Deep learning based correction of RF field induced inhomogeneities for T2w prostate imaging at 7 T.

At ultrahigh field strengths images of the body are hampered by B1 -field inhomogeneities. These present themselves as inhomogeneous signal intensity and contrast, which is regarded as a "bias field" to the ideal image. Current bias field correction methods, such as the N4 algorithm, assume a low frequency bias field, which is not sufficiently valid for T2w images at 7 T. In this work we propose a deep learning based bias field correction method to address this issue for T2w prostate images at 7 T. By combining simulated B1 -field distributions of a multi-transmit setup at 7 T with T2w prostate images at 1.5 T, we generated artificial 7 T images for which the homogeneous counterpart was available. Using these paired data, we trained a neural network to correct the bias field. We predicted either a homogeneous image (t-Image neural network) or the bias field (t-Biasf neural network). In addition, we experimented with the single-channel images of the receive array and the corresponding sum of magnitudes of this array as the input image. Testing was carried out on four datasets: the test split of the synthetic training dataset, volunteer and patient images at 7 T, and patient images at 3 T. For the test split, the performance was evaluated using the structural similarity index measure, Wasserstein distance, and root mean squared error. For all other test data, the features Homogeneity and Energy derived from the gray level co-occurrence matrix (GLCM) were used to quantify the improvement. For each test dataset, the proposed method was compared with the current gold standard: the N4 algorithm. Additionally, a questionnaire was filled out by two clinical experts to assess the homogeneity and contrast preservation of the 7 T datasets. All four proposed neural networks were able to substantially reduce the B1 -field induced inhomogeneities in T2w 7 T prostate images. By visual inspection, the images clearly look more homogeneous, which is confirmed by the increase in Homogeneity and Energy in the GLCM, and the questionnaire scores from two clinical experts. Occasionally, changes in contrast within the prostate were observed, although much less for the t-Biasf network than for the t-Image network. Further, results on the 3 T dataset demonstrate that the proposed learning based approach is on par with the N4 algorithm. The results demonstrate that the trained networks were capable of reducing the B1 -field induced inhomogeneities for prostate imaging at 7 T. The quantitative evaluation showed that all proposed learning based correction techniques outperformed the N4 algorithm. Of the investigated methods, the single-channel t-Biasf neural network proves most reliable for bias field correction.

SAR and temperature distributions in a database of realistic human models for 7 T cardiac imaging.

PURPOSE: To investigate inter-subject variability of B1+ , SAR and temperature rise in a database of human models using a local transmit array for 7 T cardiac imaging. METHODS: Dixon images were acquired of 14 subjects and segmented in dielectric models with an eight-channel local transmit array positioned around the torso for cardiac imaging. EM simulations were done to calculate SAR distributions. Based on the SAR distributions, temperature simulations were performed for exposure times of 6 min and 30 min. Peak local SAR and temperature rise levels were calculated for different RF shim settings. A statistical analysis of the resulting peak local SAR and temperature rise levels was performed to arrive at safe power limits. RESULTS: For RF shim vectors with random phase and uniformly distributed power, a safe average power limit of 35.7 W was determined (first level controlled mode). When RF amplitude and phase shimming was performed on the heart, a safe average power limit of 35.0 W was found. According to Pennes' model, our numerical study suggests a very low probability of exceeding the absolute local temperature limit of 40 °C for a total exposure time of 6 min and a peak local SAR of 20 W/kg. For a 30 min exposure time at 20 W/kg, it was shown that the absolute temperature limit can be exceeded in the case where perfusion does not change with temperature. CONCLUSION: Safe power constraints were found for 7 T cardiac imaging with an eight-channel local transmit array, while considering the inter-subject variability of B1+ , SAR and temperature rise.

A local multi-transmit coil combined with a high-density receive array for cerebellar fMRI at 7 T.

