Prospective Comparison of T1-SPACE and MPRAGE for the Identification of Intrinsic T1 Hyperintensity in Patients with Intracranial Melanoma Metastases.

BACKGROUND AND PURPOSE: Volumetric TSE (3D-TSE) techniques are increasingly replacing volumetric magnetization-prepared gradient recalled-echo (3D-GRE) sequences due to improved metastasis detection. In addition to providing a baseline for assessing postcontrast enhancement, precontrast T1WI also identifies intrinsic T1 hyperintensity, for example, reflecting melanin or blood products. The ability of precontrast 3D-TSE to demonstrate intrinsic T1 hyperintensity is not clear from the literature; thus, this study compares precontrast 3D-TSE and 3D-GRE sequences for identifying intrinsic T1 hyperintensity in patients with metastatic melanoma. MATERIALS AND METHODS: Patients with metastatic melanoma and previously reported intrinsic T1 hyperintensity were identified. MRIs were performed at 3T including both 3D-GRE (MPRAGE) and 3D-TSE T1 sampling perfection with application-optimized contrasts by using different flip angle evolution (T1-SPACE) sequences precontrast. Axial 1-mm slices of both T1WI sequences were independently reviewed by 2 neuroradiologists, comparing the conspicuity of each lesion between the 2 sequences according to a 5-point scale and assessing whether the intrinsic T1 hyperintensity was attributable to melanin, blood products, or both. RESULTS: Twenty examinations were performed, with a total of 214 lesions demonstrating intrinsic T1 hyperintensity. Both readers found that intrinsic T1 hyperintensity was less conspicuous with T1-SPACE compared with MPRAGE for most lesions assessed (81.8%, averaged across both readers), including for lesions with intrinsic T1 hyperintensity attributable to melanin and blood products. Intrinsic T1 hyperintensity was rarely more conspicuous on T1-SPACE (1.4%). CONCLUSIONS: Precontrast intrinsic T1 hyperintensity is more conspicuous with MPRAGE than T1-SPACE. In patients with metastatic melanoma, 3D-GRE should be preferred as the precontrast T1WI sequence when both 3D-TSE and 3D-GRE are performed postcontrast and when not administering IV contrast.

Improving the diagnosis of radiation necrosis after stereotactic radiosurgery to intracranial metastases with conventional MRI features: a case series.

BACKGROUND: The distinction between true disease progression and radiation necrosis after stereotactic radiosurgery to intracranial metastases is a common, but challenging, clinical scenario. Improvements in systemic therapies are increasing the importance of this distinction. A variety of imaging techniques have been investigated, but the value of any individual technique is limited. CASE PRESENTATION: Assessment should extend beyond simply the appearances of the lesion at a given timepoint, but also consider local anatomy and lesion evolution. Firstly, enlargement of a metastasis is affected by local anatomical boundaries, such as the dural reflections or cerebrospinal fluid spaces. In contrast, the radiation dose administered with stereotactic radiosurgery does not respect these anatomical boundaries and is largely concentric around the treated lesion. Therefore, new, non-contiguous enhancement across such a boundary can be confidently attributed to radiation necrosis. Secondly, the dynamic nature of radiation necrosis may result in a change in lesion shape, with different portions of the lesion simultaneously enlarging and regressing. Regression of part of a lesion indicates radiation necrosis, even if the overall lesion enlarges. This case series describes these two features and provides illustrative clinical examples in which these features allowed a confident diagnosis of radiation necrosis. CONCLUSIONS: The distinction between true disease progression and radiation necrosis should extend beyond just the appearances of the lesion. More nuanced interpretation incorporating a relationship to anatomical boundaries and a change in shape can improve accurate diagnosis of radiation necrosis.

The incidence and significance of multicentric noncontrast-enhancing lesions distant from a histologically-proven glioblastoma.

Improvements in imaging are increasing the detection of multiple lesions in the setting of glioblastoma. Occasionally distant non-enhancing lesions may be identified which have the appearances of a multicentric low-grade glioma. We aimed to determine the incidence, prognostic significance and diagnostic value of this appearance in new glioblastoma patients. Pre-operative MRIs of patients with a new diagnosis of glioblastoma were reviewed to identify multicentric non-enhancing lesions, defined as areas of FLAIR hyperintensity and mass effect, without post-contrast enhancement, separate from the histologically-proven glioblastoma. Patient survival was compared to glioblastoma patients without these appearances, and follow-up imaging was reviewed. Nine of 151 patients (6 %) had multicentric non-enhancing lesions. Their median survival of 183 days was significantly worse than the 278 days for patients without multicentric nonenhancing lesions (p = 0.025). Follow-up MRIs were performed in four patients. In one patient, there were several additional lesions, one of which developed evidence of necrosis within 22 days of presentation. In the other three patients, the multicentric lesions developed enhancement and evidence of necrosis within 1 year, and became confluent on FLAIR with the dominant lesion. The appearance of a multicentric non-enhancing lesion is an uncommon finding in glioblastoma, but a poor prognostic feature. These lesions progress faster than expected for a low-grade glioma and are thus likely to represent more advanced lesions than their appearances suggest. Confluence with the dominant lesion developing with time suggests that the tumor is more extensive than appreciated on imaging.

