MRI in patients with a cerebral aneurysm clip; review of the literature and incident databases and recommendations for the Netherlands.

BACKGROUND: In the past ferromagnetic cerebral aneurysm clips that are contraindicated for Magnetic Resonance Imaging (MRI) have been implanted. However, the specific clip model is often unknown for older clips, which poses a problem for individual patient management in clinical care. METHODS: Literature and incident databases were searched, and a survey was performed in the Netherlands that identified time periods at which ferromagnetic and non-ferromagnetic clip models were implanted. Considering this information in combination with a national expert opinion, we describe an approach for risk assessment prior to MRI examinations in patients with aneurysm clips. The manuscript is limited to MRI at 1.5 T or 3 T whole body MRI systems with a horizontal closed bore superconducting magnet, covering the majority of clinical Magnetic Resonance (MR) systems. RESULTS: From the literature a list of ferromagnetic clip models was obtained. The risk of movement or rotation of the clip due to the main magnetic field in case of a ferromagnetic clip is the main concern. In the incident databases records of four serious incidents due to aneurysm clips in MRI were found. The survey in the Netherlands showed that from 2000 onwards, no ferromagnetic clips were implanted in Dutch hospitals. DISCUSSION: Recommendations are provided to help the MR safety expert assessing the risks when a patient with a cerebral aneurysm clip is referred for MRI, both for known and unknown clip models. This work was part of the development of a guideline by the Dutch Association of Medical Specialists.

Understanding and predicting the performance of passive heat and moisture exchangers using a numerical model.

BACKGROUND: To improve the understanding of the thermodynamics and performance of small passive hygroscopic Heat and Moisture Exchangers (HMEs), a computer model simulating HME function is required. METHODS: We developed a numerical HME model to calculate the HME's water and heat exchange. The model was tuned and verified with experimental data and validated by applying it to HME design variations. RESULTS: Verification of the model's results to the experimental data shows that the tuned model yields reliable results. The mass of the core, which determines the HME's total heat capacity, is the most important parameter influencing the performance of passive HMEs. CONCLUSIONS: Increasing the HME's diameter is an effective way to improve an HME, as it yields higher performance and lowers breathing resistance. HMEs intended for use in warm or dry climates should contain more and those for use in cold humid climates should contain less hygroscopic salt.

Adjustable breathing resistance for laryngectomized patients: Proof of principle in a novel heat and moisture exchanger cassette.

BACKGROUND: Due to the heat and moisture exchanger's (HME) breathing resistance, laryngectomized patients cannot always use an (optimal) HME during physical exercise. We propose a novel HME cassette concept with adjustable "bypass," to provide adjustment between different breathing resistances within one device. METHODS: Under standardized conditions, the resistance and humidification performance of a high resistance/high humidification HME (XM) foam in a cassette with and without bypass were compared to a lower resistance/lesser humidification HME (XF) foam in a closed cassette. RESULTS: With a bypass in the cassette, the resistance and humidification performance of XM foam were similar to those of XF foam in the closed cassette. Compared to XM foam in the closed cassette, introducing the bypass resulted in a 40% resistance decrease, whereas humidification performance was maintained at 80% of the original value. CONCLUSIONS: This HME cassette prototype allows adjustment between substantially different resistances while maintaining appropriate humidification performances.

Ex vivo humidifying capacity and patient acceptability of stoma cloths in laryngectomized individuals.

BACKGROUND: Heat and moisture exchangers (HMEs) improve respiratory function after laryngectomy, but there is virtually no information on the benefit of traditional stoma cloths or other covers. METHODS: Two sequential studies were performed: (1) an ex vivo test was used to compare the humidifying capacity of stoma cloths to other coverings; and (2) a 4-week randomized trial was then performed to assess patient acceptability of cloths both alone and with an HME (N = 18). RESULTS: The humidifying capacity of the coverings tested varied widely. For stoma cloths, a humidifying capacity of 13.7 mg/L was found to decrease to 8.5 mg/L if air-leaks around the cloth occurred. Patients who used HMEs disliked stoma cloths because they interfered with voicing, they became soiled more easily, and were less effective at reducing coughing and mucus production. CONCLUSION: Although less acceptable to patients who use an HME, stoma cloths do provide significant humidifying capacity and should be encouraged when HMEs are unavailable or inappropriate. © 2017 Wiley Periodicals, Inc. Head Neck 39: 921-931, 2017.