The human cerebellum is involved in a wide array of functions, ranging from motor control to cognitive control, and as such is of great neuroscientific interest. However, its function is underexplored in vivo, due to its small size, its dense structure and its placement at the bottom of the brain, where transmit and receive fields are suboptimal. In this study, we combined two dense coil arrays of 16 small surface receive elements each with a transmit array of three antenna elements to improve BOLD sensitivity in the human cerebellum at 7 T. Our results showed improved B1+ and SNR close to the surface as well as g-factor gains compared with a commercial coil designed for whole-head imaging. This resulted in improved signal stability and large gains in the spatial extent of the activation close to the surface (<3.5 cm), while good performance was retained deeper in the cerebellum. Modulating the phase of the transmit elements of the head coil to constructively interfere in the cerebellum improved the B1+ , resulting in a temporal SNR gain. Overall, our results show that a dedicated transmit array along with the SNR gains of surface coil arrays can improve cerebellar imaging, at the cost of a decreased field of view and increased signal inhomogeneity.

Intersubject specific absorption rate variability analysis through construction of 23 realistic body models for prostate imaging at 7T.

PURPOSE: For ultrahigh field (UHF) MRI, the expected local specific absorption rate (SAR) distribution is usually calculated by numerical simulations using a limited number of generic body models and adding a safety margin to take into account intersubject variability. Assessment of this variability with a large model database would be desirable. In this study, a procedure to create such a database with accurate subject-specific models is presented. Using 23 models, intersubject variability is investigated for prostate imaging at 7T with an 8-channel fractionated dipole antenna array with 16 receive loops. METHOD: From Dixon images of a volunteer acquired at 1.5T with a mockup array in place, an accurate dielectric model is built. Following this procedure, 23 subject-specific models for local SAR assessment at 7T were created enabling an extensive analysis of the intersubject B1+ and peak local SAR variability. RESULTS: For the investigated setup, the maximum possible peak local SAR ranges from 2.6 to 4.6 W/kg for 8 × 1 W input power. The expected peak local SAR values represent a Gaussian distribution (µ/σ=2.29/0.29 W/kg) with realistic prostate-shimmed phase settings and a gamma distribution Γ(24,0.09) with multidimensional radiofrequency pulses. Prostate-shimmed phase settings are similar for all models. Using 1 generic phase setting, average B1+ reduction is 7%. Using only 1 model, the required safety margin for intersubject variability is 1.6 to 1.8. CONCLUSION: The presented procedure allows for the creation of a customized model database. The results provide valuable insights into B1+ and local SAR variability. Recommended power thresholds per channel are 3.1 W with phase shimming on prostate or 2.6 W for multidimensional pulses.

Expression of the hypoxia-inducible monocarboxylate transporter MCT4 is increased in triple negative breast cancer and correlates independently with clinical outcome.

BACKGROUND: (18)Fluor-deoxy-glucose PET-scanning of glycolytic metabolism is being used for staging in many tumors however its impact on prognosis has never been studied in breast cancer. METHODS: Glycolytic and hypoxic markers: glucose transporter (GLUT1), carbonic anhydrase IX (CAIX), monocarboxylate transporter 1 and 4 (MCT1, 4), MCT accessory protein basigin and lactate-dehydrogenase A (LDH-A) were assessed by immunohistochemistry in two cohorts of breast cancer comprising 643 node-negative and 127 triple negative breast cancers (TNBC) respectively. RESULTS: In the 643 node-negative breast tumor cohort with a median follow-up of 124 months, TNBC were the most glycolytic (≈70%), followed by Her-2 (≈50%) and RH-positive cancers (≈30%). Tumoral MCT4 staining (without stromal staining) was a strong independent prognostic factor for metastasis-free survival (HR=0.47, P=0.02) and overall-survival (HR=0.38, P=0.002). These results were confirmed in the independent cohort of 127 cancer patients. CONCLUSION: Glycolytic markers are expressed in all breast tumors with highest expression occurring in TNBC. MCT4, the hypoxia-inducible lactate/H(+) symporter demonstrated the strongest deleterious impact on survival. We propose that MCT4 serves as a new prognostic factor in node-negative breast cancer and can perhaps act soon as a theranostic factor considering the current pharmacological development of MCT4 inhibitors.