Large anterior temporal Virchow-Robin spaces: unique MR imaging features.

INTRODUCTION: Large Virchow-Robin (VR) spaces may mimic cystic tumor. The anterior temporal subcortical white matter is a recently described preferential location, with only 18 reported cases. Our aim was to identify unique MR features that could increase prospective diagnostic confidence. METHODS: Thirty-nine cases were identified between November 2003 and February 2014. Demographic, clinical data and the initial radiological report were retrospectively reviewed. Two neuroradiologists reviewed all MR imaging; a neuropathologist reviewed histological data. RESULTS: Median age was 58 years (range 24-86 years); the majority (69 %) was female. There were no clinical symptoms that could be directly referable to the lesion. Two thirds were considered to be VR spaces on the initial radiological report. Mean maximal size was 9 mm (range 5-17 mm); majority (79 %) had perilesional T2 or fluid-attenuated inversion recovery (FLAIR) hyperintensity. The following were identified as potential unique MR features: focal cortical distortion by an adjacent branch of the middle cerebral artery (92 %), smaller adjacent VR spaces (26 %), and a contiguous cerebrospinal fluid (CSF) intensity tract (21 %). Surgery was performed in three asymptomatic patients; histopathology confirmed VR spaces. Unique MR features were retrospectively identified in all three patients. CONCLUSION: Large anterior temporal lobe VR spaces commonly demonstrate perilesional T2 or FLAIR signal and can be misdiagnosed as cystic tumor. Potential unique MR features that could increase prospective diagnostic confidence include focal cortical distortion by an adjacent branch of the middle cerebral artery, smaller adjacent VR spaces, and a contiguous CSF intensity tract.

Hippocampal calcification prevalence at CT: a retrospective review.

PURPOSE: To determine the prevalence of intrahippocampal calcification at brain computed tomography (CT), evaluate any association with calcification involving the intracranial arteries or lentiform nuclei, and assess the clinical importance of intrahippocampal calcification. MATERIALS AND METHODS: Study approval was obtained by the Southern Health Human Research Ethics Committee, which waived the requirement for informed consent because of the retrospective nature of the study. The presence of intrahippocampal calcification was assessed by four readers through retrospective review of 300 randomly selected nonenhanced brain CT scans. In addition, the presence of calcification involving the intracranial arteries and lentiform nuclei was assessed, and the clinical histories were reviewed in those patients with intrahippocampal calcifications and a matched control cohort without intrahippocampal calcification. Differences in proportion of patients with intrahippocampal calcifications across different age groups were assessed by using χ2 analysis. Interrater agreement and intrarater agreement were assessed by using κ analysis. RESULTS: Intrahippocampal calcification was demonstrated in 47 (15.7%) of 300 patients, and 47 (21.7%) of 217 patients older than 50 years of age. Its prevalence increased with age (P=.008). All patients with intrahippocampal calcification and the control cohort demonstrated calcification involving the intracranial arteries. Eleven (23.4%) of 47 patients with intrahippocampal calcification had calcification within the lentiform nuclei compared with 14 (29.8%) of 47 in the control cohort (P=.67). The anatomic distribution of intrahippocampal calcification was similar to that described in vascular fibrosis and calcification. CONCLUSION: The prevalence of intrahippocampal calcification appears to increase with age and is a relatively common finding in patients older than 50 years. It has a similar anatomic distribution to microscopic vascular fibrosis and calcification and likely reflects its latter stages.

Diagnostic yield of computed tomography of the brain in first episode psychosis.

