MR Imaging Pattern Research Articles

Acute and Chronic Kernicterus: MR Imaging Evolution of Globus Pallidus Signal Change during Childhood.

Despite its rarity in Western countries, kernicterus resulting from severe neonatal hyperbilirubinemia and its associated neurologic consequences still persists. Subtle MR imaging patterns may be overlooked, leading to diagnostic and prognostic uncertainties. The study systematically analyzes MR imaging pattern over time. A retrospective MR imaging study was conducted in Departments of Pediatric Neurology at the University Children's Hospitals in Leipzig, Germany, or Tübingen, Germany, between 2012 and 2022 in patients who presented beyond the neonatal period suspected of having chronic kernicterus. Eight patients with a total of 15 MR images were identified. The clinical diagnosis of kernicterus was confirmed in all cases on the basis of typical MR imaging findings: Bilateral, diffuse hyperintensity of the globus pallidus was observed in the neonatal period on T1WI (1 MR imaging, at 2 weeks), in infancy on T2WI (4 MR images, at 9-26 months). In children 2 years of age and older, bilateral hyperintensity on T2WI was limited to the borders of the globus pallidus (8 MR images, at 20 months -13 years). Notably, 2 children exhibited normal initial MR imaging findings at 2 months of age. Hence, MR imaging depiction of kernicterus pathology evolves with time, first evident on T1WI, subsequently on T2WI, with a "blind window" during early infancy. The T2WI signal change initially involves the entire globus pallidus and later is limited to the borders. Kernicterus had not been diagnosed in any except 2 patients by previous investigators. All patients presented with a characteristic clinical history and signs and an evolving MR imaging pattern. Nonetheless, the diagnosis of kernicterus was frequently missed. Abnormalities on later MR images appear to be underrecognized.

MRI of unruptured infectious intracranial aneurysms in infective endocarditis. A case-control study

PurposeTo evaluate the usefulness of T2* and FLAIR sequences in the detection of unruptured infectious intracranial aneurysms (UIIAs) in infective endocarditis (IE) including the relationships between the lesion patterns within subarachnoid spaces and the presence of UIIA. MethodsRetrospective review of 15 consecutive patients with definite IE undergoing MR imaging (FLAIR, T2*, DWI, CE-MRA, 3D-T1, CE-3DT1 sequences), in whom DSA detected infectious intracranial aneurysms (IIA). Aneurysmal features (diameter, location, morphology on DSA) and signal patterns onT2*, FLAIR and conventional MR sequences at the site of the UIIA, follow-up MRI and IE background, were analyzed.A control-group of 15 IE-patients without IIA at DSA served for comparison. ResultsAmong 17 UIIAs studied, T2* sequence displayed a susceptibility vessel sign in 15/17 (88.2%), both distal and proximal, which matched with the IIA visualized on DSA. Three patterns of hyposignal areas were identified: (a) signet-ring or target-sign appearance (n = 7), (b) homogeneous, round-, oval- or pear-shaped area (n = 4), and (c) heterogeneous area (n = 4). A FLAIR hyperintensity of the lumen and of the adjacent cortex was present in 6 (35.3%) and 9 (53%) UIIAs, respectively. On T1 (12 UIIAs) a rounded hyposignal (n = 2), within the UIIA lumen matched with the FLAIR hypersignal.Using both T2* and FLAIR had an incremental value with 100% sensitivity and specificity. ConclusionThe susceptibility vessel sign is an MR imaging pattern frequently observed at the site of UIIAs in IE-patients.Both T2* and FLAIR may have the potential to depict UIIAs, regardless of their location and shape.

Distinct and Recognisable Muscle MRI Pattern in a Series of Adults Harbouring an Identical GMPPB Gene Mutation.