Unrolled Optimization via Physics-Assisted Convolutional Neural Network for MR-Based Electrical Properties Tomography: A Numerical Investigation.

Magnetic Resonance imaging based Electrical Properties Tomography (MR-EPT) is a non-invasive technique that measures the electrical properties (EPs) of biological tissues. In this work, we present and numerically investigate the performance of an unrolled, physics-assisted method for 2D MR-EPT reconstructions, where a cascade of Convolutional Neural Networks is used to compute the contrast update. Each network takes in input the EPs and the gradient descent direction (encoding the physics underlying the adopted scattering model) and returns as output the updated contrast function. The network is trained and tested in silico using 2D slices of realistic brain models at 128 MHz. Results show the capability of the proposed procedure to reconstruct EPs maps with quality comparable to that of the popular Contrast Source Inversion-EPT, while significantly reducing the computational time.

Uncertainty Assessment for Deep Learning Radiotherapy Applications.

In the last 5 years, deep learning applications for radiotherapy have undergone great development. An advantage of radiotherapy over radiological applications is that data in radiotherapy are well structured, standardized, and annotated. Furthermore, there is much to be gained in automating the current laborious workflows in radiotherapy. After the initial peak in the belief in deep learning, researchers have also identified fundamental weaknesses of deep learning. The basic assumption in deep learning is that the training and test data originate from the same data generating process. This is not always clear-cut in clinical practice, eg, data acquired with 2 different scanners of different vendors might not originate from the same data generating process. Furthermore, it is important to realize residual uncertainties remain even if test data arise from the same data generating process as the training data. As deep learning applications are being introduced in clinical radiotherapy workflows, a deep learning model must express to a user when a prediction exceeds a certain uncertainty threshold. The literature on uncertainty assessment for deep learning applications in radiotherapy is still in its infancy; however, quite a body of literature exists on the validity and uncertainty of deep learning models for computer vision applications. This paper tries to explain these general concepts to the radiotherapy community. Concepts of epistemic and aleatoric uncertainties and techniques to model them in deep learning are described in detail. It is discussed how they can be applied to maximize confidence in automated deep learning-driven workflows. Their usage is demonstrated in 3 examples from radiotherapy literature on deep learning applications, ie, dose prediction, synthetic CT generation, and contouring. In the final part, some of the key elements to ensure confidence and automatic alerting that are still missing are discussed. State-of-the-art automatic solutions for checking within-distribution vs out-of-distribution test samples are discussed. However, these methodologies are still immature, and strict QA protocols and close human supervision will still be needed. Nevertheless, deep learning models offer already much value for radiotherapy.

Pathological complete response and survival according to the level of HER-2 amplification after trastuzumab-based neoadjuvant therapy for breast cancer.

BACKGROUND: We analysed whether the level of human epidermal growth factor receptor-2 (HER-2) amplification significantly influenced either pathological complete response (pCR) or recurrence-free survival (RFS) and overall survival (OS) after trastuzumab-based neoadjuvant therapy. METHODS: In all, 99 patients with an HER-2-amplified breast tumour treated with trastuzumab-based neoadjuvant therapy were included. Tumours were classified as low amplified (LA; 6-10 signals per nuclei) or highly amplified (HA; >10 signals). Pathological response was assessed according to Chevallier's classification (pCR was defined as grade 1 or 2). Median follow-up lasted 46 months (6-83). Cox uni- and multivariate analyses were performed. RESULTS: In all, 33 tumour samples were LA and 66 were HA. The pCR in HA tumours was significantly higher than in LA tumours (55% vs 24%, P=0.005), whereas no association was found between the pCR rate and tumour stage, grade or hormone receptor status. In multivariate analysis, the pathological nodal status (P=0.005) and adjuvant trastuzumab (P=0.037) were independently associated with RFS, whereas the level of HER-2 amplification nearly reached statistical significance (P=0.057). There was no significant difference between LA and HA tumours for OS (P=0.22, log-rank). CONCLUSION: The level of HER-2 gene amplification significantly influenced pCR but not RFS or OS in non-metastatic breast cancer treated with trastuzumab-based neoadjuvant therapy. However, RFS in patients with HA tumours tended to be shorter.