INTRODUCTION: Brain computed tomography (CT) is inconsistently recommended worldwide in the investigative algorithm of patients presenting with first episode psychosis (FEP). The objective of this study is to investigate the clinical efficacy of brain CT in patients presenting with FEP without neurological signs in a major metropolitan teaching hospital. METHODS: The CT brain scan reports of 237 consecutive patients, for which the imaging requests or reports provided a history of FEP but no focal neurological signs, were retrospectively identified within a 6-year period in a 750-bed tertiary referral teaching hospital using the radiology information system text-search function (170 male, 67 female; mean age, 28.3 years). All reports were authored or approved by consultant radiologist. They were reviewed for the presence of any lesion that could cause psychosis and hence alter clinical management. Minor neuroradiological abnormalities were also noted. Hospital Ethics Committee registration and approval were obtained and patient informed consent was not required. RESULTS: No focal brain lesion potentially responsible for the psychosis or focal lesion requiring surgical intervention was identified in any patient. Findings unable to be directly linked to the psychosis such as evidence of small vessel ischaemic disease, arachnoid cysts, cerebral atrophy, and normal variants were present in 17.6% of patients (45 of 237 studies), none of which led to an alteration of clinical management. CONCLUSION: The results of this study postulate that brain CT should not be universally performed in the initial assessment of patients with first episode psychosis without neurological signs.

Susceptibility weighted imaging: a pictorial review.

Susceptibility weighted imaging (SWI) is a valuable technique in the evaluation of a wide variety of intracranial pathologies. SWI is a gradient echo sequence utilising both phase and magnitude data to achieve exquisite sensitivity to tissue magnetic susceptibility effects. Normal SWI appearances and common artefacts are illustrated. Examples of SWI in common intracranial pathologies such as subarachnoid, intraventricular and intraparenchymal haemorrhage, intra-axial and extra-axial tumours, pyogenic and non-pyogenic infections, trauma, neurodegenerative diseases and vascular disease including aneurysms, vascular malformations are illustrated and discussed. This pictorial essay will enable radiologists to recognise the normal, artefactual and common intracranial pathological appearances of SWI.

Women lose patella cartilage at a faster rate than men: a 4.5-year cohort study of subjects with knee OA.

OBJECTIVES: Patellofemoral knee osteoarthritis (OA) is a common disease, and a significant cause of knee pain, however few data have examined longitudinal change at the patellofemoral joint. The aim of this study was to examine factors affecting change in patella cartilage over a longer time period than previously examined. STUDY DESIGN: Longitudinal study of 77 subjects (58% female) with knee OA underwent magnetic resonance imaging (MRI), with a repeat MRI of the same knee obtained approximately 4.5 years later. MAIN OUTCOME MEASURES: Annual change in patella cartilage volume, and annual percentage change over 4.5 years. RESULTS: After adjusting for age, gender, BMI and patella bone volume at baseline, cartilage change was observed at the rate of 2.5% (95% confidence interval, 2.0, 3.0) per annum over 4.5 years. Cartilage was lost at a higher rate in women compared to men after accounting for age, BMI or bone volume at baseline (3.3% vs. 1.4%, respectively, p=0.03). Increased patella bone volume was associated with increased patella cartilage loss (p=0.02). No measures of radiographic severity of disease affected change in cartilage volume. CONCLUSIONS: The increased rate of cartilage loss in women may contribute to the increased prevalence of disease, although the underlying mechanism requires further study. Increased patella bone volume was also associated with increased patella cartilage loss. Whether this is due to biomechanical factors will need to be determined.

Comparison of 4 cm Z-axis and 16 cm Z-axis multidetector CT perfusion.

OBJECTIVE: The aim of the study was to compare 4 cm with 16 cm Z-axis coverage in the assessment of brain CT perfusion (CTP) using. 320 slice multidetector CT METHODS: A retrospective non-randomised review of CTP performed on MD320 CT between September 2008 and January 2009 was undertaken. Two experienced readers reviewed the studies along with the 4 cm and 16 cm Z-axis CTP image data set. The outcome parameters assessed were the extent of the original finding, any additional findings and a change of diagnosis. RESULTS: 14 out of 27 patients were found to have abnormal CTP (mean age 58.1 years, 9 male). The 16 cm Z-axis increased the accuracy of the infarct core in 78% and ischaemic penumbra quantification in 100% of the cases. It also diagnosed additional infarcts in the same vascular territory in 28% of cases and in a different vascular territory in 14%. CONCLUSIONS: The increased field of view with MD320 better defines the true extent of the infarct core and ischaemic penumbra. It also identified other areas of infarction that were not identified on the 4 cm Z-axis.

Peri-aortofemoral prosthesis urinoma: diagnosis by Tc-99m MAG3 SPECT/CT and differentiation from simultaneous hepatobiliary excretion.

A 75-year-old woman developed renal failure 1 week after elective aortobifemoral bypass surgery. Postoperative computed tomography showed right hydronephrosis. Tc-99m mercaptoacetyltriglycerine (MAG3) scintigraphy was performed to exclude renal obstruction or acute tubular necrosis. Planar MAG3 images demonstrated right hydronephrosis and unusual accumulation of tracer between the kidneys and the right upper quadrant of abdomen, with new areas of activity in the right lower quadrant on delayed images. SPECT/CT demonstrated MAG3 activity within fluid collections adjacent to the aorta and right iliac/inguinal arteries, consistent with a urine leak. The right upper quadrant activity represented MAG3 accumulation within the gallbladder.

