Persistent pulmonary hypertension in neonates with perinatal asphyxia and therapeutic hypothermia: a frequent and perilous combination.

OBJECTIVES: (1) To investigate whether neonates with perinatal asphyxia and therapeutic hypothermia more often developed PPHN compared to a control group with perinatal asphyxia not treated with hypothermia; (2) To identify risk factors for severe PPHN during hypothermia and evaluate short-term outcome. METHODS: This single-center retrospective cohort study included (near-)term neonates with perinatal asphyxia admitted between 2004 and 2016. Neonates with perinatal asphyxia and hypothermia were compared to a historical control group without hypothermia. Primary outcome was PPHN, defined as severe hypoxemia requiring mechanical ventilation and inhaled nitric oxide, confirmed by echocardiography. Short-term adverse outcome was defined as mortality within one month and/or severe brain injury on MRI. RESULTS: Incidence of PPHN was 23% (26/114) in the hypothermia group and 11% (8/70) in controls. In multivariate analysis, PPHN was 2.5 times more common among neonates with hypothermia. Neonates developing PPHN during hypothermia often had higher fraction of inspired oxygen at baseline. PPHN was not associated with a higher risk of severe brain injury. However, early mortality was higher and three infants died due to severe refractory PPHN during hypothermia. CONCLUSIONS: In this study PPHN occurred more often since the introduction of therapeutic hypothermia. This was usually reversible and did not lead to overall increased adverse outcome. However, in individual cases with PPHN deterioration occurred rapidly. In such cases the benefits of hypothermia should be weighed against the risk of a complicated, fatal course.

Combining advanced MRI and EEG techniques better explains long-term motor outcome after very preterm birth.

BACKGROUND: Preterm born children are at high risk for adverse motor neurodevelopment. The aim of this study was to establish the relationship between motor outcome and advanced magnetic resonance imaging (MRI) and electroencephalography (EEG) measures. METHODS: In a prospective cohort study of 64 very preterm born children, the motor outcome was assessed at 9.83 (SD 0.70) years. Volumetric MRI, diffusion tensor imaging (DTI), and EEG were acquired at 10.85 (SD 0.49) years. We investigated associations between motor outcome and brain volumes (white matter, deep gray matter, cerebellum, and ventricles), white matter integrity (fractional anisotropy and mean, axial and radial diffusivity), and brain activity (upper alpha (A2) functional connectivity and relative A2 power). The independence of associations with motor outcome was investigated with a final model. For each technique, the measure with the strongest association was selected to avoid multicollinearity. RESULTS: Ventricular volume, radial diffusivity, mean diffusivity, relative A2 power, and A2 functional connectivity were significantly correlated to motor outcome. The final model showed that ventricular volume and relative A2 power were independently associated with motor outcome (B = -9.42 × 10-5, p = 0.027 and B = 28.9, p = 0.007, respectively). CONCLUSIONS: This study suggests that a lasting interplay exists between brain structure and function that might underlie motor outcome at school age. IMPACT: This is the first study that investigates the relationships between motor outcome and brain volumes, DTI, and brain function in preterm born children at school age. Ventricular volume and relative upper alpha power on EEG have an independent relation with motor outcome in preterm born children at school age. This suggests that there is a lasting interplay between structure and function that underlies adverse motor outcome.

The degree of prematurity affects functional brain activity in preterm born children at school-age: An EEG study.

Prematurely born children are at higher risk for long-term adverse motor and cognitive outcomes. The aim of this paper was to compare quantitative measures derived from electroencephalography (EEG) between extremely (EP) and very prematurely (VP) born children at 9-10 years of age. Fifty-five children born <32 weeks' of gestation underwent EEG at 9-10 years of age and were assessed for motor development and cognitive outcome. Relative frequency power and functional connectivity, as measured by the Phase Lag Index (PLI), were calculated for all frequency bands. Per subject, power spectrum and functional connectivity results were averaged over all channels and pairwise PLI values to explore differences in global frequency power and functional connectivity between EP and VP children. Brain networks were constructed for the upper alpha frequency band using the Minimum Spanning Tree method and were compared between EP and VP children. In addition, the relationships between upper alpha quantitative EEG results and cognitive and motor outcomes were investigated. Relative power and functional connectivity were significantly higher in VP than EP children in the upper alpha frequency band, and VP children had more integrated networks. A strong positive correlation was found between relative upper alpha power and motor outcome whilst controlling for gestational age, age during EEG recording, and gender (ρ = 0.493, p = 0.004). These results suggest that 9-10 years after birth, the effects of the degree of prematurity can be observed in terms of alterations in functional brain activity and that motor deficits are associated with decreases in relative upper alpha power.

Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants.

BACKGROUND: Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain. OBJECTIVE: The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age <32 weeks) detected by T2*-W gradient echo MRI to white matter injury and neurodevelopmental outcome at 2 years. MATERIALS AND METHODS: In 101 preterm infants, presence and location of hemosiderin were assessed on T2*-W gradient echo MRI performed around term-equivalent age (range: 40-60 weeks). White matter injury was defined as the presence of >6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome. RESULTS: In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P < 0.001) and cysts (P < 0.001) at term-equivalent age, and with a lower psychomotor development index (PDI) (P=0.02) at 2 years. After correcting for known confounders (gestational age, gender, intrauterine growth retardation and white matter injury), the correlation with PDI was no longer significant. CONCLUSION: The clinical importance of detecting small hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome.

Small cerebellar hemorrhage in preterm infants: perinatal and postnatal factors and outcome.

The objective of the study is to determine perinatal and postnatal factors that may affect the occurrence of small cerebellar hemorrhage (CBH) and to evaluate the effect of small CBH on neurodevelopmental outcome in very preterm infants. This prospective study in an unselected cohort of very preterm infants was approved by the medical ethics committee, and informed parental consent was obtained. Presence of small CBH (<4 mm) was assessed with magnetic resonance imaging around term equivalent age in 108 preterm infants (<32 weeks gestation). We compared infants with and without small CBH for perinatal and postnatal factors, supratentorial brain injury, and for neurodevelopmental outcome at 2 years corrected age. Follow-up consisted of a neurological examination, mental and developmental assessment (Bayley Scales of Infant Development), and behavior checklist. Univariate and multivariate logistic regression analyses were performed to examine the relationships between variables. Small CBH was diagnosed in 16/108 very preterm infants. Univariate analyses identified gestational age, high-frequency oscillation (HFO) ventilation, and grade 3-4 intraventricular hemorrhage (IVH) as factors associated with small CBH. HFO ventilation and severe IVH were independent predictors of small CBH. We found no association between small CBH and neurodevelopmental outcome at 2 years of age. Small CBH is a frequent finding in preterm infants. These hemorrhages are independently associated with HFO ventilation and severe supratentorial hemorrhage and seem to have a favorable short-term prognosis.

Tractography of white-matter tracts in very preterm infants: a 2-year follow-up study.

AIM: The aim of this study was to determine whether tractography of white-matter tracts can independently predict neurodevelopmental outcome in very preterm infants. METHOD: Out of 84 very preterm infants admitted to a neonatal intensive care unit, 64 (41 males, 23 females; median gestational age 29.1 weeks [range 25.6-31.9]; birthweight 1163 g [range 585-1960]) underwent follow-up at 2 years. Diffusion tensor imaging (DTI) values obtained around term were associated with a neurological examination and mental and psychomotor developmental index scores at 2 years based on the Bayley Scales of Infant Development (version 3). Univariate and logistic regression analyses tested for associations between DTI values and follow-up parameters. Cut-off values predicting motor delay and cerebral palsy (CP) were determined for fractional anisotropy, apparent diffusion coefficient (ADC), and fibre lengths. RESULTS: Infants with psychomotor delay and CP had significantly lower fractional anisotropy values (p=0.002, p=0.04 respectively) and shorter fibre lengths (p=0.02, p=0.02 respectively) of the posterior limb of the internal capsule. Infants with psychomotor delay also had significantly higher ADC values (p=0.03) and shorter fibre lengths (p=0.002) of the callosal splenium. Fractional anisotropy values of the posterior limb of the internal capsule independently predicted motor delay and CP, with sensitivity between 80 and 100% and specificity between 66 and 69%. ADC values of the splenium independently predicted motor delay with sensitivity of 100% and specificity of 65%. INTERPRETATION: Diffusion tensor imaging tractography at term-equivalent age independently predicts psychomotor delay at 2 years of age in preterm infants.

