Raphael Calmon

Accuracy of perfusion MRI with high spatial but low temporal resolution to assess invasive breast cancer response to neoadjuvant chemotherapy: a retrospective study

BackgroundTo illustrate that Breast-MRI performed in high spatial resolution and low temporal resolution (1 minute) allows the measurement of kinetic parameters that can assess the final pathologic response to neoadjuvant chemotherapy in breast cancer.MethodsBreast-MRI was performed in 24 women before and after treatment. Eight series of 1.11 minute-duration were acquired with a sub-millimeter spatial resolution. Transfer constant (Ktrans) and leakage space (Ve) were calculated using measured and theoretical Arterial Input Function (AIF). Changes in kinetic parameters after treatment obtained with both AIFs were compared with final pathologic response graded in non-responder (< 50% therapeutic effect), partial-responder (> 50% therapeutic effect) and complete responder. Accuracies to identify non-responders were compared with receiver operating characteristic curves.ResultsWith measured-AIF, changes in kinetic parameters measured after treatment were in agreement with the final pathological response. Changes in Ve and Ktrans were significantly different between non-(N = 11), partial-(N = 7), and complete (N = 6) responders, (P = 0.0092 and P = 0.0398 respectively). A decrease in Ve of more than -72% and more than -84% for Ktrans resulted in 73% sensitivity for identifying non-responders (specificity 92% and 77% respectively). A decrease in Ve of more than -87% helped to identify complete responders (Sensitivity 89%, Specificity 83%). With theoretical-AIF, changes in kinetic parameters had lower accuracy.ConclusionThere is a good agreement between pathological findings and changes in kinetic parameters obtained with breast-MRI in high spatial and low temporal resolution when measured-AIF is used. Further studies are necessary to confirm whether MRI contrast kinetic parameters can be used earlier as a response predictor to neoadjuvant chemotherapy.

CT-guided biopsies in lung infections in patients with haematological malignancies

CT-guided transparietal lung biopsy in imaging makes it possible to find the pathogenic agent in half of all fungal infections and most bacterial infections (sensitivity=55%, specificity=100%). Performance is decreased in consolidations (50% of infections) compared to masses. Complications, pneumothorax, alveolar bleeding and hemoptysis are generally benign and rarely (<5%) require specific treatment. On the other hand, the diagnostic performance increases significantly with the calibre of 18G co-axial systems compared to 20G. The risk is not related to the number of samples or platelet levels.

Choroid Plexus Neoplasms: Toward a Distinction between Carcinoma and Papilloma Using Arterial Spin-Labeling

SUMMARY: Pediatric choroid plexus papillomas and carcinomas are highly vascularized neoplasms, which are difficult to distinguish with conventional imaging. We aimed to analyze the diagnostic accuracy of PWI, by using both pseudocontinuous arterial spin-labeling and DSC-PWI. We reviewed the PWI of 13 children with choroid plexus neoplasms (7 papillomas and 6 carcinomas). We quantified CBF, relative CBF, and relative CBV in each lesion and compared papillomas and carcinomas. Relative CBF values by using arterial spin-labeling were significantly higher for carcinomas (P = .028). The median value of relative CBF was 1.7 (range, 1.4–1.9) for carcinomas and 0.4 (range, 0.3–0.6) for papillomas. The CBF median value was 115 mL/min/100 g (range, 90–140 mL/min/100 g) for carcinomas and 41 mL/min/100 g (range, 10–73 mL/min/100 g) for papillomas (P = .056). Measures with DSC-PWI were more variable and not significantly different (P = .393). Arterial spin-labeling is a promising technique to differentiate choroid plexus carcinomas and papillomas.

Response Assessment in Pediatric Neuro-Oncology: Implementation and Expansion of the RANO Criteria in a Randomized Phase II Trial of Pediatric Patients with Newly Diagnosed High-Grade Gliomas