[Papillary thyroid microcarcinomas: review of 230 cases]. / Les microcarcinomes papillaires de la glande tyroïde: à propos de 230 cas.

OBJECTIVES: Papillary microcarcinoma (PMC) is one of the most frequent pathological forms of thyroid cancer Here, we describe the circumstances of diagnosis and the clinical and pathological characteristics of this tumour We also analyze the therapeutic management and compare it with the recent published guidelines. METHODS: Between 2000 and 2006, a total of 230 patients with a PMC of the thyroid gland were included in this retrospective study. We have investigated the correlations between some pathological parameters (plurifocality, lymph node invasion...) and several factors (age, gender, tumour size...). RESULTS: The diagnosis of PMC was suspected in the preoperative period in 15% of the patients, and was confirmed intraoperatively by the pathologist in 42% of the cases. Plurifocal or bilateral PMC were discovered in respectively 30 and 17% of the patients. The rate of lymph node invasion in the central neck (level VI) was 26%. An elevated tumor size was correlated with a higher rate of plurifocal or bilateral PMC and of lymph node metastasis (p < 0.05). The indications for postoperative radioiodine therapy were reduced by approxiately 50% in the second part of our study. There were no case of thyroid PMC-related death. CONCLUSIONS: Even for these small tumours, tumour size remains correlated with the tumour aggressiveness. The place of radioiodine therapy in the management of thyroid PMC was progressively reduced because of the good prognosis of this tumour.

Opening a new window on MR-based Electrical Properties Tomography with deep learning.

In the radiofrequency (RF) range, the electrical properties of tissues (EPs: conductivity and permittivity) are modulated by the ionic and water content, which change for pathological conditions. Information on tissues EPs can be used e.g. in oncology as a biomarker. The inability of MR-Electrical Properties Tomography techniques (MR-EPT) to accurately reconstruct tissue EPs by relating MR measurements of the transmit RF field to the EPs limits their clinical applicability. Instead of employing electromagnetic models posing strict requirements on the measured MRI quantities, we propose a data driven approach where the electrical properties reconstruction problem can be casted as a supervised deep learning task (DL-EPT). DL-EPT reconstructions for simulations and MR measurements at 3 Tesla on phantoms and human brains using a conditional generative adversarial network demonstrate high quality EPs reconstructions and greatly improved precision compared to conventional MR-EPT. The supervised learning approach leverages the strength of electromagnetic simulations, allowing circumvention of inaccessible MR electromagnetic quantities. Since DL-EPT is more noise-robust than MR-EPT, the requirements for MR acquisitions can be relaxed. This could be a major step forward to turn electrical properties tomography into a reliable biomarker where pathological conditions can be revealed and characterized by abnormalities in tissue electrical properties.

Prognostic factors in 1,038 women with metastatic breast cancer.

BACKGROUND: Treatment of metastatic breast cancer (MBC) remains palliative. Patients with MBC represent a heterogeneous group whose prognosis and outcome may be dependent on host factors. The purpose of the present study was dual: first, to draw up a list of factors easily available in everyday clinical practice requiring no sophisticated or costly methods and second, to provide results from a large cohort of women who underwent diagnostic and treatment at a single institution. PATIENTS AND METHODS: From 1975 to 2005, a total of 1,038 women with MBC during their follow-up were included in this retrospective analysis. Patients were subsequently assigned to five groups according to the period of metastatic diagnosis. RESULTS: It is shown that age at initial diagnosis, hormonal receptor status and site of metastasis are the most relevant prognostic factors for predicting survival from the time of metastastic occurrence. It is also shown that a metastasis-free interval is an easily and immediately available multifactorial prognostic index reflecting the multiparametric variability of the disease. CONCLUSION: These fundamental observations may assist physicians in evaluating the survival potential of patients and in directing them toward the appropriate therapeutic decision.

The sentinel lymph node procedure for patients with preoperative diagnosis of ductal carcinoma in situ: risk factors for unsuspected invasive disease and for metastatic sentinel lymph nodes.

