An Automated Brain Metastasis Detection and Segmentation System from MRI with a Large Multi-Institutional Dataset

PURPOSE/OBJECTIVE(S)

Developments of automated systems for brain metastasis (BM) detection and segmentation from MRI for assisting early detection and stereotactic radiosurgery (SRS) have been reported but most based upon relatively small datasets from single institutes. This work aims to develop and evaluate a system using a large multi-institutional dataset, and to improve both identification of small/subtle BMs and segmentation accuracy of large BMs.

MATERIALS/METHODS

A 3D U-Net system was trained and evaluated to detect and segment intraparenchymal BMs with a size > 2mm using 1856 MRI volumes from 1791 patients treated with SRS from seven institutions (1539 volumes for training, 183 for validation, and 134 for testing). All patients had 3D post-Gd T1w MRI scans pre-SRS. Gross tumor volumes (GTVs) of BMs for SRS were curated by each institute first. Then, additional efforts were spent to create GTVs for the untreated and/or uncontoured BMs, including central reviews by two radiologists, to improve accuracy of ground truth. The training dataset was augmented with synthetic BMs of 3773 MRIs using a 3D generative pipeline. Our system consists of two U-Nets with one using small 3D patches dedicated for detecting small BMs and another using large 3D patches for segmenting large BMs, and a random-forest based fusion module for combining the two network outputs. The first U-Net was trained with 3D patches containing at least one BM < 0.1 cm3. For detection performance, we measured BM-level sensitivity and case-level false-positive (FP) rate. For segmentation performance, we measured BM-level Dice similarity coefficient (DSC) and 95-percentile Hausdorff distance (HD95). We also stratified performances based upon BM sizes.

RESULTS

For 739 BMs in the 134 testing cases, the overall lesion-level sensitivity was 0.870 with an average case-level FP of 1.34±1.92 (95% CI: 1.02-1.67). The sensitivity was >0.969 for the BMs >0.1 cm3, but dropped to 0.755 for the BMs < 0.1 cm3 (Table 1). The average DSC and HD95 for all detected BMs were 0.786 and 1.35mm. The worse performance for BMs > 20 cm3 was caused by a case with 83 cm3 GTV and artifacts in the MRI volume.

CONCLUSION

We achieved excellent detection sensitivity and segmentation accuracy for BMs > 0.1 cm3, and promising performance for small BMs (<0.1cm3) with a controlled FP rate using a large multi-institutional dataset. Clinical utility for assisting early detection and SRS planning will be investigated. Table 1: Per-lesion detection and segmentation performance stratified by individual BM size. N is the number of BMs in each category.

Telaglenastat plus Everolimus in Advanced Renal Cell Carcinoma: A Randomized, Double-Blinded, Placebo-Controlled, Phase II ENTRATA Trial

PURPOSE

Glutaminase is a key enzyme, which supports elevated dependency of tumors on glutamine-dependent biosynthesis of metabolic intermediates. Dual targeting of glucose and glutamine metabolism by the mTOR inhibitor everolimus plus the oral glutaminase inhibitor telaglenastat showed preclinical synergistic anticancer effects, which translated to encouraging safety and efficacy findings in a phase I trial of 2L+ renal cell carcinoma (RCC). This study evaluated telaglenastat plus everolimus (TelaE) versus placebo plus everolimus (PboE) in patients with advanced/metastatic RCC (mRCC) in the 3L+ setting (NCT03163667).

PATIENTS AND METHODS

Eligible patients with mRCC, previously treated with at least two prior lines of therapy [including ≥1 VEGFR-targeted tyrosine kinase inhibitor (TKI)] were randomized 2:1 to receive E, plus Tela or Pbo, until disease progression or unacceptable toxicity. Primary endpoint was investigator-assessed progression-free survival (PFS; one-sided α <0.2).

RESULTS

Sixty-nine patients were randomized (46 TelaE, 23 PboE). Patients had a median three prior lines of therapy, including TKIs (100%) and checkpoint inhibitors (88%). At median follow-up of 7.5 months, median PFS was 3.8 months for TelaE versus 1.9 months for PboE [HR, 0.64; 95% confidence interval (CI), 0.34-1.20; one-sided P = 0.079]. One TelaE patient had a partial response and 26 had stable disease (SD). Eleven patients on PboE had SD. Treatment-emergent adverse events included fatigue, anemia, cough, dyspnea, elevated serum creatinine, and diarrhea; grade 3 to 4 events occurred in 74% TelaE patients versus 61% PboE.

CONCLUSIONS

TelaE was well tolerated and improved PFS versus PboE in patients with mRCC previously treated with TKIs and checkpoint inhibitors.

Mechanochemical synthesis of high coercivity Nd2(Fe,Co)14B magnetic particles

With increasing demand for magnets in energy conversion systems, the quest for the development and understanding of novel processing routes to produce permanent magnets has become urgent. We report a novel mechanochemical process for the synthesis of Nd₂(Fe,Co)₁₄B magnetic particles with a high coercivity of 12.4 kOe. This process involves the reduction of neodymium oxide, iron oxide, cobalt oxide and boron anhydride in the presence of a calcium reducing agent and a CaO diluent. The formation mechanism of Nd₂(Fe,Co)₁₄B changed with increasing CaO content, and the average crystal size of the Nd₂(Fe,Co)₁₄B particles also increased, resulting in an increase in the coercivity values. The reaction mechanism during milling was revealed through a study of the phase transformations as a function of milling time. It was found that unlike self-propagating reactions, this reduction reaction during milling requires continuous input of mechanical energy to reach a steady state.

Phase I Dose-Escalation Study of Taselisib, an Oral PI3K Inhibitor, in Patients with Advanced Solid Tumors

Taselisib is a potent and selective tumor growth inhibitor through PI3K pathway suppression. Thirty-four patients with locally advanced or metastatic solid tumors were treated (phase I study, modified 3+3 dose escalation; 5 cohorts; 3-16 mg taselisib once-daily capsule). Taselisib pharmacokinetics were dose-proportional; mean half-life was 40 hours. Frequent dose-dependent, treatment-related adverse events included diarrhea, hyperglycemia, decreased appetite, nausea, rash, stomatitis, and vomiting. At 12 and 16 mg dose levels, dose-limiting toxicities (DLT) were observed, with an accumulation of higher-grade adverse events after the cycle 1 DLT assessment window. Pharmacodynamic findings showed pathway inhibition at ≥3 mg in patient tumor samples, consistent with preclinical PIK3CA-mutant tumor xenograft models. Confirmed response rate was 36% for PIK3CA-mutant tumor patients with measurable disease [5/14: 4 breast cancer (3 patients at 12 mg); 1 non-small cell lung cancer], where responses started at 3 mg, and 0% in patients with tumors without known PIK3CA hotspot mutations (0/15).Significance: Preliminary data consistent with preclinical data indicate increased antitumor activity of taselisib in patients with PIK3CA-mutant tumors (in comparison with patients with tumors without known activating PIK3CA hotspot mutations) starting at the lowest dose tested of 3 mg, thereby supporting higher potency for taselisib against PIK3CA-mutant tumors. Cancer Discov; 7(7); 704-15. ©2017 AACR.See related commentary by Rodon and Tabernero, p. 666This article is highlighted in the In This Issue feature, p. 653.