Mutations in the GMPPB gene affect glycosylation of α-dystroglycan, leading to varied clinical phenotypes. We attempted to delineate the muscle MR imaging spectrum of GMPPB-related Congenital Myasthenic syndrome (CMS) in a single-center cohort study. To identify the distinct patterns of muscle involvement in GMPPB gene mutations. We analyzed the muscle MR images of 7 genetically proven cases of GMPPB dystroglycanopathy belonging to three families and studied the potential qualitative imaging pattern to aid in clinico -radiological diagnosis in neuromuscular practice. All individuals underwent muscle MRI (T1, T2, STIR/PD Fat sat. sequences in 1.5 T machine) of the lower limbs. Qualitative assessment and scoring were done for muscle changes using Mercuri staging for fibro-fatty replacement on T1 sequence and Borsato score for myoedema on STIR sequence. All patients were of South Indian origin and presented as slowly progressive childhood to adult-onset fatigable limb-girdle muscle weakness, elevated creatine kinase level, and positive decrement response in proximal muscles. Muscle biopsy revealed features of dystrophy. All patients demonstrated identical homozygous mutation c.1000G > A in the GMPPB gene. MRI demonstrated early and severe involvement of paraspinal muscles, gluteus minimus, and relatively less severe involvement of the short head of the biceps femoris. A distinct proximo-distal gradient of affliction was identified in the glutei, vasti, tibialis anterior and peronei. Also, a postero-anterior gradient was observed in the gracilis muscle. Hitherto unreported, the distinctive MR imaging pattern described here, coupled with relatively slowly progressive symptoms of fatigable limb-girdle weakness, would facilitate an early diagnosis of the milder form of GMPPB- dystroglycanopathy associated with homozygous GMPPB gene mutation.

Idiopathic Neonatal Subpial Hemorrhage with Underlying Cerebral Infarct: Imaging Features and Clinical Outcome.

Neonatal subpial hemorrhage with underlying cerebral infarct is a previously described but poorly understood clinicoradiographic syndrome. We sought to further characterize the cranial ultrasound and MR imaging characteristics and associated outcomes of this condition across the full range of gestational ages, including extreme and very preterm neonates. This was a single tertiary pediatric center retrospective case series. Brain MR imaging and cranial ultrasound of neonates with subpial hemorrhage with underlying cerebral infarct were identified from a population-based radiology registry (2006-2020). Original images were reviewed by 2 neuroradiologists blinded to history and outcome. Clinical presentation, course, and outcome at >12 months were abstracted from medical records. The diagnostic utility of cranial ultrasound was compared with that of MR imaging. Sixteen patients were included (median gestational age, 36.5 weeks; range, 27-41 weeks; 31% premature). MR images were obtained acutely at the time of presentation between days 0 and 9 of life. On T2WI and DWI, a consistent presence of a hypointense subpial bleed and an underlying hyperintense cerebral cortex were recognized, which created a distinct MR imaging pattern resembling the yin-yang symbol. Findings of all the MRAs and MRVs were normal. Cranial ultrasound detected 6 of 7 MR imaging lesions with sonographic features correlating well with MR imaging. The 3 extreme or very preterm neonates did not survive. The remainder survived with relatively mild neurologic deficits. Subpial hemorrhage with underlying infarction is a recognizable condition with unique MR imaging and sonographic features. Improved recognition may advance understanding of risk factors and outcomes.

MR imaging pattern of tibial subchondral bone structure: considerations of meniscal coverage and integrity

To compare regional differences in subchondral trabecular structure using high-resolution MRI in meniscus-covered/meniscus-uncovered tibia in cadaveric knees with intact/torn menisci. 3D proton density CUBE MRI of 6 cadaveric knees without significant osteoarthritis (OA) was acquired, 0.25-mm resolution. Menisci were evaluated and classified intact or torn. MR data were transferred to ImageJ program to segment tibial 3D volume of interest (VOI). Data was subdivided into meniscus-covered/meniscus-uncovered regions. Segmented VOI was classified into binary data, trabeculae/bone marrow. The trabecular bone data was used to measure MR biomarkers (apparent subchondral plate-connected bone density (adapted from spine MR), apparent trabecular bone volume fraction, apparent mean trabecular thickness, apparent connectivity density, and structure model index (SMI)). Mean value of parameters was analyzed for the effects of meniscal tear/tibial coverage. Nine torn menisci and 3 intact menisci were present. MR measures of bone varied significantly due to meniscal coverage/tear. Subchondral plate-connected bone density under covered meniscus regions increased from 10.9 to 23.5% with meniscal tear. Values increased in uncovered regions, 19.3% (intact) and 32.4% (torn). This reflects higher density when uncovered (p = 0.048) with meniscal tear (p = 0.007). Similar patterns were found for trabecular bone fraction (coverage p < 0.001, tear p = 0.047), trabecular thickness (coverage p = 0.03), connectivity density (coverage p = 0.002), and SMI (coverage p = 0.015). Quantitative trabecular bone evaluation emphasizes intrinsic structural differences between meniscus-covered/meniscus-uncovered tibias. Results offer insight into bone adaptation with meniscal tear and support the hypothesis that subchondral bone plate-connected bone density could be important in early subchondral bone adaptation.