BACKGROUND: Occult invasive disease could be found at definitive histology in patients initially diagnosed with large ductal carcinoma in situ (DCIS). Sentinel lymph node (SLN) biopsy is a reliable and minimally invasive procedure providing axillary information and avoiding a second operation in this particular group of patients. The aim of our study was to assess the value of SLN biopsy in patients with large DCIS who are at highest risk for being upstaged to invasive carcinoma. PATIENTS AND METHODS: The study included 195 patients diagnosed with DCIS upon initial core biopsy and undergoing SLN biopsy. Many features were correlated with the presence of unsuspected invasive disease and positive SLN biopsy using univariate and multivariate analyses. RESULTS: Of the 110 patients with pure DCIS, seven patients (6%) had a metastatic lymph node; 31 patients (16%) were found to have invasive disease upon final histology. Univariate analysis of predictors of unsuspected invasive carcinoma showed that patients having a preoperative biopsy that indicated DCIS with microinvasion (DCISM) or large DCIS were at a higher risk of invasive carcinoma after histological examination of the operative specimen. Of the 31 patients who were upstaged to invasive carcinoma at final histology, seven patients (22%) had a positive SLN biopsy. The analysis of predictors of positive SLN in our study shows that diffuse DCIS requiring mastectomy is the main risk factor for SLN metastasis. CONCLUSION: There are no real predictive factors for invasive disease in patients with an initial diagnosis of DCIS or DCISM. Our study supports the value of SLN biopsy in patients with a preoperative DCISM biopsy or patients with a large pure DCIS biopsy requiring mastectomy.

[Accelerated partial breast irradiation using interstitial high dose rate brachytherapy: preliminary clinical and dosimetric results after 61 patients]. / Irradiation insterstitielle partielle et accélérée du sein de haut débit de dose: résultats préliminaires cliniques et dosimétriques sur 61 patientes.

PURPOSE: Among all the accelerated and partial breast irradiation (APBI) techniques, low then high dose rate, interstitial brachytherapy (HDIB) was the first to be used in this field. This study presents the preliminary clinical and dosimetric results of the APBI using HDIB, performed in Antoine Lacassagne Cancer Center of Nice. PATIENTS AND METHODS: From June 2004 to March 2008, 61 patients (37 primary tumors and 24 second conservative treatments after local recurrence) presenting with T1-2 pN0 non-lobular invasive breast carcinoma, underwent lumpectomy with sentinel lymph node dissection and intraoperative tube placement for HDIB. Dose distribution analysis, using dose-volume histograms, was achieved based on a postoperative CT scan. A comparative dosimetric study was performed between optimized (O) and non-optimized (NO) dose distribution. Then, based on conformal index calculation, a novel index was proposed taking into account not only the conformity but also the homogeneity of HDIB implant. An analysis of dose gradient impact on HDIB biological equivalence dose was also conducted. Statistical analysis used T test confirmed by Wilcoxon test for cohort including less than 30 patients. RESULTS: The comparative dosimetric analysis between O and NO dose distributions shown that conformity indexes (conformal index, conformal number, and D90%) were significantly increased after optimization. Improving conformity leads to increasing hyperdosage volumes (V150% and V200%). A new index named conformity and homogeneity index (CHI) including V150% values, modified the conformal index. A total dose of 34 Gy, delivered through HDIB in 10 fractions over five days was biologically equivalent to 41.93 Gy assuming alpha/beta = 4 Gy and 75.76 Gy if the dose gradient was considered in the calculation. CONCLUSIONS: HDIB is considered as one of the best IPAS technique. HDIB allows dose distribution optimization, skin spearing and accurate clinical target volume definition. Furthermore, HDIB dose gradient could play a key role for breast cancer local control.

[Ameloblastomas]. / Les améloblastomes.