Posterior Fossa Hypervascular Tumour Embolisation

Hemangioblastomas are histologically benign tumours that comprise 7–12% of all posterior fossa lesions. Treatment of these lesions is often complicated by the significant vascularity of the tumour and the difficult surgical resection in the sensitive neural tissue. In such situations, preoperative embolisation facilitates surgery by not only decreasing the intraoperative blood loss, but also by decreasing the total operative time and allowing a near complete resection of the tumour. Though infrequent, fatal complications can occur during preoperative embolisation procedures. We report two such cases in which the tumour bled during the procedure. In both cases, this was effectively managed by arterial pedicle occlusion with NBCA (N-Butyl Cyano acrylate). The early detection, immediate control and the possible causes of this complication is presented.

A multicenter, single-arm, open-label, phase 2 study of apitolisib (GDC-0980) for the treatment of recurrent or persistent endometrial carcinoma (MAGGIE study)

BACKGROUND

The current single-arm, open-label trial was designed to evaluate the activity of apitolisib (GDC-0980), a dual phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor, in patients with advanced endometrial cancer (EC).

METHODS

Patients with recurrent or persistent EC who were treated with 1 to 2 prior lines of chemotherapy but no prior PI3K/mTOR inhibitor received oral apitolisib at a dose of 40 mg daily during 28-day cycles until disease progression or intolerable toxicity occurred. Patients with type I/II diabetes who required insulin were excluded. The primary endpoints were progression-free survival (PFS) at 6 months and objective response rate.

RESULTS

A total of 56 women were enrolled, including 13 (23%) with well-controlled diabetes. Reasons for discontinuation were disease progression (24 patients; 43%), adverse events (13 patients; 23%), and withdrawal by subject (12 patients; 21%). Grade 3/4 apitolisib-related adverse events were hyperglycemia (46%), rash (30%), colitis (5%), and pneumonitis (4%) (toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). The PFS rate at 6 months was 20% (Kaplan-Meier estimate; 95% confidence interval [95% CI], 7%-33%). The objective response rate was 6% (confirmed). The median PFS was 3.5 months (95% CI, 2.7-3.7 months) and the median overall survival was 15.7 months (95% CI, 9.2-17.0 months). Nineteen patients discontinued the study before the first tumor assessment. Dose reductions were required for 4 diabetic (31%) and 18 nondiabetic (42%) patients. Comprehensive molecular profiling of 46 evaluable archival tumor samples demonstrated that 57% of patients had at least 1 alteration in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), phosphatase and tensin homolog (PTEN), or AKT1. All 3 patients with a confirmed response had at least 1 alteration in a PI3K pathway gene.

CONCLUSIONS

The antitumor activity noted with the use of a dose of 40 mg of apitolisib daily was limited by tolerability, especially in diabetic patients. Patients with PI3K pathway mutations may have derived enhanced benefit from apitolisib. Cancer 2016;122:3519-28. © 2016 American Cancer Society.

Abstract 2399: Circulating tumor DNA (ctDNA) analysis of PIK3CA and AKT1 mutations in patients enrolled onto the Phase 1b study of the PI3K inhibitor taselisib (GDC-0032) in solid malignancies

The PI3K signaling pathway is one of the most frequently activated pathways in cancer, and controls critical proliferative and survival processes. Taselisib (GDC-0032) is a novel, oral, selective inhibitor of PI3K, sparing inhibition of PI3Kβ. (Ndubaku CO et al. J Med Chem 2013). Preclinically, taselisib demonstrates enhanced potency in PIK3CA mutant cells, with greater signaling and growth/survival effects in mutant cells vs. wild-type cells. In the phase Ia study with single agent taselisib, partial responses (PRs) were observed in 6/34 enrolled patients. All 6 responses were observed in patients with PIK3CA mutant tumors (Juric D. et al. AACR 2013), indicating the need to determine PIK3CA mutation status from patients treated with taselisib. Circulating tumor DNA (ctDNA) provides an up-to-date liquid biopsy that can be used to detect somatic mutation in oncogenes especially when tumor tissue is not available.

Analysis was undertaken on five cohorts of patients enrolled onto the taselisib Phase 1b study comprised of 106 patients. In total, 87 patients had tumor tissue available for PIK3CA mutation testing. Plasma was collected from 91 patients prior to treatment and 10 patients had matched plasma collected at the study discontinuation visit. Tissue samples were assessed using the Roche cobas PIK3CA mutation test that detects 17 PIK3CA hotspot mutations, of which 47 (54%) tissue samples were positive for PIK3CA mutations. Analysis of PIK3CA and AKT1 mutations from plasma was performed using an Inostics BEAMing digital PCR Oncobeam panel, which detects 8 PIK3CA hotspot mutations and 1 AKT1 mutation. ctDNA was detected in all 91 patients sampled, and ranged from 1.3ng to 1ug per milliliter of plasma. PIK3CA mutations were identified in the plasma of 51 patients (56%), and an AKT1 mutation was identified in one patient. For 80 patients that had both tissue and plasma available for PIK3CA mutation testing, a sensitivity of 81%, a specificity of 74% and an overall accuracy of 78% was observed. Allele frequency ranged from 0.02% to 75.58% with a median of 2.72%. In two cohorts that enrolled hormone receptor positive, HER2 negative breast cancer patients, a sensitivity of 84%, a specificity of 87% and an overall accuracy of 88% was observed between 42 matched tissue and plasma samples. In a patient who experienced a sustained clinical partial response to taselisib in combination with fulvestrant, a decrease in plasma PIK3CA allele frequency was observed from 3.05% in the pretreatment sample to 0.14% in the study discontinuation sample. In summary, analysis of PIK3CA mutations from plasma in patients enrolled onto trials testing the efficacy of taselisib may be a useful surrogate for patients when tissue is unavailable, an observation that is being assessed in ongoing trials.

Citation Format: Timothy R. Wilson, Heidi Savage, Junko Aimi, Jessica Jin, Hema Parmar, Jerry Hsu, Ian Krop, Cristina Saura, Andres Cervantes, Jasgit Sachdev, Manish Patel, Juan Cejalvo, Mafalda Oliveira, Eric Winer, Daniel Von Hoff, Jose Baselga, Dejan Juric. Circulating tumor DNA (ctDNA) analysis of PIK3CA and AKT1 mutations in patients enrolled onto the Phase 1b study of the PI3K inhibitor taselisib (GDC-0032) in solid malignancies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2399. doi:10.1158/1538-7445.AM2015-2399

Abstract A03: Comprehensive predictive biomarker evaluation in two phase II clinical trials of the PI3K/mTOR inhibitor GDC-0980 in metastatic renal cell carcinoma and advanced endometrial cancer

Background: The PI3K/mTOR pathway is frequently activated in cancer by multiple mechanisms. GDC-0980 is a dual pan-PI3K and mTOR (TORC1/2) inhibitor that has been evaluated in two Phase II studies (J Clin Oncol 32:5s, 2014 [suppl; abstr 4525 and 5513]). The randomized ROVER study showed that the PI3K/mTOR inhibitor GDC-0980 did not improve efficacy over the TORC1 inhibitor everolimus in metastatic renal cell carcinoma (mRCC). The single arm MAGGIE study evaluated the activity of GDC-0080 in patients with advanced endometrial cancer (EC). Although some single agent anti-tumor activity was observed, overall evaluation of anti-tumor activity of GDC-0980 was limited by tolerability, especially in diabetic patients. Comprehensive biomarker analysis, including targeted next generation sequencing (NGS) and a panel of biomarkers tailored to each tumor type, was conducted in both Phase II studies to determine the prevalence of PI3K/mTOR pathway alterations, and to assess the association between anti-tumor activity and candidate predictive biomarkers.