Signal Change in the Mammillary Bodies after Perinatal Asphyxia.

Research into memory deficits associated with hypoxic-ischemic encephalopathy has typically focused on the hippocampus, but there is emerging evidence that the medial diencephalon may also be compromised. We hypothesized that mammillary body damage occurs in perinatal asphyxia, potentially resulting in mammillary body atrophy and subsequent memory impairment. We retrospectively reviewed brain MRIs of 235 clinically confirmed full-term patients with hypoxic-ischemic encephalopathy acquired at a single center during 2004-2017. MRIs were performed within 10 days of birth (median, 6; interquartile range, 2). Two radiologists independently assessed the mammillary bodies for abnormal signal on T2-weighted and DWI sequences. Follow-up MRIs were available for 9 patients; these were examined for evidence of mammillary body and hippocampal atrophy. In 31 neonates (13.2%), abnormal high mammillary body signal was seen on T2-weighted sequences, 4 with mild, 25 with moderate, and 2 with severe hypoxic-ischemic encephalopathy. In addition, restricted diffusion was seen in 6 neonates who had MR imaging between days 5 and 7. For these 31 neonates, the most common MR imaging pattern (41.9%) was abnormal signal restricted to the mammillary bodies with the rest of the brain appearing normal. Follow-up MRIs were available for 9 patients: 8 acquired between 3 and 19 months and 1 acquired at 7.5 years. There was mammillary body atrophy in 8 of the 9 follow-up MRIs. Approximately 13% of full-term infants with hypoxic-ischemic encephalopathy showed abnormal high mammillary body signal on T2-weighted images during the acute phase, which progressed to mammillary body atrophy in all but 1 of the infants who had follow-up MR imaging. This mammillary body involvement does not appear to be related to the severity of encephalopathy, MR imaging patterns of hypoxic-ischemic encephalopathy, or pathology elsewhere in the brain.

MR-imaging pattern is not a predictor of occult atrial fibrillation in patients with cryptogenic stroke

BackgroundTo date, insertable cardiac monitors (ICMs) are the most effective method for the detection of occult atrial fibrillation (AF) in cryptogenic stroke. The overall detection rate after 12 months, however, is low and ranges between 12.4 and 33.3%, even if clinical predictors are considered. Ischemic stroke patients due to cardiogenic embolism present with particular lesion patterns. In patients with cryptogenic stroke, MR-imaging pattern may be a valuable predictor for AF.MethodsThis is an MRI-based, retrospective, observational, comparative, single-center study of 104 patients who underwent ICM implantation after cryptogenic stroke. The findings were compared to a reference group with related stroke etiology, i.e., 166 patients with embolic stroke due to AF detected for the first time by long-term ECG. Lesion patterns were evaluated with regard to affected territories, distribution (cortical, lacunar, scattered), lesion volume, and lesion size (diameter of the lesion size > 20 mm).ResultsThe MR-imaging analysis of acute ischemic lesions yielded no association between AF and lesion size or volume, arterial vessel distribution, or the number of affected territories. There was no significant difference between the cohorts regarding ischemic patterns (cortical lesions, scattered lesions, and lacunar infarcts). An important clinical inference of our findings is that 10% (2 of 20) of cases in the ICM group in whom AF was detected had a lacunar infarct pattern. Similar results were shown in cases of ischemic stroke patients with AF detected for the first time by long-term ECG, with 10.9% (16 of 147) of them showing lacunar infarcts. The analysis of chronic MRI lesions revealed no differences between the groups in the rate of chronic lesions, arterial vessel distribution, or the number of affected territories. Left atrial size (LA size) and the presence of atrial runs in long-term ECG were independently associated with AF.ConclusionsIn this MRI-based analysis of patients with cryptogenic stroke who had received ICM implantation, the detection rate of AF in patients with ICM was not related to the imaging pattern. In addition, the lacunar infarct pattern should not be an exclusion criterion for ICM insertion in patients with cryptogenic stroke. ICM insertion in patients with cryptogenic stroke should not be evaluated solely on the basis of reference to infarct patterns.