OBJECTIVES: The aim of this work was to report on the clinical, radiological and histological characteristics of ameloblastomas concerning bone structures of the face, rare but not exceptional tumours, and to communicate our experience of their treatment. MATERIAL AND METHODS: The authors reexamined six recent cases of patients presenting with ameloblastoma at the centre Antoine Lacassagne in Nice. The diagnostic context, the treatment and the development of the disease are given in detail, emphasizing the frequency of local relapse of this histologically benign condition. RESULTS: The study of these cases confirmed the benefit of surgical treatment of ameloblastoma. The frequency of local relapse in the cases of close resection, leaving in place micro-foci, justifies enlarged intervention, which is often bone destructive. CONCLUSION: When the continuity of the bone is interrupted, in particular at the level of the mandible, and if the general condition of the patient permits, repair is preferable. In this situation, the procedure of choice is micro-anastomosis of the fibula.

Early versus late local recurrences after conservative treatment of breast carcinoma: differences in primary tumor characteristics and patient outcome.

OBJECTIVES: To investigate whether some aspects of patient or tumor characteristics influence the timing of local recurrence (LR) in breast cancer treated conservatively, and to assess the impact of the timing of LR on patient outcome. METHODS: A retrospective analysis was conducted on patients treated with conservative breast surgery followed by radiotherapy for breast carcinoma who developed LR. Out of 2,008 cases treated in our Institute between 1977 and 2002, 180 ipsilateral LR were observed. Of these, 46 LR were observed within 36 months after treatment, called early local recurrence (ELR), 44 developed between 37 and 60 months, called medium local recurrence (MLR), and 90 occurred after 60 months, called late local recurrence (LLR). Patient and tumor characteristics were analyzed in the 2 groups and compared. RESULTS: Primary tumors >20 mm were more frequently found in patients with ELR (31%) than in patients with LLR (17%, p = 0.047). Grade 3 tumors were more often encountered in patients with ELR than in patients with LLR (27 versus 7%, p = 0.0002). Patients with ELR more frequently had tumors with negative estrogen receptors than patients with LLR (37% versus 6%, p < 0.0001). There was no statistically significant difference in the axillary lymph node (LN) status between patients with ELR and those with LLR (35 and 23% of positive LN, respectively, p = 0.24). Tumor size, grade, LN status, hormone receptors and the timing of LR affected the specific survival (SS) from initial surgery. On multivariate analysis, only LN status and the timing of LR retained an independent prognostic value, with an odds ratio of 6.7 for ELR. After LR, the SS was also influenced by all of the above factors, and on multivariate analysis, LN status, hormone receptors and the timing of LR were independent predictors with an odds ratio of SS of 2.50 in case of ELR (p = 0.006). The 5-year SS after LR for ELR, MLR and LLR were 55.8, 74.8 and 79.5%, respectively. CONCLUSIONS: Unfavorable tumor characteristics such as big size, high grade, lack of hormone receptors, but not LN status, were associated with ELR. These findings suggest that patients with such aggressive tumor characteristics who do not recur early will have a lower risk of LLR than patients with more favorable factors.

[When should caution be used with regards to histopathologic findings of imaging-guided breast micro- and macro-biopsies?]. / Quand se méfier des résultats des micro et macrobiopsies guidées mammaires?

The development of imaging-guided biopsy techniques has considerably improved the early diagnosis of breast cancers following initial detection by screening. Nevertheless, in a small percentage of cases, histopathologic findings are unsatisfactory owing to false negative errors attributable to operator inexperience or inadequate sample material (this is especially true for microcalcifications with 20% underestimation rates for atypical hyperplasia); repeat biopsy is warranted in such situations. When a discrepancy exists with imaging findings and for cases of atypical epithelial hyperplasia, surgical excision is imperative so as not to overlook or underestimate a malignant lesion. Controversy continues concerning the best approach for radial scars (sclerosing ductal lesions), papillary lesions, atypical lobular hyperplasia and lobular carcinoma in situ: determination of which benign anomalies can merely be followed-up remains a problem. Better awareness of the limitations of percutaneous tissue sampling procedures should lead to refinement of the indications for these techniques and improvement of patient selection and thereby reduce delays in accurate diagnosis.

