Arterial-spin labeling MRI identifies residual cerebral arteriovenous malformation following stereotactic radiosurgery treatment.

BACKGROUND AND PURPOSE: Brain arteriovenous malformation (AVM) treatment by stereotactic radiosurgery (SRS) is effective, but AVM obliteration following SRS may take two years or longer. MRI with arterial-spin labeling (ASL) may detect brain AVMs with high sensitivity. We determined whether brain MRI with ASL may accurately detect residual AVM following SRS treatment. MATERIALS AND METHODS: We performed a retrospective cohort study of patients who underwent brain AVM evaluation by DSA between June 2010 and June 2015. Inclusion criteria were: (1) AVM treatment by SRS, (2) follow-up MRI with ASL at least 30 months after SRS, (3) DSA within 3 months of the follow-up MRI with ASL, and (4) no intervening AVM treatment between the MRI and DSA. Four neuroradiologists blindly and independently reviewed follow-up MRIs. Primary outcome measure was residual AVM indicated by abnormal venous ASL signal. RESULTS: 15 patients (12 females, mean age 29 years) met inclusion criteria. There were three posterior fossa AVMs and 12 supratentorial AVMs. Spetzler-Martin (SM) Grades were: SM1 (8%), SM2 (33%), SM3 (17%), SM4 (25%), and SM5 (17%). DSA demonstrated residual AVM in 10 patients. The pooled sensitivity, specificity, positive predictive value, and negative predictive value of venous ASL signal for predicting residual AVM were 100% (95% CI: 0.9-1.0), 95% (95% CI: 0.7-1.0), 98% (95% CI: 0.9-1.0), and 100% (95% CI: 0.8-1.0), respectively. High inter-reader agreement as found by Fleiss' Kappa analysis (k = 0.92; 95% CI: 0.8-1.0; P < 0.0001). CONCLUSIONS: ASL is highly sensitive and specific in the detection of residual cerebral AVM following SRS treatment.

Findings and patterns on MRI and MR spectroscopy in neonates after therapeutic hypothermia for hypoxic ischemic encephalopathy treatment.

OBJECTIVES: The purpose of this study is to describe the findings and patterns of injury on magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) after whole-body hypothermia treatment for neonatal hypoxic ischemic encephalopathy. METHODS: A retrospective review of consecutive term neonates treated with whole-body hypothermia was performed. Data recorded included demographics and MRI and MRS findings, and day of life (DOL) studies were performed. Injury patterns were classified on MRI as deep, cortical, mixed, or diffuse. The relative apparent diffusion coefficient (rADC) was plotted against DOL scanned and the presence of lactate was recorded. RESULTS: MRI was performed in 44 infants, 34 of whom also underwent MRS. MRI was abnormal in 32% of neonates, 29.5% of whom were imaged at DOL 4 to 8. rADC values were lowest in neonates scanned on DOL 4 and 5 and remained low up to DOL 8. The deep brain nuclei were involved in hypoxic ischemic encephalopathy in 93% of neonates with abnormal MRIs and lactate was identified on MRS in 18% of neonates between DOL 4 and 8. CONCLUSIONS: MRI performed after therapeutic cooling was abnormal in 29.5% of neonates scanned on DOL 4 to 8. Deep nuclear injury was identified in 93% of neonates. Lactate was present on MRS in 18% of neonates, and rADC values were most reduced on MRI between DOL 4 and 8.

Borderline low conus medullaris on infant lumbar sonography: what is the clinical outcome and the role of neuroimaging follow-up?

BACKGROUND: Isolated borderline low conus medullaris is a frequent finding on screening lumbar sonography of unknown significance that often prompts further imaging and clinical follow-up. OBJECTIVE: To determine the clinical outcome and utility of follow-up neuroimaging in infants with isolated borderline low conus on lumbar sonography. MATERIALS AND METHODS: We reviewed 748 consecutive spinal sonograms identifying infants with conus terminating between L2-L3 disc space and mid-L3 level without other findings of tethered cord. We excluded infants with conditions associated with developmental delay and those who passed away, and compared the age of gross motor milestone achievement to normal ranges. Follow-up imaging was reviewed. RESULTS: Isolated borderline low conus was found in 90 of 748 infants (12%) on sonography. Seventy of those infants met inclusion criteria. Follow-up imaging in 11 children (10 MRI, 1 sonogram), showed change in conus position to "normal" level in 10, no change in 1, and no new findings within lumbar spine. Clinical follow-up was available in 50 of 70 (71%) children meeting inclusion criteria, with normal motor milestones met in all 50 children. CONCLUSION: Isolated borderline low conus is a common finding in infants who meet normal developmental milestones suggesting that follow-up evaluation has little utility and is likely unwarranted.