SUMMARY: Determination of tumor response to treatment in neuro-oncology is challenging, particularly when antiangiogenic agents are considered. Nontumoral factors (eg, blood-brain barrier disruption, edema, and necrosis) can alter contrast enhancement independent of true tumor response/progression. Furthermore, gliomas are often infiltrative, with nonenhancing components. In adults, the Response Assessment in Neuro-Oncology (RANO) criteria attempted to address these issues. No such guidelines exist yet for children. The ongoing randomized phase II trial, A Study of Avastin (bevacizumab) in Combination With Temolozomide (TMZ) and Radiotherapy in Paediatric and Adolescent Patients With High-Grade Glioma (HERBY), will establish the efficacy and safety of the antiangiogenic agent bevacizumab for the first-line treatment of newly diagnosed high-grade glioma in children (n = 121 patients, enrollment complete). The primary end point is event-free survival (tumor progression/recurrence by central review, second primary malignancy, or death). Determination of progression or response is based on predefined clinical and radiographic criteria, modeled on the RANO criteria and supported by expert pseudoprogression review and the use of standardized imaging protocols. The HERBY trial will also compare conventional MR imaging (T1-weighted and T2/fluid-attenuated inversion recovery sequences) with conventional MR imaging plus diffusion/perfusion imaging for response assessment. It is anticipated that HERBY will provide new insights into antiangiogenic-treated pediatric brain tumors. HERBY will also investigate the practicality of obtaining adequate quality diffusion/perfusion scans in a trial setting, and the feasibility of implementing standard imaging protocols across multiple sites. To date, 61/73 (83.6%) patients with available data have completed diffusion-weighted imaging (uptake of other nonconventional techniques has been limited). Harmonization of imaging protocols and techniques may improve the robustness of pediatric neuro-oncology studies and aid future trial comparability.

Magnetic resonance imaging arterial-spin-labelling perfusion alterations in childhood migraine with atypical aura: a case-control study.

Atypical migraine with aura can be challenging to diagnose. Arterial‐spin‐labelling (ASL) is able to non‐invasively quantify brain perfusion. Our aim was to report cerebral blood flow (CBF) alterations using ASL, at the acute phase of atypical migraine with aura in children.

Moyamoya syndrome in children with neurofibromatosis type 1: Italian-French experience

Moyamoya syndrome (MMS) is the most common cerebral vasculopathy among children with neurofibromatosis type 1 (NF1). In this study, we clinically, radiologically, and genetically examined a cohort that was not previously described, comprising European children with NF1 and MMS. The NF1 genotyping had been registered. This study included 18 children. The mean age was 2.93 ± 3.03 years at the NF1 diagnosis and 7.43 ± 4.27 years at the MMS diagnosis. In seven patients, MMS was diagnosed before or at the same time as NF1. Neuroimaging was performed in 10 patients due to clinical symptoms, including headache (n = 6), cerebral infarction (n = 2), and complex partial seizures (n = 2). The remaining eight children (47%) had MMS diagnosed incidentally. Sixteen children were characterized molecularly. The features of MMS were similar between patients with and without NF1. Additionally, the NF1 phenotype and genotype were similar between children with and without MMS. Interestingly, three children experienced tumors with malignant histology or behavior. The presence of two first cousins in our cohort suggested that there may be potential genetic factors, not linked to NF1, with an additional role respect of NF1 might play a role in MMS pathogenesis. The incidental diagnosis of MMS, and the observation that, among children with NF1, those with MMS were clinically indistinguishable from those without MMS, suggested that it might be worthwhile to add an angiographic sequence to brain MRIs requested for children with NF1. A MMS diagnosis may assist in properly addressing an NF1 diagnosis in very young children who do not fulfill diagnostic criteria.

Tuning Eye-Gaze Perception by Transitory STS Inhibition

Processing eye-gaze information is a key step to human social interaction. Neuroimaging studies have shown that superior temporal sulcus (STS) is highly implicated in eye-gaze perception. In autism, a lack of preference for the eyes, as well as anatomo-functional abnormalities within the STS, has been described. To date, there are no experimental data in humans showing whether it is possible to interfere with eye-gaze processing by modulating STS neural activity. Here, we measured eye-gaze perception before and after inhibitory transcranial magnetic stimulation (TMS) applied over the posterior STS (pSTS) in young healthy volunteers. Eye-gaze processing, namely overt orienting toward the eyes, was measured using eye tracking during passive visualization of social movies. Inhibition of the right pSTS led participants to look less to the eyes of characters during visualization of social movies. Such effect was specific for the eyes and was not observed after inhibition of the left pSTS nor after placebo TMS. These results indicate for the first time that interfering with the right pSTS neural activity transitorily disrupts the behavior of orienting toward the eyes and thus indirectly gaze perception, a fundamental process for human social cognition. These results could open up new perspectives in therapeutic interventions in autism.