KARS-related diseases: progressive leukoencephalopathy with brainstem and spinal cord calcifications as new phenotype and a review of literature

BackgroundKARS encodes lysyl- transfer ribonucleic acid (tRNA) synthetase, which catalyzes the aminoacylation of tRNA-Lys in the cytoplasm and mitochondria. Eleven families/sporadic patients and 16 different mutations in KARS have been reported to date. The associated clinical phenotype is heterogeneous ranging from early onset encephalopathy to isolated peripheral neuropathy or nonsyndromic hearing impairment. Recently additional presentations including leukoencephalopathy as predominant cerebral involvement or cardiomyopathy, isolated or associated with muscular and cerebral involvement, have been reported. A progressive Leukoencephalopathy with brainstem and spinal cord calcifications was previously described in a singleton patient and in two siblings, without the identification of the genetic cause. We reported here about a new severe phenotype associated with biallelic KARS mutations and sharing some common points with the other already reported phenotypes, but with a distinct clinical and neuroimaging picture. Review of KARS mutant patients published to date will be also discussed.ResultsHerein, we report the clinical, biochemical and molecular findings of 2 unreported Italian patients affected by developmental delay, acquired microcephaly, spastic tetraparesis, epilepsy, sensory-neural hypoacusia, visual impairment, microcytic hypochromic anaemia and signs of hepatic dysfunction. MRI pattern in our patients was characterized by progressive diffuse leukoencephalopathy and calcifications extending in cerebral, brainstem and cerebellar white matter, with spinal cord involvement. Genetic analysis performed on these 2 patients and in one subject previously described with similar MRI pattern revealed the presence of biallelic mutations in KARS in all 3 subjects.ConclusionsWith our report we define the molecular basis of the previously described Leukoencephalopathy with Brainstem and Spinal cord Calcification widening the spectrum of KARS related disorders, particularly in childhood onset disease suggestive for mitochondrial impairment. The review of previous cases does not suggest a strict and univocal genotype/phenotype correlation for this highly heterogeneous entity.Moreover, our cases confirm the usefulness of search for common brain and spine MR imaging pattern and of broad genetic screening, in syndromes clinically resembling mitochondrial disorders in spite of normal biochemical assay.

Neonatal parechovirus leucoencephalitis- radiological pattern mimicking hypoxic-ischemic encephalopathy

AimOur objective is to study the MR imaging pattern in neonatal parechoviral leucoencephalitis, a rare cause of neonatal white matter abnormality and to differentiate it from hypoxic-ischemic encephalopathy which is the commonest cause of white matter change in neonates. MethodWe evaluated 25 neonates who presented with features of encephalopathy. Cranial ultrasound and MR imaging was done in all the cases. The pattern of white matter abnormality was analyzed in all cases. ResultsNeonatal leucoencephalitis caused by HPeV has a distinctive clinical presentation and has predilection for the white matter, causing diffusion restricting signal intensity changes involving the periventricular and subcortical white matter, in particular the frontal white matter, also the corpus callosum, internal capsule, external capsule and pyramidal tracts of the supratentorial brain and cerebral peduncle with relative sparing of occipital white matter, thalamus, basal ganglia and the infratentorial regions. Follow up imaging shows disappearance of the lesion without white matter loss. Whereas mild to moderate hypoxic-ischemic injury in a full-term neonate causes lesions in the watershed areas, and subcortical white matter predominantly involving the parietooccipital region and perirolandic region. Thalamus, brainstem, cerebellum, and deep gray matter structures are involved depending on the severity. ConclusionWhite matter changes in the neonatal period are commonly associated with hypoxic-ischemic injuries and metabolic causes, less frequently, infection like parechovirus leucoencephalitis. HPeV infection must be considered in infants with specific pattern of white matter change but no convincing history of a perinatal hypoxic-ischemic insult, thus differentiating it from HIE.