Immunophenotyping and metastatic localization of breast cancer.

Monoclonal antibody SM 92 is involved in the immunophenotype of gastrointestinal and liver cells, SM 43 in ovarian cells, and SM 13 in lung cells. Based on a study of 61 breast adenocarcinoma patients, we found that tumors reacting with SM 92 appear associated with liver metastases, SM 43 with ovarian metastases, and SM 13 with lung metastases. These associations are highly significant. They lend some support to the concept that tumor cells that metastasize tend to go to sites where cells normally have the same surface antigens.

Establishment, characterization, chemosensitivity, and radiosensitivity of two different cell lines derived from a human breast cancer biopsy.

In vitro culture of a human breast cancer biopsy fragment gave rise to two permanent cell lines, CAL 18 A and CAL 18 B, which were differentiated by both morphological and ultrastructural analysis. The karyotypic and growth properties of these two cell lines also differed, providing further evidence of cell heterogeneity within a given tumor. Both cell lines lost their hormone receptors in vitro. CAL 18 A cells grew in agar and were tumorigenic after inoculation into nude mice; neither of these properties was observed in CAL 18 B cells. The chemosensitivity of 12 antineoplastic drugs was assessed by a short-term assay, using inhibition of tritiated thymidine incorporation by the cells after contact with the drugs as the end point. Only a few drugs were active at moderate concentrations. The overall responses of both cell lines were similar. The cell survival curves, established by the colony method following a single dose of radiation, were also very similar, despite the greater heterogeneity of CAL 18 B cells. The two cell lines appear to be interrelated, since CAL 18 B cells were occasionally observed to emerge from CAL 18 A clones, suggesting that malignant cell redifferentiation may occur spontaneously in vitro.

Characterization of a new surface epitope specific for human epithelial cells defined by a monoclonal antibody and application to tumor diagnosis.

In an attempt to characterize the antigens attached to cells of a line established from a human squamous cell carcinoma of the tongue (CAL 27), BALB/c mice were immunized with whole CAL 27 cells; hybridomas were then produced using spleen cells of the animals and cells of an NS1 syngeneic myeloma. A hybridoma secreting a monoclonal antibody was obtained (CALAM 27); CALAM 27 was directed against an epitope attached to the CAL 27 cells. CALAM 27, IgG2a, reacted with a membrane antigen specific to all epithelial cells. After immunoprecipitation, this antigen corresponded to two bands (Mr 22,000 and 54,000). Reactivity disappeared when the tissue was embedded in paraffin but was conserved after fixation with acetone or methanol. This antigen was conserved for both benign and malignant epithelial cell pathologies. The action of CALAM 27 was tested on 80 samples of pleural effusions, ascites, and cerebrospinal fluid samples; after conventional cytological examinations, CALAM 27 failed to recognize either reactive mesothelial cells or meningothelial cells. In addition, the cell structure recognized by CALAM 27 is not found on certain lymphoid tissue cells. CALAM 27 also failed to react with small cell carcinoma of the lung. Its strictly epithelial specificity therefore permits its use for the diagnosis of micrometastases of carcinoma in ascites and cerebrospinal fluid, in pleural effusions, and in bone marrow. CALAM 27 may also prove useful in confirming diagnosis of pathologies suspected to be of epithelial origin.

[Role of imaging in the evaluation of axillary nodes and metastatic disease from breast carcinoma]. / Imagerie dans le bilan d'extension ganglionnaire et métastatique du cancer du sein.

Disease staging of patients with breast cancer is based on the probability of metastatic disease, the reliability of complementary examinations, and therapeutic possibilities, evaluated on a cost/benefit basis. For regional disease staging, nodal status can be assessed by ultrasound, and the value of this approach can be optimized by imaging-guided biopsies. Ultrasound examination of nodes upstream of the sentinel node allows determination of the utility of this node and the indications for axillary resection. Work-up of metastatic spread is performed only after evaluation of risk factors for metastasis. Prior to therapy, and in the absence of any clinical warning signs for resectable tumors, there are no indications for imaging, which is reserved solely for locally advanced tumors.