Clinical, Radiologic, Pathologic, and Molecular Characteristics of Long-Term Survivors of Diffuse Intrinsic Pontine Glioma (DIPG): A Collaborative Report From the International and European Society for Pediatric Oncology DIPG Registries

Purpose Diffuse intrinsic pontine glioma (DIPG) is a brainstem malignancy with a median survival of < 1 year. The International and European Society for Pediatric Oncology DIPG Registries collaborated to compare clinical, radiologic, and histomolecular characteristics between short-term survivors (STSs) and long-term survivors (LTSs). Materials and Methods Data abstracted from registry databases included patients from North America, Australia, Germany, Austria, Switzerland, the Netherlands, Italy, France, the United Kingdom, and Croatia. Results Among 1,130 pediatric and young adults with radiographically confirmed DIPG, 122 (11%) were excluded. Of the 1,008 remaining patients, 101 (10%) were LTSs (survival ≥ 2 years). Median survival time was 11 months (interquartile range, 7.5 to 16 months), and 1-, 2-, 3-, 4-, and 5-year survival rates were 42.3% (95% CI, 38.1% to 44.1%), 9.6% (95% CI, 7.8% to 11.3%), 4.3% (95% CI, 3.2% to 5.8%), 3.2% (95% CI, 2.4% to 4.6%), and 2.2% (95% CI, 1.4% to 3.4%), respectively. LTSs, compared with STSs, more commonly presented at age < 3 or > 10 years (11% v 3% and 33% v 23%, respectively; P < .001) and with longer symptom duration ( P < .001). STSs, compared with LTSs, more commonly presented with cranial nerve palsy (83% v 73%, respectively; P = .008), ring enhancement (38% v 23%, respectively; P = .007), necrosis (42% v 26%, respectively; P = .009), and extrapontine extension (92% v 86%, respectively; P = .04). LTSs more commonly received systemic therapy at diagnosis (88% v 75% for STSs; P = .005). Biopsies and autopsies were performed in 299 patients (30%) and 77 patients (10%), respectively; 181 tumors (48%) were molecularly characterized. LTSs were more likely to harbor a HIST1H3B mutation (odds ratio, 1.28; 95% CI, 1.1 to 1.5; P = .002). Conclusion We report clinical, radiologic, and molecular factors that correlate with survival in children and young adults with DIPG, which are important for risk stratification in future clinical trials.

Imagerie TDM et IRM de l’angiogenèse tumorale

Angiogenesis is the process of activating dormant endothelial cells to form new vessels, after stimulation and it is essential in tumor growth. In many types of cancer, angiogenesis results from the activation of oncogenes that stimulate the production of Vascular Endothelial Growth Factor (VEGF). However, these newly formed vessels have a great number of abnormalities: increased density of fragile and hyper-permeable microvessels, arterial-venous shunts, caliber abnormalities and flow instabilities susceptible to flow direction inversion according to interstitial pressure. Anti-angiogenic treatments inhibit VEGF activity, perceived as structural and functional normalization of the microvascular pattern, such as reduced density of microvessels and restored morphology of the remaining ones. Conventional imaging techniques are not sensible to these changes, at best they show tumor size stabilization, hence the need of new techniques. Microvascularization imaging can be achieved by detecting functional disturbances to blood flow and not by showing the microvasculature per se. These techniques are based in quantifying the enhancement in tumor due to the passage of contrast agent after injection or protons labeled by a magnetic field. Through these measurements, one can derive interstitial and blood volumes as well as the tissue perfusion and capillary wall permeability. Microvascular imaging has greatly benefited from the improvements seen in CT and MRI equipment allowing large volume coverage with high spatial and temporal resolutions as from the evolutions in the methods to calculate, present and compare maps of the microcirculation and its heterogeneity. However, software to analyze microvascularization are still rare, limiting the techniques application and validation in large scale. Nevertheless, imaging of the microcirculation is useful throughout the care of the oncological patient: it can reinforce the suspicious nature of a lesion, suggest anti-angiogenic treatment efficacy in hypervascular lesions, and show early treatment response before morphological changes as in RECIST criteria.

Child dermoid cyst mimicking a craniopharyngioma: the benefit of MRI T2-weighted diffusion sequence

BackgroundBrain dermoid cysts are very rare lesions. Although benign, these cysts may be associated with devastating complications due to mass effect or meningitis. The discovery of completely asymptomatic dermoid cysts in the pediatric population is exceedingly rare. Despite the advances in imaging modalities, it sometimes remains difficult to exclude the differential diagnosis of craniopharyngioma.Case reportWe describe a 12-year-old boy addressed for suspicion of craniopharyngioma diagnosed by decreased visual acuity, bitemporal hemianopia and a CT scan showing a large hypodense suprasellar lesion with intralesional calcifications. Despite the unusual localization and size of this lesion, the absence of dermal sinus commonly found, and before visualizing a hyperintense mass on MRI-diffusion, the diagnosis of craniopharyngioma was ruled out in favor of a dermoid cyst. Radical excision was performed.ConclusionIn the suprasellar area, craniopharyngioma and dermoid cyst may have very similar radiological aspects: low density masses on CT scan and a hyperintense signal on T1-weighted MRI sequences with a variable signal on T2-weighted sequences. Hitherto, only two cases in literature have described suprasellar dermoid cyst. Their initial diagnosis was facilitated by the presence of a dermal sinus.