Ultrasound detection of posterior fossa abnormalities in full-term neonates.

Routine cranial ultrasonography, using the anterior fontanelle as acoustic window enables visualization of the supratentorial brain structures in neonates and young infants. The mastoid fontanelle enables a better view of the infratentorial structures, especially cerebellar hemorrhage in preterm infants. Reports on the usefulness and reliability of cranial ultrasonography using the mastoid fontanelle approach for the detection of posterior fossa abnormalities, focusing only on full-term neonates are limited. This article describes the technique of mastoid fontanelle ultrasonography in full-term neonates and the features of posterior fossa abnormalities that may be encountered in various neonatal disorders and conditions, combined with subsequent MRI in the same patients. Cranial ultrasound through the mastoid fontanelle plays a pivotal role in the early detection of posterior fossa pathology and selection of neonates with an indication for MRI.

Clinical implications of MR imaging findings in the white matter in very preterm infants: a 2-year follow-up study.

PURPOSE: To explore the association between diffuse excessive high signal intensity (DEHSI), punctate white matter (WM) lesions, and ventricular dilatation around term-equivalent age (TEA) and at clinical follow-up at 2 years in very preterm infants and the effect on neurodevelopment. MATERIALS AND METHODS: Ethical approval for this prospective study was given by the institutional review board, and informed parental consent was obtained. An unselected cohort of 110 preterm infants (gestational age, < 32 weeks) was imaged around or after TEA. Clinical follow-up was performed at a corrected age of 2 years and consisted of a neurologic examination and a mental and developmental assessment (Bayley Scales of Infant Development). Univariate analyses and logistic and linear regression were performed to examine the relationships between variables. RESULTS: DEHSI was found in 58 of 65 (89%) infants imaged around TEA. DEHSI was never detected in infants imaged after postmenstrual age of 50 weeks and showed no association with neurodevelopmental outcome. Punctate WM lesions and ventricular dilatation were significantly associated with mental (P = .02 for punctate WM lesions) and psychomotor developmental delay (P < .001 and P = .03, respectively), motor delay (P = .002 and P = .02, respectively), and cerebral palsy (P = .01 and P = .03, respectively). CONCLUSION: Because of its high incidence in preterm infants around TEA, its absence after a postmenstrual age of 50 weeks, and its association with normal neurologic outcome at a corrected age of 2 years, DEHSI should not be considered part of the spectrum of WM injury, but rather a prematurity-related developmental phenomenon.

Ultrasound detection of white matter injury in very preterm neonates: practical implications.

AIM: Diffuse white matter injury is not well detected by cranial ultrasonography (CUS). The aim of this study was twofold: (1) to assess in very preterm neonates the predictive values of individual CUS abnormalities for white matter injury on MRI and neurological outcome; (2) to develop a strategy optimizing CUS detection of white matter injury. METHOD: Very preterm neonates (n=67; 44 males, 23 females) underwent serial CUS and single MRI. Predictive values of CUS findings for a white matter classification on MRI, individual MRI findings, and neurological outcome at 2 years corrected age were calculated. The effects of timing and frequency of CUS were evaluated. RESULTS: Periventricular echodensities (PVEs) predicted abnormal white matter on MRI, but absence of PVEs did not predict absence of white matter changes. Peri- and intraventricular haemorrhage (P/IVH) was highly predictive of abnormal white matter on MRI. Frequency and timing of CUS did not influence predictive values. P/IVH and abnormal ventricular size/shape were reasonably predictive of unfavourable outcome, whereas absence of CUS abnormalities predicted a favorable outcome. INTERPRETATION: (1) If PVEs are present, there is a significant chance of abnormal white matter on MRI. (2) Increasing frequency of CUS does not increase its diagnostic performance for white matter injury. (3) P/IVH is highly predictive of abnormal white matter on MRI and reasonably predictive of unfavourable outcome. (4) Absence of PVEs and P/IVH on CUS does not guarantee normal white matter, but predicts a favourable outcome.