Hyperintensity in the subarachnoid space on FLAIR MRI.

OBJECTIVE: The purposes of this essay are to illustrate the causes of FLAIR hyperintensity in the subarachnoid space and to outline the mechanisms of the findings. CONCLUSION: FLAIR subarachnoid space hyperintensity may be encountered with both pathological conditions and artifacts. Knowledge of these conditions and appearances coupled with any associated findings may suggest the cause of the FLAIR subarachnoid space hyperintensity. A diffuse distribution and a lack of ancillary findings often remain nonspecific and may require clinical correlation and CSF analysis.

Silent embolism in diagnostic cerebral angiography: detection with diffusion-weighted imaging.

Angiography has known and documented risks of neurological events. We prospectively studied 20 patients who underwent diagnostic cerebral angiographic examinations and diffusion-weighted MRI (DWI). Eighteen patients had DWI before and after their angiogram, whereas two patients had a DWI only after their angiogram (DWI was normal in both of these patients). No clinical neurological deficits were detected in any of our patients after angiography, but in three of 20 patients there was a new hyperintense signal abnormality found on DWI. Diffusion-weighted MRI provides an objective means of detecting both clinical and subclinical neurological events. Diffusion-weighted imaging might therefore provide an easier method of assessing complication rates in cerebral angiography by reducing the number of patients required for meaningful statistical analysis.

Extracerebral cavernous hemangioma of the cavernous sinus: diagnosis with MR imaging and labeled red cell blood pool scintigraphy.

We present the case of a 64-year-old man with a presumed diagnosis of extracerebral cavernous hemangioma involving the cavernous sinus. The diagnosis was made on the basis of labeled red cell blood pool scintigraphy findings in conjunction with those of MR imaging. This lesion was not altered in appearance at 6-year follow-up MR imaging. We also present the labeled red cell blood pool scintigraphy findings obtained in three other patients with similar-appearing cavernous sinus lesions at MR imaging who underwent subsequent biopsy; histologic findings confirmed chondrosarcoma, chordoma, and meningioma, respectively.

Isolated intrapetrous carotid canal atraumatic internal carotid artery dissection: MRI and digital subtraction angiography findings.

A case of spontaneous internal carotid artery (ICA) dissection confined to the intrapetrous carotid canal that was confirmed by angiography and magnetic resonance imaging is presented. Isolated dissection involving the intrapetrous ICA is rare; however, whenever arterial dissection is a consideration, specific review of imaging in this region is warranted.

Anomalous communication of external carotid and vertebral arteries with associated intracranial parenchymal arteriovenous malformation: magnetic resonance angiography and angiographic findings.

A case of anomalous communication of the external carotid and vertebral arteries via a pro-atlantal intersegmental artery (PIA) with an associated intracranial parenchymal arteriovenous malformation (AVM) is presented. The course of the PIA is displayed by both conventional catheter angiography and by MR angiography (MRA). To our knowledge, neither an associated intracranial parenchymal AVM nor depiction of this congenital anomaly on MRA has been previously described. We also briefly review the embryology and anatomy of this anomaly.

Rate of knee cartilage loss after partial meniscectomy.

OBJECTIVE: Surgical removal of the meniscus of the knee is thought to be a risk factor for later appearance of knee osteoarthritis (OA). We examined whether there is a difference in cartilage loss in those who undergo a partial meniscectomy compared to healthy controls. METHODS: Eight patients who underwent a meniscectomy (5 partial medial, 3 partial lateral) and 13 controls with normal knee radiographs and magnetic resonance imaging (MRI) had an MRI at baseline and at a mean 28.6 +/- 7.6 months followup. Articular cartilage volumes were determined by processing images acquired in the sagittal plane using T1 weighted fat saturation MRI on an independent work station. RESULTS: The mean +/- SD of percentage rates of cartilage loss from baseline volume were 4.1 +/- 2.8% per year for the meniscectomy subjects and -2.3 +/- 3.0% per year for the controls (difference 6.5% per year, 95% CI 3.7-9.3% per year; p < 0.001). After adjustment for age, body mass index, and sex the difference increased slightly to 6.9% per year (95% CI 3.4-10.3%; p = 0.001). CONCLUSION: This study suggests that significant rates of cartilage loss are seen in subjects post partial meniscectomy compared with healthy controls. This may be a useful model in which to examine therapies to prevent OA.