patients) and the lateral femoral condyle (38% of patients), osteochondral fragments (42% of patients) and injuries of the medial patellar restraints (81% of patients). Conclusion Pediatric manifestations of TPD seen on MRI are similar to those in adults. TPD is often occult in children. Early recognition of bone bruising of the patella and lateral femoral condyle, associated osteochondral injuries, and medial patellar stabilizer injury is important for timely diagnosis.     

Pediatric musculoskeletal MRI: basic principles to optimize success

The purpose of this general review is to suggest practical strategies to optimize musculoskeletal MR imaging in children. The changes related to ossification and marrow transformation affect the MRI appearance during development. This review summarizes the normal appearance of the growing skeleton on various pulse sequences, as well as ways to optimize the imaging parameters. Appropriate patient positioning, choice of field of view and imaging coils are essential. There are various tools including intravenous contrast agent administration, fat suppression and parallel imaging that can enhance the depiction of abnormalities, increase speed of imaging, and improve overall quality of the study. Finally, special considerations for imaging at 3 T are also reviewed. “Experience is the name everyone gives to their mistakes.” Oscar Wilde, Lady Windermere’s Fan.     

MRI after operative reduction with femoral osteotomy in developmental dysplasia of the hip

The use of MRI scanning has been described after open reduction of the hip in developmental dysplasia of the hip (DDH) to check hip position, but has not previously been reported after open reduction with femoral osteotomy and the use of metalwork. We report a prospective study to determine whether MRI scanning can be used to confirm satisfactory reduction of the hip following surgery for DDH, even in the presence of metalwork in the proximal femur. MRI scans were performed in 12 consecutive children, and all gave diagnostic information indicating satisfactory reduction. Sedation was not required and the mean scanning time was 3 min 45 s. Satisfactory images, the lack of need for sedation, comparable time and cost to CT scanning and most importantly the lack of exposure of the child to ionizing radiation make MRI a most appealing method for imaging. We therefore recommend it as the investigation of choice in this patient group.     

Post-contrast FLAIR MR imaging of the brain in children: normal and abnormal intracranial enhancement

Objective To describe the normally enhancing intracranial structures on fluid-attenuated inversion recovery (FLAIR) MRI and evaluate the usefulness of postcontrast FLAIR images of the brain in the assessment of enhancing lesions by comparing postcontrast FLAIR imaging with postcontrast T1-weighted (T1-W) imaging in children.Materials and methods In 218 children, 249 pre- and postcontrast FLAIR MRI examinations of the brain were obtained consecutively between August 2001 and April 2002. The normally enhancing intracranial structures on FLAIR imaging were assessed in 77 MRI studies of 74 children who showed normal intracranial imaging findings. In 86 MRI studies in 68 children who showed enhancing intracranial lesions, lesion conspicuity on postcontrast FLAIR imaging was compared with that on postcontrast T1-W imaging for all lesions (n=107), intra-axial lesions (n=40), or extra-axial lesions (n=67).Results The normally enhancing intracranial structures on FLAIR MRI were the choroid plexus (99%, 76/77), pituitary stalk (84%, 65/77), pineal gland (71%, 55/77), dural sinuses (26%, 20/77), and cortical veins (9%, 7/77). Of all the enhancing lesions, lesion conspicuousness on postcontrast FLAIR imaging was better than postcontrast T1-weighted imaging in 42, equal in 28, and worse in 37. Of 40 intra-axial lesions, lesion conspicuousness on postcontrast FLAIR imaging was better in 6, equal in 10, and worse in 24. Of 67 extra-axial lesions, lesion conspicuity on postcontrast FLAIR imaging was better in 36, equal in 18, and worse in 13. Conspicuousness of extra-axial lesions was significantly better than that of intra-axial lesions on postcontrast FLAIR imaging (P<0.001).Conclusions The choroid plexus, pituitary stalk, pineal gland, dural sinuses, and cortical veins show normal enhancement on postcontrast FLAIR MRI in children, and postcontrast FLAIR imaging appears better than postcontrast T1-W imaging in the assessment of extra-axial enhancing lesions in children.Presented at the 46th Annual Meeting of the Society for Pediatric Radiology, San Francisco, California, USA, May 2003     