Tractography of developing white matter of the internal capsule and corpus callosum in very preterm infants.

OBJECTIVES: To investigate in preterm infants associations between Diffusion Tensor Imaging (DTI) parameters of the posterior limb of the internal capsule (PLIC) and corpus callosum (CC) and age, white matter (WM) injury and clinical factors. METHODS: In 84 preterm infants DTI was performed between 40-62 weeks postmenstrual age on 3 T MR. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) values and fibre lengths through the PLIC and the genu and splenium were determined. WM injury was categorised as normal/mildly, moderately and severely abnormal. Associations between DTI parameters and age, WM injury and clinical factors were analysed. RESULTS: A positive association existed between FA and age at imaging for fibres through the PLIC (r = 0.48 p < 0.001) and splenium (r = 0.24 p < 0.01). A negative association existed between ADC and age at imaging for fibres through the PLIC (r = -0.65 p < 0.001), splenium (r = -0.35 p < 0.001) and genu (r = -0.53 p < 0.001). No association was found between DTI parameters and gestational age, degree of WM injury or categorical clinical factors. CONCLUSIONS: These results indicate that in our cohort of very preterm infants, at this young age, the development of the PLIC and CC is ongoing and independent of the degree of prematurity or WM injury.

Is sequential cranial ultrasound reliable for detection of white matter injury in very preterm infants?

INTRODUCTION: Cranial ultrasound (cUS) may not be reliable for detection of diffuse white matter (WM) injury. Our aim was to assess in very preterm infants the reliability of a classification system for WM injury on sequential cUS throughout the neonatal period, using magnetic resonance imaging (MRI) as reference standard. METHODS: In 110 very preterm infants (gestational age <32 weeks), serial cUS during admission (median 8, range 4-22) and again around term equivalent age (TEA) and a single MRI around TEA were performed. cUS during admission were assessed for presence of WM changes, and contemporaneous cUS and MRI around TEA additionally for abnormality of lateral ventricles. Sequential cUS (from birth up to TEA) and MRI were classified as normal/mildly abnormal, moderately abnormal, or severely abnormal, based on a combination of findings of the WM and lateral ventricles. Predictive values of the cUS classification were calculated. RESULTS: Sequential cUS were classified as normal/mildly abnormal, moderately abnormal, and severely abnormal in, respectively, 22%, 65%, and 13% of infants and MRI in, respectively, 30%, 52%, and 18%. The positive predictive value of the cUS classification for the MRI classification was high for severely abnormal WM (0.79) but lower for normal/mildly abnormal (0.67) and moderately abnormal (0.64) WM. CONCLUSION: Sequential cUS during the neonatal period detects severely abnormal WM in very preterm infants but is less reliable for mildly and moderately abnormal WM. MRI around TEA seems needed to reliably detect WM injury in very preterm infants.

Cerebellar injury in preterm infants: incidence and findings on US and MR images.

PURPOSE: To investigate the incidence and characteristics of cerebellar injury in a cohort of very preterm infants by using the mastoid fontanelle (MF) and posterior fontanelle (PF) approach in addition to routine cranial ultrasonography (US) through the anterior fontanelle (AF), with magnetic resonance (MR) imaging as the reference standard. MATERIALS AND METHODS: The institutional review board approved this prospective study and informed consent was obtained. A cohort of 77 preterm infants (< 32 weeks) was examined with serial cranial US throughout the neonatal period by using the AF, PF, and MF views. MR imaging was performed around term-equivalent age in 59 of 77 infants. Sensitivity, specificity, positive predictive value, and negative predictive value of routine cranial US and cranial US with additional views were calculated. RESULTS: At cranial US performed through the MF, seven (9%) of 77 infants were identified to have posterior fossa hemorrhage. In only two of seven infants, the lesions were seen on routine AF views. The PF approach did not increase the detection rate of posterior fossa hemorrhage. MR images confirmed cranial US findings in all cases. MR images showed punctate hemorrhage in the cerebellum in six infants with normal cranial US findings. Among the 59 infants examined with both cranial US and MR imaging, cerebellar injury was diagnosed in 11 (19%). CONCLUSION: Cerebellar injury is a frequent finding in very preterm infants. Cranial US through the MF can demonstrate injury missed by using the routine AF approach. Punctate hemorrhagic lesions may remain undetected even when the MF approach is used; the prognostic implications of these smaller lesions need further attention.