Assessment of acute intestinal graft versus host disease by abdominal magnetic resonance imaging at 3 Tesla.

After allogeneic stem cell transplantation (SCT), a reliable diagnosis of acute graft versus host disease (aGvHD) is essential for an early and successful treatment. It is the aim of this analysis to assess intestinal aGvHD by magnetic resonance imaging (MRI). Prior to allogeneic SCT, 64 consecutive patients underwent abdominal MRI examination on a 3 T MR system, including axial and coronal T2w sequences and a three-dimensional dynamic T1w, contrast enhanced sequence. After SCT, 20 patients with suspected aGvHD received a second MRI as well as an endoscopic examination. Nine patients suffered from histologically proven intestinal aGvHD. In eleven patients intestinal aGvHD was excluded. In all aGvHD patients typical MRI findings with long-segment bowel wall thickening--always involving the terminal ileum--with profound submucosal oedema, were detected. The bowel wall was significantly thickened in patients with intestinal aGvHD. Bowel contrast enhancement spared the submucosa while demonstrating strong mucosal hyperemia. In intestinal aGvHD, a characteristic MR-appearance can be detected. This MRI pattern might facilitate an early and non-invasive diagnosis of intestinal aGvHD. MRI might thus be used as a sensitive tool to rule out or support the clinical diagnosis of aGvHD. • Acute intestinal graft versus host disease (aGvHD) can be assessed by MRI. • The aGvHD of the bowel demonstrates a characteristic MR imaging pattern. • Bowel wall shows extensive long-segment wall thickening with profound submucosal oedema. • Terminal ileum seems invariably affected; other bowel segments show variable involvement. • Colonoscopy in suspected aGvHD should include inspection of terminal ileum.

Non-hyperfunctioning neuroendocrine tumours of the pancreas: MR imaging appearance and correlation with their biological behaviour

To describe MR imaging features of non-hyperfunctioning neuroendocrine pancreatic tumours by comparing them to histopathology and to determine the accuracy of MR imaging in predicting biological behaviour. After institutional review board approval, we retrospectively reviewed 45 patients with pathologically proven NF-NET of the pancreas and ≥1 preoperative MR/MRCP examinations. Of the NF-NETS, 29/45 (64.4 %) were G1 and 16/45 (35.5 %) were G2. Image analysis included the lesion maximum diameter, vascular encasement, extrapancreatic spread, signal intensity on T1- and T2-weighted, contrast enhancement features, and presence of metastases. Tumour vessel density was calculated on the histological specimen using a grid. The median maximum diameter of NF-NETs was 20 mm (range 5-200 mm). Eighty per cent of the NF-NETs were hypointense on T1-weighted images, 82.2 % were hyperintense on T2-weighted images, and 75.6 % were hypervascular. Overall MRI accuracy showed a mean AUC of 0.86 compared to pathology. Lesions with a maximum diameter of 30 mm irregular margins, absence of a cleavage plane with the main pancreatic duct, vascular encasement, extrapancreatic spread and abdominal metastases were significantly associated with malignant NF-NETs. No correlation was found between the tumour vessel density and contrast-enhanced MR imaging pattern. Hyperintensity on T2-weighted images and iso-/hypervascularity occurred in 27/45 (60.0 %) of NF-NETs. MRI identifies malignant NF-NETs with a sensitivity of 93.3 % and a specificity of 76.9 % (AUC = 0.85). • Non-hyperfunctioning neuroendocrine pancreatic tumours (NF-NET) pose a difficult diagnostic challenge. • On T2-weighted MRI, 82.2 % of neuroendocrine tumours appeared hyperintense. • MR imaging showed 0.94 sensitivity and 0.77 specificity in predicting biological behaviour. • The hyper-/isointensity during dynamic MRI did not correlate with vessel density at pathology.