Methods: The primary and secondary endpoints included progression-free survival (PFS) and objective response rate (ORR). Archival tissue samples were collected for biomarker analysis, and correlations with efficacy were retrospectively explored. Samples were subjected to targeted NGS (Illumina) covering 88 oncogenes and tumor suppressors, copy number analysis using quantitative-PCR, PTEN immunohistochemistry (IHC), HIF1A IHC (ROVER), and gene expression analysis (NanoString nCounter® System, ROVER).

Results: In ROVER, the median PFS was significantly shorter for GDC-0980 than everolimus. Retrospective biomarker analyses revealed a relationship between VHL mutation status (by NGS) and improved PFS with everolimus but not GDC-0980. High HIF1A protein expression was associated with longer PFS in both arms, whereas low expression of STK11/LKB1 mRNA was associated with benefit with everolimus only. Additional gene expression analysis of PI3K pathway, apoptosis/cell cycle, and tumor immunity related genes will be presented. In MAGGIE, PFS at 6 months was estimated to be 20%, and the ORR was 9% (unconfirmed). Evaluable archival tumor samples were obtained from 88% of the patients and 52% of patients had at least one alteration in PIK3CA, PTEN or AKT1. PTEN loss by IHC was generally well correlated with mutation status determined by NGS. All 5 patients with either a confirmed or investigator assessed partial response had at least one PI3K pathway alteration.

Conclusions: Clinical data to date have suggested that identification of predictive biomarkers for agents targeting PI3K/mTOR signaling is challenging and will require tailoring to specific tumor types. Here we provide comprehensive assessment from two phase II clinical studies of GDC-0980. Our data, although retrospective in nature and requiring confirmation, suggest that pathway activation along the VHL-HIF1A axis may be predictive of anti-tumor activity for mTOR-targeting agents in mRCC. Our results in EC suggest that at least in this study population, frequency of pathway alterations was somewhat lower than observed in prior published data, but the presence of PIK3CA or AKT1 mutations or PTEN loss enriched for anti-tumor activity. Clinical trial information: NCT01442090 (mRCC), NCT01455493 (EC).

Citation Format: Jill M. Spoerke, Vicky Makker, Carol Aghajanian, Powles Thomas, Robert J. Motzer, Jennifer O. Lauchle, Hema Parmar, Houston Gilbert, Wei Lin, Bridget O'Keeffe, Michelle Byrtek, Hartmut Koeppen, Yulei Wang, Shan Lu, Ling-Yuh Huw, Garret M. Hampton, Mark R. Lackner. Comprehensive predictive biomarker evaluation in two phase II clinical trials of the PI3K/mTOR inhibitor GDC-0980 in metastatic renal cell carcinoma and advanced endometrial cancer. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A03.

Abstract OT1-1-01: LORELEI: A Phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/HER2-negative, early stage breast cancer

Background: Taselisib (GDC-0032) is an orally bioavailable, potent, and selective inhibitor of Class I PI3-kinase (PI3K) alpha, gamma, and delta isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that taselisib has enhanced activity against PIK3CA mutant cancer cell lines. Clinical data have also demonstrated confirmed partial responses in patients with PIK3CA mutant breast cancer treated with single-agent taselisib. Preclinical and clinical data also show enhanced antitumor activity when taselisib is combined with either letrozole or fulvestrant.

Study design: LORELEI is a phase II, two-arm, randomized, double-blind, multicenter, neoadjuvant study of letrozole and taselisib versus letrozole and placebo in postmenopausal women with newly diagnosed ER+/HER2-, untreated, stage I-III operable breast cancer. Other relevant eligibility criteria include tumor size ≥ 2 cm, unilateral disease, ECOG PS ≤1, and available and evaluable tumor tissue for central review of PIK3CA mutation analysis. Patients will be randomized (1:1) to receive continuous daily letrozole (2.5 mg) with either placebo or taselisib (4mg on a 5 days on/ 2 days off schedule) for 16 weeks. Study treatment is followed by surgery. Adjuvant treatment will be given as per physician’s discretion. Stratification at randomization is based on tumor size and nodal status.

Endpoints: The co-primary endpoints are overall objective response rate (ORR) by centrally assessed breast magnetic resonance imaging (MRI) via modified RECIST criteria and pathologic complete response (pCR) rate in breast and axilla at time of surgery in all enrolled patients and PIK3CA mutant (MT) patients. Secondary endpoints include ORR by centrally assessed MRI and pCR rate in PIK3CA wild-type (WT) patients. Other secondary endpoints performed in all enrolled patients and separately as per PIK3CA mutation status include: assessment of ORR using breast ultrasound, clinical breast exam (i.e. palpation) and mammography; changes in Ki67 levels from baseline to week 3, baseline to surgery and week 3 to surgery; centrally assessed preoperative endocrine prognostic index (PEPI) score; changes in enhancing tumor volume from baseline to surgery as measured by breast MRI via central assessment. Exploratory analyses include expression of biomarkers predictive of response to letrozole plus taselisib from tumor tissue or blood.

Statistical methods:

The sample size was calculated to detect an absolute percentage increase of 24% in ORR via MRI (40% in the letrozole-placebo arm vs. 64% in the letrozole-taselisib arm in the PIK3CA MT cohort) with 80% power at 16% two-sided significance level. The sample size will also detect an absolute percentage increase of 18% in pCR rate (1% in the letrozole-placebo arm vs 19% in the letrozole-taselisib arm in the PIK3CA MT cohort) with 80% power at 4% two-sided significance level.

Target accrual: Approximately 330 pts at 110 global sites across Europe, North and South America, and Asia-Pacific.

Reference Study ID Numbers: GO28888/BIG-3-13/SOLTI 1205/ABCSG 38.

Citation Format: Cristina Saura, Evandro de Azambuja, Peter Dubsky, Mafalda Oliveira, Kamal S Saini, Christian Fes, Ray S Lin, Timothy R Wilson, Jill Fredickson, Hema Parmar, Jerry Y Hsu, Martine Piccard, Michael Gnant, Jose Baselga. LORELEI: A Phase II randomized, double-blind study of neoadjuvant letrozole plus taselisib (GDC-0032) versus letrozole plus placebo in postmenopausal women with ER-positive/HER2-negative, early stage breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT1-1-01.

Clinical significance of small airway obstruction markers in patients with asthma

BACKGROUND

The role of small airway obstruction in the clinical expression of asthma is incompletely understood.