Surgery for large vestibular schwannoma: residual tumor and outcome.

OBJECTIVE: To evaluate clinical outcome with regard to the amount of residual tumor after surgery for large vestibular schwannoma. PATIENTS: Between January 2000 and December 2005, 51 large vestibular schwannoma tumors with extrameatal diameter of 2.6 cm or greater (mean, 32 mm; median, 30 mm; range, 26-50 mm) were operated using the translabyrinthine approach. The extent of the resection was intraoperatively estimated as complete, near, and subtotal. The amount of residual tumor was measured, and the shape and localization was scored on gadolinium-enhanced magnetic resonance imaging (MRI). Correlation between intraoperative and MRI assessment was performed using the Fisher's exact test. Potential growth of residual tumor was documented with frequent MRI follow-up. Postoperative facial nerve function was classified according to the House-Brackmann classification. RESULTS: Complete resection was performed in 26% of the patients, near-total resection in 58%, and subtotal resection in 16%. Magnetic resonance imaging showed residual tumor in 46% of patients (mean, 16.7 mm; SD, +/-8, range, 5-36 mm). Postoperative facial nerve function was House-Brackmann Grades I to II in 78% of the patients. The intraoperative assessment of near-total resection did not correlate with postoperative MRI (p = 0.25). Postoperative MRI showed either no residual tumor or residue that should actually have been classified as a subtotal resection. After a follow-up of 4 years (49 mo; mean, 48 mo), 94% of patients did not show changes on MRI. CONCLUSION: Tumor control with good facial nerve function could be obtained in most patients. Intraoperative assessment did not correlate with the amount of residual tumor on postoperative MRI. Objective documentation with postoperative MRI to measure the extent of removal is therefore mandatory.

Brain imaging findings in very preterm infants throughout the neonatal period: part I. Incidences and evolution of lesions, comparison between ultrasound and MRI.

This study describes the incidence and evolution of brain imaging findings in very preterm infants (GA<32 weeks), assessed with sequential cranial ultrasound (cUS) throughout the neonatal period and MRI around term age. The accuracy of both tools is compared for findings obtained around term. Periventricular echodensities and intraventricular haemorrhage were the most frequent cUS findings during admission. Frequent findings on both cUS and MRI around term included ventricular dilatation, widened extracerebral spaces, and decreased cortical complexity. MRI additionally showed punctate white matter lesions and diffuse and excessive high signal intensity, but did not depict lenticulostriate vasculopathy and calcifications, and was less reliable for germinolytic and plexus cysts. cUS detected most abnormalities that have been associated with abnormal neurodevelopmental outcome.

Brain imaging findings in very preterm infants throughout the neonatal period: part II. Relation with perinatal clinical data.

This study describes the relation between frequent and clinically relevant brain imaging findings in very preterm infants (GA<32 weeks), assessed with sequential cranial ultrasonography throughout the neonatal period and MRI around term age, and several potential perinatal risk factors. For ultrasound findings during admission the following independent risk factors were identified: male gender for periventricular echodensities and intraventricular haemorrhage, postnatal corticosteroid treatment for cystic white matter lesions, and lower gestational age for post-haemorrhagic ventricular dilatation. For MRI findings around term age, including punctate white matter lesions, ventricular dilatation, decreased cortical complexity, and diffuse and excessive high signal intensity, no independent risk factors were found. In very preterm infants, the risk factors for frequently found changes on cranial ultrasound have largely remained unchanged over the last decades, while no risk factors could be identified for subtle and diffuse white matter injury as seen on MRI around term age.

Magnetic resonance imaging of the brain in newborn infants: practical aspects.

Magnetic Resonance Imaging is becoming more widely available and increasingly important for imaging the neonatal brain. In newborn infants it poses challenges regarding patient preparation, safety, optimal timing, and sequence optimization. These issues are addressed in this paper and indications for performing neonatal Magnetic Resonance Imaging are presented.