Brain MRI Findings in Neurologically Asymptomatic Patients with Infective Endocarditis

Neurologic complications in infective endocarditis are frequent and affect patient prognosis negatively. Additionally, detection of asymptomatic lesions by MR imaging could help early management of this condition. The objective of our study was to describe MR imaging characteristics of cerebral lesions in a neurologically asymptomatic population with infective endocarditis. One hundred nine patients at the acute phase of a definite or possible infective endocarditis according to the Duke modified criteria and without neurologic manifestations according to the NIHSS were prospectively included. Each patient underwent cerebral MR imaging and MRA within 7 days of admission. MR imaging showed abnormalities in 78 patients (71.5%). Acute ischemic lesions (40 patients, 37%) and cerebral microbleeds (62 patients, 57%) were the most frequent lesions. Eight patients had an acute SAH, 3 patients had brain microabscesses, 3 had a small cortical hemorrhage, and 3 had a mycotic aneurysm. Acute ischemic lesions mostly appeared as multiple small infarcts disseminated in watershed territories (25/40, 62.5%) and as lesions of different ages (21/40, 52.5%). Cerebral microbleeds were preferentially distributed in cortical areas (362/539 cerebral microbleeds, 67%). No significant correlation was found among lesions, in particular between acute ischemia and cerebral microbleeds. Occult cerebral lesions, in particular cerebral microbleeds and acute ischemic lesions, are frequent in infective endocarditis. The MR imaging pattern of acute small infarcts of different ages predominating in watershed territories and cortical cerebral microbleeds may represent a surrogate imaging marker of infective endocarditis.

Optimizing MR Imaging Detection of Type 2 Focal Cortical Dysplasia: Best Criteria for Clinical Practice

Type 2 FCD is one of the main causes of drug-resistant partial epilepsy. Its detection by MR imaging has greatly improved surgical outcomes, but it often remains overlooked. Our objective was to determine the prevalence of typical MR imaging criteria for type 2 FCD, to provide a precise MR imaging pattern, and to optimize its detection. We retrospectively reviewed 1.5T MR imaging of 71 consecutive patients with histologically proved type 2 FCD. The protocol included millimetric 3D T1-weighted, 2D coronal and axial T2-weighted, and 2D or 3D FLAIR images. Two experienced neuroradiologists looked for 6 criteria: cortex thickening, cortical and subcortical signal changes, blurring of the GWM interface, the "transmantle" sign, and gyral abnormalities. The frequency of each sign and their combination were assessed. We compared the delay between epilepsy onset and surgery, taking into account the time of type 2 FCD detection by MR imaging. Only 42 patients (59%) had positive MR imaging findings. In this group, a combination of at least 3 criteria was always found. Subcortical signal changes were constant. Three characteristic signs (cortical thickening, GWM blurring, and transmantle sign) were combined in 64% of patients, indicating that MR imaging can be highly suggestive. However, typical features of type 2 FCD were overlooked on initial imaging in 40% of patients, contributing to a delay in referral for surgical consideration (17 versus 11.5 years when initial MR imaging findings were positive). A combination of 3 major MR imaging signs allows type 2 FCD to be recognized in clinical practice, thereby enabling early identification of candidates for surgery.

Deep Medullary Vein Involvement in Neonates with Brain Damage: An MR Imaging Study

Different and specific MR imaging patterns of lesions involving WM are widely defined in neonatal encephalopathy. The aim of this study was to describe a novel MR imaging pattern of damage characterized by the abnormal prominence of DMVs in premature and full-term neonates. Twenty-one (11 premature and 10 full-term) neonates with MR imaging evidence of linear radially oriented fan-shaped lesions in the periventricular WM and without dural venous thrombosis were enrolled in this retrospective study. A total of 37 MR imaging examinations were performed at ages ranging from day 0 to 24 months. According to the appearance of linear anomalies on T2-weighted images, we identified 2 main patterns: T2 hypointense lesions without WM cavitations and T2 hypointense lesions associated with linear cysts. The first pattern was found in 17 examinations performed between 0 and 44 days of life; the second pattern was found in another 14 examinations performed between 6 days and 4 months of life. Five examinations performed between 9 and 24 months of life showed a reduction in volume and hyperintense signal intensity of the periventricular WM on T2-weighted and FLAIR images. Subtle linear WM lesions with the same anatomic distribution of DMVs may be evident in premature and full-term neonates without signs of major venous thrombosis, both in the acute and subacute phases. Their appearance and evolution suggest that transient DMV engorgement/thrombosis may be responsible for WM damage that can lead to a PVL-like pattern.