OBJECTIVE

We tested the hypotheses that markers of small airway obstruction are associated with (i) increased asthma severity, (ii) impaired asthma control and quality of life and (iii) frequent exacerbations.

METHODS

Seventy-four adults with asthma and 18 healthy control subjects underwent impulse oscillometry (IOS), multiple breath inert gas washout (MBW), body plethysmography, single-breath determination of carbon monoxide uptake and spirometry. Patients completed the six-point Asthma Control Questionnaire (ACQ-6) and standardized Asthma Quality of Life Questionnaire [AQLQ(S)]. Asthma severity was classified according to the Global Initiative for Asthma (GINA) treatment steps.

RESULTS

The putative small airway obstruction markers Sacin , resistance at 5 Hz minus resistance at 20 Hz (R5-R20) and reactance area (AX) were not independently associated with asthma severity, control, quality of life or exacerbations. In contrast, markers of total (R5) and mean airway resistance of large and small airways (R20) were significantly higher in the severe asthma group compared with the mild-moderate group (0.47 vs. 0.37, P < 0.05 for R5; 0.39 vs. 0.31, P < 0.01 for R20). The strongest independent contributors to ACQ-6 score were R20 and forced expiratory volume in one second (% pred.), and the strongest independent contributors to AQLQ(S) score were R20 and forced vital capacity (% pred.). A history of one or more exacerbations within the previous year was independently associated with R20.

CONCLUSIONS AND CLINICAL RELEVANCE

Previously reported markers of small airway obstruction do not appear to be independently associated with asthma disease expression. In contrast, the IOS parameter R20, a marker of mean airway resistance of both large and small airways, appears to have independent clinical significance. These observations require confirmation in prospective longitudinal studies.

Abstract 915: Expanded biomarker results from a phase I dose escalation study of GDC-0032, a beta isoform-sparing PI3K inhibitor

The phosphoinositol-3-kinase (PI3K) signaling pathway is one of the most frequently activated pathways in oncogenesis, and controls critical cellular processes such as proliferation, transcription and survival. GDC 0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30 fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. The gene that encodes the p110 alpha isoform of PI3K, PIK3CA, is frequently mutated in breast, colorectal and endometrial cancers. Preclinical data indicate that GDC-0032 has increased activity against PIK3CA mutant cancer cell lines.

As presented by Juric et al., 34 patients were enrolled in this study and dose escalation has been completed (Juric D. et al. AACR 2013, Abstract LB-64). Metabolic partial responses via FDG-PET were observed in 6 out of 13 patients assessed, and clinical partial responses (PRs) were observed in 6 patients, with 5 of these patients having PIK3CA mutant cancers. Tumor tissue was obtained from 30 out of 34 patients enrolled onto the study. The most frequently recruited cancer type was breast cancer (41%) followed by colorectal (15%) and lung cancer (15%). Fourteen patients enrolled onto the study had PIK3CA mutant tumors (41%) as determined using a TaqMan-based PCR assay. Three patients had total loss of PTEN expression, as assessed by immunohistochemical staining, and a further 3 patients had reduced PTEN expression based on a H-score assessment. Out of the 6 patients that had reduced PTEN expression, 2 patients had coexisting mutations with PIK3CA. Where known, 4 out of 5 patients that had a PR showed intact PTEN expression, with the fifth patient having reduced PTEN expression. Samples were further analyzed using an in-house developed PCR-based multiplexed assay that detects activating mutations within an additional ten oncogenes. PIK3CA mutations were largely mutually exclusive with mutations in the Ras pathway, however 3 out of the 14 PIK3CA mutant patients had a coexisting mutation within KRas. A further 2 patients had KRas mutations, 1 patient had a NRas mutation and 2 patients had EGFR mutations. Preliminary analysis suggests lack of benefit in patients with KRas mutations treated with GDC-0032 single agent. Optional on-study biopsies were collected from 2 patients and demonstrated pharmacodynamic inhibition of the PI3K pathway as assessed by reverse phase protein array for approximately 45 endpoints, including 1 patient at the lowest dose. In conclusion, our preliminary data indicates that GDC-0032 demonstrates single agent activity in patients with PIK3CA mutations tumors with unaltered PTEN or MAP-kinase pathways.

Citation Format: Timothy R. Wilson, Heidi Savage, Carol O'Brien, Sandra Sanabria, Ray S. Lin, Marie-Claire Wagle, Yibing Yan, Mark R. Lackner, Hema Parmar, Jerry Y. Hsu, Dejan Juric, Ian E. Krop, Ramesh K. Ramanathan, Daniel D. Von Hoff, Jose Baselga. Expanded biomarker results from a phase I dose escalation study of GDC-0032, a beta isoform-sparing PI3K inhibitor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 915. doi:10.1158/1538-7445.AM2014-915

Raise the bar and lower the dose: current and future strategies for radiation dose reduction in head and neck imaging

SUMMARY

Technologic advances in CT have generated a dramatic increase in the number of CT studies, with a resultant increase in the radiation dose related to CT scanning. Such increase in radiation dose is becoming a concern for the radiology community, especially with increasing public awareness of the dose burden related to examinations. To cope with the increase in CT-related radiation exposure, it is becoming necessary to optimize CT imaging protocols and apply radiation dose reduction techniques to ensure the best imaging with the lowest radiation dose.

Abstract PD1-3: Ph1b study of the PI3K inhibitor GDC-0032 in combination with fulvestrant in patients with hormone receptor-positive advanced breast cancer

Background: GDC-0032 is a next-generation PI3K inhibitor with increased anti-tumor activity against PIK3CA mutant cancers. GDC-0032 is an orally bioavailable, potent, and selective inhibitor of Class I PI3K alpha, delta, and gamma isoforms, with 30-fold less inhibition of the PI3K beta isoform relative to the PI3K alpha isoform. Preclinical data show that GDC-0032 has enhanced activity against PI3K alpha isoform (PIK3CA) mutant breast cancer cell lines. Preclinical data also show enhanced antitumor activity when GDC-0032 is combined with fulvestrant.

Material and Methods: A Phase 1b dose escalation study was conducted with evaluation of GDC-0032 doses ranging from 6-9 mg QD in combination with fulvestrant 500mg q4wk (with loading dose of 500mg at day 1, 14 and 28) in a modified 3+3 design. A dose expansion cohort was conducted at the recommended Phase 2 dose of 6 mg QD. Safety and tolerability of GDC-0032 was assessed, as well as pharmacokinetics (PK), pharmacodynamic (PD) assessment of PI3K pathway inhibition by paired tumor biopsies and by FDG-PET, and anti-tumor activity by RECIST.

Results: As of 1 Mar 2013, 17 patients were enrolled onto this study with the completion of dose escalation. No dose limiting toxicities (DLTs) were observed at either the 6 mg or 9 mg dose levels. Adverse events (AEs) assessed by the investigator as related to GDC-0032 in ≥10% of patients, were diarrhea, hyperglycemia, stomatitis, fatigue, asthenia, decreased appetite, nausea, mucosal inflammation and rash. No observed apparent PK interactions were observed between GDC-0032 and fulvestrant. The median number of prior systemic therapies was 6. Metabolic partial responses via FDG-PET (≥ 20% decrease in mSUVmax) were observed in 8 out of 11 patients assessed (73%). Confirmed partial responses by RECIST have been observed at both the 6mg and 9mg GDC-0032 dose levels. These include patients who have had prior treatment with fulvestrant. As of 29 May 2013, enrollment onto the dose escalation and expansion cohort has been completed (n = 27). Updated data on safety, pharmacodynamics, efficacy, and biomarker correlates will be presented.