Volumetrical measurements in vestibular schwannoma, the influence of slice thickness and patient's repositioning.

OBJECTIVE: Conservative treatment in vestibular schwannomas is mainly dependent on optimal tumor size determination. The first objective of this study was to establish interobserver and intraobserver variability and the accuracy and reproducibility of three different measurement methods: one bidimensional and two volumetrical. The second objective was to evaluate the influence of the use of different magnetic resonance imaging (MRI) slice thickness and the influence of patient's repositioning on the measurements' outcome. STUDY DESIGN: Two consecutive studies have been prospectively performed, both mainly concerning volumetrical measurements. SETTING: Both studies were performed in a tertiary academic, multidisciplinary center. PATIENTS: In the first study, 19 patients were included between March 1996 and May 2002, with a total of 52 scans. The second study comprised 14 patients. All patients in the first study had at least two MRI examinations performed according to a standard protocol (T1-weighted gadolinium-enhanced, slice thickness of 3 mm, and interslice gap of 0.3 mm). The population in the second study underwent a conservative wait and scan (W&S) treatment. METHODS: Both studies are discussed separately. In the first study, all scans were measured by four investigators, two of whom performed the measurements twice using three different methods. The first method concerns a manually performed bidimensional surface measurement along the petrous pyramid. The second method concerns a semiautomatic volumetrical measurement on a computer, relying on contour detection, and the last method concerns a fully automatic volume reconstruction also performed on a computer using different gray shade scales. All 14 patients included in the second study underwent three magnetic examinations. Three different T1-weighted gadolinium-enhanced sequences were used: the first using a slice thickness of 1 mm, the second again with 1-mm slice thickness but after having repositioned the patient. In the third sequence, a slice thickness of 3 mm was used. All scans were measured by two investigators using the three different methods, as described previously. RESULTS: The manual surface method shows large intraobserver variability, and its reproducibility is significantly lower compared with volume measurements. Because of a relatively large systematic error in small tumors, sensitivity of growth detection is low. Both volumetrical methods are hardly interobserver- and intraobserver-dependent, and the gray shade method turned out to be the most accurate. Radiologic progression is only significant at a volume increase of at least 50%. The influence of patient repositioning is negligible, whereas the use of 1-mm slice thickness seems to be superior to a 3-mm slice thickness. CONCLUSION: The volumetrical gray shade method is the most accurate method to detect early tumor progression. As tumor increase of at least 50% is needed to be able to speak of statistically significant tumor growth, the absence of radiologic progression does not mean that there is no tumor growth. Repositioning of the patient has no influence on the measurements' outcome, whereas for optimal magnetic resonance imaging examinations, a 1-mm slice thickness protocol seems to be superior.

The value of MR angiography techniques in the detection of head and neck paragangliomas.

OBJECTIVE: The objective of this study was to compare three-dimensional phase-contrast angiography (3D PCA), 2D time-of-flight (2D TOF), and 3D TOF magnetic resonance (MR) angiography and a proton density weighted technique in terms of their ability to detect head and neck paragangliomas. MATERIALS AND METHODS: 14 patients with 29 paragangliomas were examined at 1.5 T. Three MR angiography sequences (3D PCA, 2D TOF, and multi-slab 3D TOF) and a proton density (PD) weighted sequence were reviewed by four neuroradiologists. The gold standard was digital subtraction angiography. Presence of tumor was assessed in five grades of confidence. Sensitivity and specificity were calculated after dichotomizing the results. Data was analyzed using the logistic regression method. RESULTS: Mean sensitivity and specificity for the four observers were for PD: 72%/97%, for 3D PCA: 75%/90%, for 2D TOF: 66%/93%, and for 3D TOF: 90%/92%. Sensitivity was significantly better for 3D TOF MRA (P < 0.001). No substantial between-observer variation for tumor detection was present. CONCLUSION: Our results demonstrate that, using 3D TOF MRA, paragangliomas in the head and neck region can be detected with high sensitivity and specificity. Further investigation is necessary to judge the value of 3D TOF MR angiography against fat suppressed contrast enhanced T1 weighted and fat suppressed T2 weighted MR sequences to find the optimal imaging sequence for paragangliomas.