Normal cranial bone marrow MR imaging pattern with age-related ADC value distribution

To determine MRI appearances of normal age-related cranial bone marrow and the relationship between MRI patterns and apparent diffusion coefficient (ADC) values. Five hundred subjects were divided into seven groups based on ages. Cranial bone marrow MRI patterns were performed based on different thickness of the diploe and signal intensity distribution characteristics. ADC values of the frontal, parietal, occipital and temporal bones on DWI were measured and calculated. Correlations between ages and ADC values, between patterns and ADC values, as well as the distribution of ADC values were analyzed. Normal cranial bone marrow was divided into four types and six subtypes, Type I, II, III and IV, which had positive correlation with age increasing (χ2=266.36, P<0.01). The ADC values of normal parietal and occipital bone marrow showed significant negative correlation with age growing (r=-0.561 and -0.622, P<0.01), while there were no significant differences of that with age increasing in frontal and temporal bone marrow (P>0.05). In addition, there was significant negative correlation between the ADC values and MRI patterns in the normal parietal and occipital bones (r=-0.691 and -0.750, P<0.01). The combination of MRI features and ADC values changes in different cranial bones showed significant correlation with age increasing. Familiar with the MRI appearance of the normal bone marrow conversion pattern in different age group and their ADC value will aid the diagnosis and differential of the cranial bone pathology.

‘Eye-of-the-Tiger’ Sign and Classic Pantothenate Kinase Associated Neurodegeneration

A five-year-old girl presented with one-year history of gradual onset repeated falls while walking, dysarthria, increasing stiffness, toe walking and abnormal posturing of limbs. There was no diurnal variation and symptoms progressively worsened. On examination, she had masklike facies with horizontal smile and generalized dystonia. Ocular examination revealed waxy pallor of the disc, arteriolar attenuation and alteration in retinal pigmentation with normal foveal reflex suggesting retinitis pigmentosasine-pigmento (Fig. 1). Magnetic resonance imaging (MRI) of brain revealed bilateral symmetrical hypointensity in the globus-pallidus with central hyperintensity, giving an ‘eyeof-tiger’ appearance on T2 weighted and FLAIR images (Fig. 2). Retinitis pigmentosa in eyes and characteristic MRI findings gave the diagnosis of Pantothenate kinase associated neurodegeneration (PKAN). PKAN, formerly known as Hallovorden-Spatz syndrome is an autosomal recessive disorder caused by mutation of the pantothenate kinase-2 gene [1]. The MRI finding, ‘eye-of-the-tiger’sign is pathognomonic of classic PKAN [2]. The hypointensity on T2 weighted image is because of iron deposition and the central hyperintensity is due to the glioses and spongioses due to cell death [3]. There is an absolute correlation between the presence of a mutation in PANK2 and the eye-of-the-tiger sign; that is, all patients with the PANK2 mutation have this MR imaging pattern, which also is not seen in any mutation-negative patients [4]. Eye-of-tiger-sign can sometimes be seen in few cases of neuroferritinopathy, but in these cases careful scurtinization will reveal involvement of other basal ganglia nuclei (caudate and putamen), thalamus and cerebral cortex which is not seen in PKAN [1]. Another condition, where the ‘eye of tiger’ like appearance is seen is dihydropteridine reductase deficiency in which there will be associated features like cortical calcifications and cysts. Even the clinical presentation varies with microcephaly, parkinsonism, oculogyric crisis and disturbed psychomotor development [5]. The eye-of-the-tiger sign can also be seen in non-NBIA conditions such as corticobasal ganglia degeneration and progressive supranuclear palsy [1]. However the clinical features like age of onset differentiate these from PKAN. In conclusion, though important neuroimaging finding like ‘eye-of-the-tiger’ sign can be seen in other conditions, the presence of this finding along with other clinical clues Fig. 1 Ophthalmoscopic findings of right fundus: Retinal examination shows waxy pallor of the disc, arteriolar attenuation and alteration in retinal pigmentation. Macula is normal with normal foveal reflex. Features are consistent with retinitis pigmentosa sine pigmento