Conclusions: The combination of GDC-0032 and fulvestrant is a well-tolerated regimen with promising preliminary efficacy. GDC-0032 is being further investigated in combination with fulvestrant for patients with hormone receptor-positive advanced breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD1-3.

OCEANS: A randomized, double-blinded, placebo-controlled phase III trial of chemotherapy with or without bevacizumab (BEV) in patients with platinum-sensitive recurrent epithelial ovarian (EOC), primary peritoneal (PPC), or fallopian tube cancer (FTC)

LBA5007

Background: BEV, a humanized anti-VEGF monoclonal antibody, has shown a progression-free survival (PFS) benefit in 2 frontline phase III trials in patients with EOC, PPC and FTC. The therapeutic impact of BEV in combination with carboplatin (C) and gemcitabine (G) followed by single agent BEV to disease progression (PD) was evaluated in this phase III trial in the platinum-sensitive recurrent setting. Methods: Patients had recurrent, platinum-sensitive EOC, PPC or FTC, 1 prior regimen, no prior BEV, ECOG performance status 0-1, measurable disease. Subjects were randomized to: Arm A: [IV C (AUC 4, Day (D) 1) + G (1,000 mg/m2 D1 and 8) + placebo (PL) D1] q21D x 6 cycles (c) → PL q21D until PD or unacceptable toxicity (tox) Arm B: [CG + BEV (15 mg/kg) D1] q21D x 6 c → BEV q21D until PD or tox primary endpoint was investigator assessed PFS (RECIST). Secondary endpoints included objective response (OR), overall survival (OS), duration of response and safety. The design provided 80% power to detect a 27% reduction in the hazard of progression or death in Arm B vs A, limiting the overall type I error of 5%. Results: OCEANS enrolled 484 patients (242 per arm) from 4/07 - 1/10, median follow up of 24 months. BEV plus CG followed by single agent BEV to PD significantly increased PFS compared to CG alone (HR=0.484, p<0.0001). OR increased by 21% (p<0.0001). OS data is immature with only 29% of patients having had an event. The safety profile was consistent with other BEV trials. Conclusions: Results show a statistically significant and clinically relevant benefit when bevacizumab is added to chemotherapy in patients with recurrent, platinum sensitive EOC, PPC, and FTC. This is the first phase III trial of an antiangiogenic to demonstrate a clinical benefit to these patients.

[Table: see text]

SABRE-B: an evaluation of paclitaxel and bevacizumab with or without sunitinib as first-line treatment of metastatic breast cancer

BACKGROUND

The vascular endothelial growth factor (VEGF) pathway can be targeted through VEGF neutralization or VEGF receptor (VEGFR) blockade using tyrosine kinase inhibition. Because laboratory models suggest that combining these approaches might be synergistic, we sought to evaluate the feasibility and efficacy of combining sunitinib with paclitaxel + bevacizumab (PB).

METHODS

Patients with human epidermal growth factor receptor 2 (HER2)-negative, metastatic breast cancer receiving first-line chemotherapy were randomized to PB or PB with sunitinib (PBS), with planned escalation of the sunitinib dose.

RESULTS

Forty-six patients were randomized to PB or PBS with sunitinib dosed at 25 mg p.o. daily. Patients receiving PBS encountered substantial toxicity that precluded adequate treatment. The percentage of patients with grade ≥3 adverse events was greater in the PBS arm than the PB arm (83% versus 57%), and sunitinib dosing was modified in 78% of patients, most often due to neutropenia, febrile neutropenia, and fatigue. In addition, 44% of patients had sunitinib dose reduction to 12.5 mg, and 39% required discontinuation. Patients receiving PBS had more bevacizumab treatment interruptions and discontinuations because of toxicity. Median treatment duration was longer in the PB arm compared with the PBS arm (14.1 versus 11.1 weeks), reflecting early treatment discontinuation of PBS. Because of poor tolerability of the addition of sunitinib to PB, the planned sunitinib dose escalation was halted and the study accrual was terminated.

CONCLUSION

Adding sunitinib to standard doses of bevacizumab plus paclitaxel for metastatic breast cancer is not feasible. Different strategies will be required to evaluate whether there is additional clinical benefit to combining VEGF/VEGFR-targeted agents.

Intraosseous haemangioma of the proximal femur: imaging findings

Haemangiomas of bone are uncommon lesions, accounting for approximately 1% of all primary bone tumours. The most frequent sites of involvement are the calvaria and the vertebral column. When haemangiomas involve long tubular bones, they are usually found in the diaphysis or metadiaphysis. Juxta-articular or epiphyseal location for a long bone haemangioma is rare. We present the imaging findings in a case of a histopathologically proven juxta-articular intraosseous haemangioma of the proximal femur. We believe ours is the first report of a haemangioma involving the proximal end of the femur.

Early experiences with diffusion tensor imaging and magnetic resonance tractography in stroke patients

INTRODUCTION

Recent advances in magnetic resonance (MR) diffusion tensor imaging technique enable evaluation of the anisotropy of white matter tracts in-vivo, as well as the integrity of fibre tracts and their orientation. We describe our initial experiences with diffusion tensor imaging and MR tractography techniques to evaluate the structural degeneration of white matter tracts following stroke.

METHODS

Diffusion tensor imaging data were acquired in 11 cases with stroke on a 3T MR imaging scanner, with three-dimensional diffusion tensor imaging-based colour maps and MR tractography performed offline. We evaluated the spatial relationships of the eloquent white matter tracts to the infarcts and areas of haemorrhage, and classified therewith the tracts as either disrupted or displaced. We compared these with the clinical severity of the neurological deficits and prognosis.

RESULTS

A good correlation was found between tractography findings and patient's clinical recovery. All the patients with disruption of white matter tracts had residual deficits on clinical follow-up, whereas the patients with displaced tracts had near complete neurological recovery.

CONCLUSION

Diffusion tensor imaging and MR tractography provide a novel and useful method to directly visualise changes in the white matter tracts in stroke. This can potentially allow clinical-imaging correlation with prognostic potential.

Identification of an epithelial-specific enhancer regulating ESX expression

The Ets transcription factor, ESX, exhibits a unique pattern of epithelial-restricted expression and transactivates genes involved in epithelial differentiation and cancer. The aim of this study was to determine the underlying genetic basis for epithelial-specific expression of ESX. We have identified a 30bp ESX enhancer sequence (EES) approximately 3 kb upstream of the proximal promoter. This region displays enhancer activity in an epithelial-specific manner and deletion of this region abrogates ESX gene transcription. An EES binding protein complex (EBC) was identified through electrophoretic mobility shift assays whose degree of EES binding correlated well with endogenous ESX levels in epithelial cells and was regulated by epithelial differentiation. Understanding the regulation of this element will lend insight into mechanisms of epithelial differentiation and the etiology of breast cancer and may provide novel targets for cancer therapeutic intervention.