MR imaging assessment of the lateral head of the gastrocnemius muscle: prevalence of segmental anomalous origins in children and young adults

BACKGROUND: Variations in the lower extremity musculature have been identified, including an anomalous origin of the medial head of the gastrocnemius muscle. Anomalies of the lateral head of the gastrocnemius muscle (LGN) have been less frequently described, especially in children. OBJECTIVE: To describe the MR imaging appearance, frequency and clinical symptoms associated with anatomic variations of the LGN in children and young adults. MATERIALS AND METHODS: A retrospective review of 465 knee MR imaging examinations was performed. The site of origin of the LGN was identified as either normal, lateral segmental anomalous origin (LSAO), or medial accessory anomalous origin (MAAO). The clinical indication for imaging was recorded. RESULTS: An anatomic variation of the LGN was identified in 16 patients (3.4%). Nine patients had LSAO, and five of these had symptoms referable to or abnormalities of the patella. Seven patients had MAAO, and three of these had chronic nontraumatic knee pain. CONCLUSION: Anatomic variations of the LGN are not rare in young patients, occurring with a frequency of 3.4% in our series. It is unknown whether these anomalies play a role in the etiology of patellofemoral pain or unexplained joint pain in children.     

Relevance of CT and MRI in retinoblastoma for the diagnosis of postlaminar invasion with normal-size optic nerve: a retrospective study of 150 patients with histological comparison

Background Detection of optic nerve invasion is mandatory in children primarily enucleated for retinoblastoma to ensure a free resection margin. Objective To assess the accuracy of CT and MRI for the detection of postlaminar invasion in normal-size nerves. Materials and methods A total of 150 patients enucleated for retinoblastoma were included. Imaging data (119 CT and 46 MRI) were retrospectively reviewed and compared with histological findings. Abnormal contrast enhancement of the optic nerve was used as diagnostic criterion for invasion. The associations between postlaminar invasion and several indirect signs were also assessed. Statistical analysis was performed with the Kruskal-Wallis and Fisher exact tests. Results Postlaminar invasion on histology was observed in 8% (12/150). The sensitivity, specificity, accuracy and negative and positive predictive values were 60%, 95%, 91%, 95% and 60% for MRI, and 0%, 100%, 94% and 94% (PPV not assessable) for CT, respectively. Tumour diameter was the only indirect radiological sign significantly associated with postlaminar optic nerve invasion (P=0.002). Conclusion Our results suggest that MRI is more relevant than CT for preoperative detection of optic nerve invasion in patients with retinoblastoma. Tumour diameter is the only indirect sign significantly associated with postlaminar invasion.     

Thyroid function in children with growth hormone deficiency,either idiopathic or caused by diseases of the central nervous system

Thyroid function was assessed in thirty two patients with growth hormone deficiency (GHD) by clinical examination and by measurement of T₄-levels, free T₄-indices, basal TSH values and TSH responses to TRH (100 g/m²). Sixteen patients (50%) were hypothyroid. In thirteen patients, the endocrine disorders were considered to be of hypothalamic origin. Ten of them showed prolonged responses to TRH and in the other three the responses were exaggerated. In three patients hypothyroidism was due to a primary pituitary disorder. Sixteen patients were euthyroid although three of them showed impaired TSH responses. In the cases with idiopathic hypopituitarism (n=20) there was a high incidence of abnormal births in the children with additional hypothalamic hypothyroidism, but not in the euthyroid patients. It is concluded that in patients with previous breech or vacuum extraction delivery, growth hormone deficiency when combined with hypothalamic hypothyroidism may be due to birth trauma.