Water Uptake Performance of Hygroscopic Heat and Moisture Exchangers after 24-Hour Tracheostoma Application.

OBJECTIVE: After total laryngectomy, patients suffer from pulmonary complaints due to the shortcut of the upper airways that results in decreased warming and humidification of inspired air. Laryngectomized patients are advised to use a heat and moisture exchanger (HME) to optimize the inspired air. According to manufacturers' guidelines, these medical devices should be replaced every 24 hours. The aim of this study is to determine whether HMEs still function after 24-hour tracheostoma application. STUDY DESIGN: Assessment of residual water uptake capacity of used HMEs by measuring the difference between wet and dry core weight. SETTING: Tertiary comprehensive cancer center. SUBJECTS AND METHODS: Three hygroscopic HME types were tested after use by laryngectomized patients in long-term follow-up. Water uptake of 41 used devices (including 10 prematurely replaced devices) was compared with that of control (unused) devices of the same type and with a control device with a relatively low performance. RESULTS: After 24 hours, the mean water uptake of the 3 device types had decreased compared with that of the control devices. For only one type was this difference significant. None of the used HMEs had a water uptake lower than that of the low-performing control device. CONCLUSION: The water uptake capacity of hygroscopic HEMs is clinically acceptable although no longer optimal after 24-hour tracheostoma application. From a functional point of view, the guideline for daily device replacement is therefore justified.

Ex vivo water exchange performance and short-term clinical feasibility assessment of newly developed heat and moisture exchangers for pulmonary rehabilitation after total laryngectomy.

Laryngectomized patients suffer from respiratory complaints due to insufficient warming and humidification of inspired air in the upper respiratory tract. Improvement of pulmonary humidification with significant reduction of pulmonary complaints is achieved by the application of a heat and moisture exchanger (HME) over the tracheostoma. The aim of this study was to determine whether the new Provox HMEs (XM-HME and XF-HME) have a better water exchange performance than their predecessors (R-HME and L-HME, respectively; Atos Medical, Hörby, Sweden). The other aim was to assess the short-term clinical feasibility of these HMEs. The XM-HME and XF-HME were weighed at the end of inspiration and at the end of expiration at different breathing volumes produced by a healthy volunteer. The associations between weight changes, breathing volume and absolute humidity were determined using both linear and non-linear mixed effects models. Study-specific questionnaires and tally sheets were used in the clinical feasibility study. The weight change of the XM-HME is 3.6 mg, this is significantly higher than that of the R-HME (2.0 mg). The weight change of the XF-HME (2.0 mg) was not significantly higher than that of the L-HME (1.8 mg). The absolute humidity values of both XM- and XF-HME were significantly higher than that of their predecessors. The clinical feasibility study did not reveal any practical problems over the course of 3 weeks. The XM-HME has a significantly better water exchange performance than its predecessor (R-HME). Both newly designed HMEs did succeed in the clinical feasibility study.

Ex vivo assessment and validation of water exchange performance of 23 heat and moisture exchangers for laryngectomized patients.