Normal variants of the intracranial circulation demonstrated by MR angiography at 3T

Magnetic resonance angiography (MRA) at 3T offers increased signal to noise ratio with better background suppression, leading to exquisite depiction of the intracranial circulation. We present a pictorial review of the normal variations and anomalies of the intracranial circulation detected on MRA performed on a high field 3T clinical scanner using parallel imaging techniques. The salient imaging features of these anomalies and normal variations are discussed with relevance to clinical practice.

Hyperplasia, reduced E-cadherin expression, and developmental arrest in mammary glands oxidatively stressed by loss of mitochondrial superoxide dismutase

To investigate the dysregulating effect of excess oxidative stress on mammary gland development, mammary anlage from newborn female mice with normal (+/+) or absent (null, -/-) manganese superoxide dismutase (SOD2) were excised and implanted under the renal capsule of normal host female nude mice with/without concurrent estrogen supplementation. After 30 days the transplanted glands were excised for wholemount, microscopic and immunohistochemical evaluation. In contrast to the normal growth and maturation of transplanted SOD2+/+ glands, SOD2-/- glands showed arrested development, reduced ductal outgrowth and branching, and absent lumen. These hypomorphic SOD2-/- ducts contained hyperplastic epithelium with increased Ki-67 labelling, loss of E-cadherin expression, and disorganized p63 and cytokeratin (K)-14 expressing basal and myoepithelial components. Estrogen treatment failed to upregulate progesterone receptor or normalize development. These findings suggest that excess oxidative stress from loss of SOD2 function can arrest mammary gland maturation and induce hyperplastic epithelium with early premalignant features.

Epithelial-stromal interactions in the mouse and human mammary gland in vivo

This review deals with the development and hormonal responses of mouse and human mammary glands. A major focus of the review is the role of mesenchymal-epithelial interactions in embryonic mammary development and the role of stromal-epithelial interactions in mammary gland biology. Finally, we present a new model for studying growth, differentiation and hormonal response in human breast epithelium grown in vivo in nude mouse hosts. This new model involves the construction of tissue recombinants composed of human or mouse mammary fibroblasts plus human breast epithelium in polymerized collagen gels. In the model, mouse mammary fibroblasts and human breast fibroblasts appear to support the normal differentiation and growth of human breast epithelium equally. This observation raises the possibility of using mouse mammary fibroblasts from various mutant mice to assess the role of specific paracrine-acting gene products in human mammary gland biology and carcinogenesis.

Estrogen receptor beta inhibits human breast cancer cell proliferation and tumor formation by causing a G2 cell cycle arrest

Studies indicate that estrogen receptor (ER) alpha mediates breast cancer-promoting effects of estrogens. The role of ERbeta in breast cancer is unknown. Elucidating the role of ERbeta in the pathogenesis of breast cancer is important because many human breast tumors express both ERalpha and ERbeta. We show that adenovirus-mediated expression of ERbeta changes the phenotype of ERalpha-positive MCF-7 cells. Estradiol increases cell proliferation and causes tumor formation of MCF-7 cells expressing only ERalpha. In contrast, introducing ERbeta into MCF-7 cells causes an inhibition of proliferation in vitro and prevents tumor formation in a mouse xenograft model in response to estradiol. ERbeta inhibits proliferation by repressing c-myc, cyclin D1, and cyclin A gene transcription, and increasing the expression of p21(Cip1) and p27(Kip1), which leads to a G(2) cell cycle arrest. These results demonstrate that ERalpha and ERbeta produce opposite effects in MCF-7 cells on cell proliferation and tumor formation. Natural or synthetic ERbeta-selective estrogens may lack breast cancer promoting properties exhibited by estrogens in hormone replacement regimens and may be useful for chemoprevention of breast cancer.

Estrogen receptor beta inhibits human breast cancer cell proliferation and tumor formation by causing a G2 cell cycle arrest

Studies indicate that estrogen receptor (ER) alpha mediates breast cancer-promoting effects of estrogens. The role of ERbeta in breast cancer is unknown. Elucidating the role of ERbeta in the pathogenesis of breast cancer is important because many human breast tumors express both ERalpha and ERbeta. We show that adenovirus-mediated expression of ERbeta changes the phenotype of ERalpha-positive MCF-7 cells. Estradiol increases cell proliferation and causes tumor formation of MCF-7 cells expressing only ERalpha. In contrast, introducing ERbeta into MCF-7 cells causes an inhibition of proliferation in vitro and prevents tumor formation in a mouse xenograft model in response to estradiol. ERbeta inhibits proliferation by repressing c-myc, cyclin D1, and cyclin A gene transcription, and increasing the expression of p21(Cip1) and p27(Kip1), which leads to a G(2) cell cycle arrest. These results demonstrate that ERalpha and ERbeta produce opposite effects in MCF-7 cells on cell proliferation and tumor formation. Natural or synthetic ERbeta-selective estrogens may lack breast cancer promoting properties exhibited by estrogens in hormone replacement regimens and may be useful for chemoprevention of breast cancer.

Female genital tuberculosis: hysterosalpingographic appearances

Genital tuberculosis is an important cause of infertility in developing countries and hysterosalpingography (HSG) is the initial procedure performed for the evaluation. Reviewing 37 cases of female genital tuberculosis, we encountered various appearances on HSG. Of 579 HSGs performed over a period of 4 years, 492 (85%) were performed as part of infertility work up. Genital tuberculosis was found in 6.3% of all the patients who underwent HSGs and 7.5% of all patients investigated for infertility. The various features of proven tuberculosis cases are illustrated in this pictorial review. We briefly discuss the pathology and these appearances along with radiopathological correlation.

A novel method for growing human breast epithelium in vivo using mouse and human mammary fibroblasts

A novel system is described for studying the growth of normal human mammary epithelium in vivo as grafts in athymic nude mice. The key feature of this model is reconstitution of the epithelial-stromal interactions required for normal growth and differentiation of the human mammary epithelium, which produces ducts that are comparable to those in the normal human mammary gland. Human breast epithelial organoids were combined with mammary fibroblasts from mouse or human origin in collagen gels, which were subsequently transplanted under the renal capsule of female nude mice hosts. The resulting grafts showed an increase in the ductal density compared with that observed previously. These ducts expressed appropriate markers for luminal and myoepithelial cells and steroid receptors. Treatment of the host with diethylstilbestrol or estradiol and progesterone significantly increased the number of ducts observed and increased cell proliferation. The grafts also displayed production of beta-casein and milk fat globule membrane protein when the hosts were allowed to become pregnant. This model allows for a variety of epithelial and stromal cells to be used in combination, which would aid in understanding key factors that regulate normal human mammary gland development.

Magnetic resonance arthrography in recurrent anterior shoulder instability as compared to arthroscopy: a prospective comparative study

AIM

To evaluate the accuracy of magnetic resonance (MR) arthrographic imaging in the diagnosis of glenoid labral and ligament tears in recurrent shoulder instability.