Prognostic factors for the outcome of surgical and conservative treatment of symptomatic spinal cord cavernous malformations: a review of a series of 20 patients

In this study, the authors present a review of a series of 20 intramedullary spinal cord cavernous malformations (SCCMs) with particular focus on MR imaging and prognostic factors. Between 1994 and 2009, 20 patients with SCCM were treated under the care of the senior author. The diagnosis was made in all patients after the onset of clinical symptoms. The age of the 9 men and 11 women ranged between 26 and 71 years (median 38.5 years). The duration of symptoms prior to referral ranged from 1 week to 9 years (median 6.5 months). At the time of referral, 4 patients had no significant neurological deficits, 10 patients suffered significant functional restrictions, and 6 patients presented with severe paraparesis and loss of functional strength. None of the patients had complete paraplegia. Seventeen patients underwent microsurgical removal, while 3 patients opted for conservative therapy. For the present analysis, the medical records and MR images and/or reports were reviewed. Classification of length of history, pretreatment status, MR imaging pattern, and treatment modality was done and correlated with outcome. The cavernoma was located at the cervical level in 8 patients and between T-1 and L-1 in 12 patients. The cavernoma appeared as mainly T2 hyperintense on MR images in 7 patients, mainly T2 hypointense in 2 patients, and mixed in the remaining 10 patients. The craniocaudal extension of the core varied between 5 and 45 mm. In 2 patients with cervical cavernomas, a distinct T2 signal of the spinal cord cranial and distal to the cavernoma was seen, and in a patient with a large thoracic cavernoma, T2 extinction cranial and caudal to the cavernoma was seen as a sign of hemosiderosis. Neurological deficits improved postoperatively in 12 of the surgically treated patients, remained stable in 2, and deteriorated in 3. The 3 patients who were conservatively treated remained stable over a follow-up of 3-9 years. Postoperative improvement was seen in 5 of 7 surgical patients with a history of symptoms of 2 months or less, 5 of 6 patients with a history of 2-24 months, and in 2 of 4 patients with a history of more than 2 years. Two of the 3 patients with postoperative deterioration had a history of more than 2 years and the third a short history of 1 month. Although a satisfactory outcome can be achieved through surgical treatment of SCCMs, some patients worsen after surgery or during the postoperative course. Long-term stability is possible in oligosymptomatic conservatively treated patients. The prevalence and pathophysiological importance of segmental spinal cord edema and hemosiderosis is incompletely understood at the present time.

Leigh syndrome: MRI findings in two children

Leigh syndrome is a progressive neurodegenerative disorder of childhood. The symmetrical necrotic lesions in the basal ganglia and/or brainstem which appear as hyperintense lesions on T2-weighted MRI is characteristic and one of the essential diagnostic criteria. Recognising this MR imaging pattern in a child with neurological problems should prompt the clinician to investigate for Leigh syndrome. We present here two cases of Leigh syndrome due to different biochemical/genetic defects, and discuss the subtle differences in their MR neuroimaging features.

Nicholas John Unsworth

<h3>BACKGROUND AND PURPOSE:</h3> Neurologic complications in infective endocarditis are frequent and affect patient prognosis negatively. Additionally, detection of asymptomatic lesions by MR imaging could help early management of this condition....

Combined Pituitary Hormone Deficiency and PROP-1 Mutation in Two Siblings: A Distinct MR Imaging Pattern of Pituitary Enlargement

Mutations of the PROP-1 gene are the most frequent genetic defect in patients with combined pituitary hormone insufficiency. We present the cases of 2 siblings with PROP-1 mutations whom we observed longitudinally. Their initial pituitary MR imaging examinations showed identical findings: an enlarged adenohypophysis, with striking hypointensity on T2-weighted images and slight hyperintensity on T1-weighted images. In one of the children, the follow-up MR imaging obtained 3 years after hormonal replacement revealed a decrease in the size of the anterior pituitary lobe.