SETTINGS AND DESIGN

Prospective, comparative study at a tertiary care centre.

MATERIAL AND METHODS

Patients with three or more episodes of anterior shoulder dislocation were enrolled in the study. They were subjected to magnetic resonance arthrography (MRA) for delineation of abnormalities. The findings obtained at MRA were compared with those found at arthroscopy and surgical exploration.

RESULTS

MRA detected glenoid tears in all 22 patients with 20 (90%) patients having antero-inferior tears, 3 (14%) patients had superior labral involvement and 2 (10%) patients had posterior labral abnormality. On arthroscopy, antero-inferior, superior and posterior labral tear were found in 21 (95%), 5 (22%) and 7 (32%) patients respectively. MRA showed a sensitivity of 95%, and a specificity of 100% for the detection of the antero-inferior labral tears. The sensitivity of MRA for the detection of superior, middle and inferior glenohumeral ligament tear was 83%, 80% and 86% with a specificity of 100%, 71% and 93% respectively. MRA was 100% sensitive for the detection of rotator cuff injuries and detection of bony lesions like Hill-Sach's and bony Bankart's lesion.

CONCLUSIONS

MRA is a sensitive and specific modality for evaluation of anterior shoulder instability.

Subcutaneous rupture of hepatic hydatid cyst

Hepatic hydatid cysts are common entities. We present an unusual case of a hepatic hydatid cyst which had ruptured into the subcutaneous tissues of the anterior abdominal wall. The possible causes, imaging features and recent literature are reviewed.

MR imaging in intramedullary cysticercosis

Although intramedullary spinal cord cysticercosis (IMC) is uncommon, its presence is being increasingly recognised by magnetic resonance imaging. We studied six patients from an endemic region and present the MRI features and clinical correlation of IMC. Six patients who presented with para- or quadriplegia were studied by contrast enhanced spinal MRI. Prompted by the spinal lesions, all patients underwent brain MRI. Clinical data and laboratory studies were reviewed in all patients. Definite diagnosis was established in the form of response to drug therapy (n = 4) and histopathology (n = 2). Follow-up MRI studies of spine and brain were obtained in four patients 2 months after they started medical treatment, regardless of surgery. Five patients showed fusiform and focal enlargement of the spinal cord (cervical 2, thoracic 3). Well-defined cysts with a slightly hyperintense mural nodule were identified in five patients in Ti-weighted images (T1WI). All cysts were hyperintense on T2WI and merged with the surrounding oedema. Oedema extended one to three vertebral levels above or below the cyst. Post-contrast T1WI showed well-defined, ring enhancing lesions with smooth walls in all patients. Symptoms in all patients correlated with the level of the lesions. Brain studies demonstrated lesions in just two patients. Histopathological confirmation was obtained in two patients. Follow-up spinal MRI was normal in two patients, following 2 months of treatment while residual and smaller lesions were seen in two patients. Two patients were asymptomatic and denied follow-up MRI. MRI of spinal cysticercosis were typical of and similar to those seen in cerebral lesions in our patients and corresponded to the level of symptoms. All cysts were surrounded by oedema. Two of four patients showed residual lesions after 2 months of therapy and 33 % of patients showed concomitant intracranial lesions.

An enhancer sequence directs LacZ expression to developing pharyngeal endoderm in transgenic mice

The murine Hoxc-6 homeobox gene comprises three exons with two distinct promoters (PRI and PRII) located 9 kb apart. To characterise the PRII promoter, a region 3 kb upstream of the transcription start site was sequenced, and an Antananapedia-like consensus binding sequence was found (Coletta et al., 1991). A LacZ reporter gene construct, containing three copies of this sequence, directs highly specific expression in cells forming pharyngeal endoderm in transgenic mice. Expression was first detected in a few individual anterior endoderm cells at E7.5, which increase in number up to E9.5, where expression was clearly visible in the pharyngeal endoderm. Expression of the endodermal genes HNF3beta, Pax-9, Shh, and Nkx2.5 showed colocalization with the LacZ-positive cells in the foregut and pharyngeal endoderm. This novel enhancer provides a means of tracking the morphogenetic movement of endodermal cells fated to form the foregut.

Isolated symmetrical mediastinal lipomatosis

Symmetrical mediatinal lipomatosis is a rare benign condition characterized by deposition of a large amount of mature adipose tissue within the mediastinum. Usually secondary to exogenous obesity, administration of steroids and Cushing's disease, it is more common in middle-aged males and is associated with alcohol abuse. Various other associations have been reported. CT and MRI can decisively diagnose this benign condition, which also helps in deciding treatment options. We present a case of a young female with a bizarre appearance on chest radiographs. Isolated, bilaterally symmetrical mediastinal lipomatosis was diagnosed on CT and MRI. The patient was thin and did not consume alcohol or steroids. Cushing's disease and other known associations were excluded.

Intrasacral meningocele with tethered cord syndrome

We present a 65 year old, relatively asymptomatic man, who was found to have an intrasacral meningocele with tethered cord syndrome on Magnetic Resonance Imaging (MRI). Incidental detection of this entity at such an old age is very unusual.

Cytoskeletal microdifferentiation: a mechanism for organizing morphological plasticity in dendrites

Experimental evidence suggests that microfilaments and microtubules play contrasting roles in regulating the balance between motility and stability in neuronal structures. Actin-containing microfilaments are associated with structural plasticity, both during development when their dynamic activity drives the exploratory activity of growth cones and after circuit formation when the actin-rich dendritic spines of excitatory synapses retain a capacity for rapid changes in morphology. By contrast, microtubules predominate in axonal and dendritic processes, which appear to be morphologically relatively more stable. To compare the cytoplasmic distributions and dynamics of microfilaments and microtubules we made time-lapse recordings of actin or the microtubule-associated protein 2 tagged with green fluorescent protein in neurons growing in dispersed culture or in tissue slices from transgenic mice. The results complement existing evidence indicating that the high concentrations of actin present in dendritic spines is a specialization for morphological plasticity. By contrast, microtubule-associated protein 2 is limited to the shafts of dendrites where time-lapse recordings show little evidence for dynamic activity. A parallel exists between the partitioning of microfilaments and microtubules in motile and stable domains of growing processes during development and between dendrite shafts and spines at excitatory synapses in established neuronal circuits. These data thus suggest a mechanism, conserved through development and adulthood, in which the differential dynamics of actin and microtubules determine the plasticity of neuronal structures.

Arachnoiditis associated with arachnoid cyst formation and cord tethering following myelography: magnetic resonance features

The reported incidence of clinically significant arachnoiditis following oil-based contrast media myelography is approximately 1%. The incidence of arachnoiditis in the dorsal spine is even more rare. Acquired arachnoid cyst formation can occur with arachnoiditis of various aetiologies. A case is presented of a patient with chronic backache, radiculopathy, weakness and muscle wasting, who had undergone myelography with oil-based contrast media about 28 years ago. There was no history of spinal surgery, spinal canal stenosis, disc disease or trauma, all of which are known to increase the risk of arachnoiditis. Magnetic resonance imaging features are presented in this case of arachnoiditis with arachnoid cyst formation, and cord tethering.

Cystic lumbar nerve sheath tumours: MRI features in five patients

Intraspinal cystic lumbar nerve sheath tumours constitute an uncommon subset of tumours with distinct clinico-biological behaviour. The MRI findings in five such cases are presented. Four of these were cystic schwannomas and one was a cystic neurofibroma. The pathology, MRI findings and the differential diagnosis of these rare tumours are analysed.

Imaging findings in rabies encephalitis

SUMMARY

Rabies encephalitis is perhaps one of the few infectious diseases that command attention and fear not only from the layman but also from physicians. The unique mode of transmission, the virtually exclusive neurotransmission shown by the agent, and the complete hopelessness of the established disease sets rabies apart from other zoonoses transmitted to man. Rabies encephalitis is a fatal disease and its diagnosis is usually based on the clinical presentations and findings. Hence, imaging in rabies is seldom done, and imaging findings in rabies encephalitis have rarely been described. We present the imaging findings in two confirmed cases of rabies encephalitis in which antemortem diagnosis was obtained by corneal impression smears showing the presence of viral antigens. The differential diagnosis of the imaging findings as well as the role and the relevance of imaging in the diagnosis of this disease are discussed. The current literature on the subject is also reviewed.

A longitudinal analysis of cytotoxic T lymphocyte precursor frequencies to the hepatitis B virus in chronically infected patients

Individuals with acute hepatitis B virus (HBV) infection characteristically mount a strong, multispecific cytotoxic T lymphocyte (CTL) response that is effective in eradicating virus. In contrast, this response in chronic carriers is usually weak or undetectable. Since it is generally acknowledged that HBV pathogenesis is immune-mediated, the occurrence of episodes of active liver disease in many carriers suggests that these individuals can mount active CTL responses to HBV. To see whether the detection of circulating CTLs is related to these flare episodes, we have determined the CTL precursor (CTLp) frequencies to HLA-A2-restricted viral peptides in seven patients over a 12-24-month period of their disease. Limiting dilution analyses (LDA) were performed longitudinally to five epitopes comprising the viral capsid (HBc), envelope (HBs) and polymerase (pol) proteins. Assays were performed against a mixture of peptides, or against each individual peptide, to measure overall CTL activity and the multispecificity of the responses, respectively. Since two of the patients were treated with recombinant human interleukin-12 (rHuIL-12) at the time, with one individual achieving complete disease remission a year later after being treated with interferon-alpha, we were also able to examine the effects of these cytokines on HBV cytotoxicity. Our results indicate that weak but detectable CTL responses do occur in chronic carriers which are generally associated with disease flares, although CTLps were also seen occasionally during minimal disease activity. The range of specificities varied between individuals and within each individual during the course of the disease. Finally, we also provide evidence that CTL reactivity is stimulated following treatment with certain cytokines, but is dependent on the time of administration.

Intramedullary tuberculomas. MR findings in seven patients

PURPOSE

To describe the MR findings in intramedullary tuberculomas and to discuss the usefulness of MR in the management of this pathology.

MATERIAL AND METHODS

A retrospective study of 7 patients from 21 to 60 years of age with clinical and radiological evidence of intramedullary tuberculomas was undertaken. Both T1- and T2-weighted images (WI) were obtained along with postcontrast T1WI. Signal intensities (SIs) of the granulomas were compared with SIs of the normal spinal cord.

RESULTS

Six patients showed focus of tuberculosis elsewhere in the body. Six out of 7 showed fusiform swelling of the cord. Ill-defined iso-intensity (in 4 patients) to hyperintensity (in 3 patients) was seen at the site of granuloma on T1WI. On T2WI, 2 patients revealed a hypointense area (with disc enhancement). An iso-hypointense rim was seen surrounding a hyperintense centre in 5 patients (with rim enhancement). Adjacent oedema was seen in all patients. In 2 patients meningeal enhancement was also seen. In 2 patients the histopathology following surgical biopsy confirmed the diagnosis. In the remaining 5 patients, another known focus of tuberculosis elsewhere in the body and a marked response to antitubercular treatment was considered confirmatory for tuberculomas.

CONCLUSION

Hypo- or iso-intensity on T2WI within the spinal cord with surrounding hyperintense oedema is suggestive of intramedullary tuberculomas. Central hyperintensities are also detected at times due to a variable amount of caseous necrosis with liquefaction. On T1WI, fusiform swelling of the cord is seen along with iso- to hyperintense foci, surrounded by hypointense oedema of the cord. Such findings should prompt a contrast-enhanced study, which may show single or conglomerate disc- or ring-enhancing lesions. MR thus plays an important role not only in detection and diagnosis, but also in deciding the treatment options and in the follow-up of those patients.

Tuberculosis of the sternum and clavicle: imaging findings in 15 patients

OBJECTIVE

To describe the imaging findings in sterno-clavicular tubercular involvement.

DESIGN AND PATIENTS

Fifteen patients with pathologically proven tuberculosis of the sternum and clavicle were retrospectively evaluated. Routine radiography, computed tomography (CT) and magnetic resonance imaging (MRI) were used in some or all of the patients. Clinical information and imaging features were evaluated in each case.

RESULTS

Eight patients had sternoclavicular joint (SCJ) involvement, five had isolated sternal involvement and two had isolated clavicular involvement. Seven patients were evaluated with only CT, six with only MRI and two with both. There were eight male and seven female patients, varying in age between 16 and 78 years. Fever, swelling and pain were common presenting symptoms. Two patients were HIV positive. Radiographs were positive in only eight patients. Destruction and signal intensity (SI) changes of the sternum and clavicle, destruction of the cartilage, soft tissue changes representing granulation tissue/abscess, displacement of the adjacent structures (vessels, trachea, etc.) and inflammatory changes in the adjacent structures in the form of cellulitis and myositis were common imaging features.

CONCLUSIONS

All imaging methods can provide complementary information regarding sterno-clavicular tubercular involvement that is helpful for determination of the therapy. MRI is useful in determining the extent of the lesion, particularly marrow involvement and soft tissue extent.

Imaging findings in a giant hepatic artery aneurysm

A rare case of relatively asymptomatic giant hepatic artery aneurysm of atherosclerotic aetiology is presented. The importance of imaging findings in the diagnosis of this condition and the differential diagnosis including the pertinent literature on the topic is discussed.

Activity-regulated, cytoskeleton-associated protein (Arc) is essential for visceral endoderm organization during early embryogenesis

Activity-regulated, cytoskeleton-associated protein (Arc) was first identified as an immediate-early gene regulated by synaptic activity. We have studied its functional role in vivo using a gene-targeting approach. We found that Arc is encoded by a single exon, and Arc mRNA is ubiquitously expressed in early mouse embryos. Homozygous Arc mutants are severely growth-retarded, fail to gastrulate and subsequently die before day 8.5 of embryogenesis. Further analysis revealed severe disorganization of visceral endoderm formation, and total separation and ectopic location of embryonic and extraembryonic structure. These findings demonstrate that Arc function is essential for early embryo development and patterning in mice, and support the hypothesis that signaling from visceral endoderm is essential for normal patterning of the extraembryonic and embryonic structure.