BACKGROUND: Breathing through a tracheostoma results in insufficient warming and humidification of the inspired air. This loss of air conditioning, especially humidification, can be partially restored with the application of a heat and moisture exchanger (HME) over the tracheostoma. For medical professionals, it is not easy to judge differences in water exchange performance of various HMEs owing to the lack of universal outcome measures. This study has three aims: assessment of the water exchange performance of commercially available HMEs for laryngectomized patients, validation of these results with absolute humidity outcomes, and assessment of the role of hygroscopic salt present in some of the tested HMEs. METHODS: Measurements of weight and absolute humidity at end inspiration and end expiration at different breathing volumes of a healthy volunteer were performed using a microbalance and humidity sensor. Twenty-three HMEs from 6 different manufacturers were tested. Associations were determined between core weight, weight change, breathing volume, and absolute humidity, using both linear and nonlinear mixed effects models. RESULTS: Water exchange of the 23 HMEs at a breathing volume of 0.5 L varies between 0.5 and 3.6 mg. Both water exchange and wet core weight correlate strongly with the end-inspiratory absolute humidity values (r2 =0.89/0.87). Hygroscopic salt increases core weight. CONCLUSIONS: The 23 tested HMEs for laryngectomized patients show wide variation in water exchange performance. Water exchange correlates well with the end-inspiratory absolute humidity outcome, which validates the ex vivo weight change method. Wet core weight is a predictor of HME performance. Hygroscopic salt increases the weight of the core material. The results of this study can help medical professionals to obtain a more founded opinion about the performance of available HMEs for pulmonary rehabilitation in laryngectomized patients, and allow them to make an informed decision about which HME type to use.

A novel, simplified ex vivo method for measuring water exchange performance of heat and moisture exchangers for tracheostomy application.

BACKGROUND: Breathing through a tracheostomy results in insufficient warming and humidification of inspired air. This loss of air-conditioning can be partially compensated for with the application of a heat and moisture exchanger (HME) over the tracheostomy. In vitro (International Organization for Standardization [ISO] standard 9360-2:2001) and in vivo measurements of the effects of an HME are complex and technically challenging. The aim of this study was to develop a simple method to measure the ex vivo HME performance comparable with previous in vitro and in vivo results. METHODS: HMEs were weighed at the end of inspiration and at the end of expiration at different breathing volumes. Four HMEs (Atos Medical, Hörby, Sweden) with known in vivo humidity and in vitro water loss values were tested. The associations between weight change, volume, and absolute humidity were determined using both linear and non-linear mixed effects models. RESULTS: The rating between the 4 HMEs by weighing correlated with previous intra-tracheal measurements (R(2) = 0.98), and the ISO standard (R(2) = 0.77). CONCLUSIONS: Assessment of the weight change between end of inhalation and end of exhalation is a valid and simple method of measuring the water exchange performance of an HME.

Reducing the throughput time of the diagnostic track involving CT scanning with computer simulation.

INTRODUCTION: To examine the use of computer simulation to reduce the time between the CT request and the consult in which the CT report is discussed (diagnostic track) while restricting idle time and overtime. METHODS: After a pre implementation analysis in our case study hospital, by computer simulation three scenarios were evaluated on access time, overtime and idle time of the CT; after implementation these same aspects were evaluated again. Effects on throughput time were measured for outpatient short-term and urgent requests only. CONCLUSION: The pre implementation analysis showed an average CT access time of 9.8 operating days and an average diagnostic track of 14.5 operating days. Based on the outcomes of the simulation, management changed the capacity for the different patient groups to facilitate a diagnostic track of 10 operating days, with a CT access time of 7 days. After the implementation of changes, the average diagnostic track duration was 12.6 days with an average CT access time of 7.3 days. The fraction of patients with a total throughput time within 10 days increased from 29% to 44% while the utilization remained equal with 82%, the idle time increased by 11% and the overtime decreased by 82%. The fraction of patients that completed the diagnostic track within 10 days improved with 52%. Computer simulation proved useful for studying the effects of proposed scenarios in radiology management. Besides the tangible effects, the simulation increased the awareness that optimizing capacity allocation can reduce access times.

Cine MRI of swallowing in patients with advanced oral or oropharyngeal carcinoma: a feasibility study.

Treatment of oral and oropharyngeal cancer may cause dysphagia. Purpose is to examine whether cine magnetic resonance imaging (MRI) yields additional information compared to standard examination in the evaluation of posttreatment dysphagia and mobility of oral and oropharyngeal structures. Thirty-four cine MRIs were made in 23 patients with advanced oral and oropharyngeal cancer, consisting of an MR image every 800 ms during swallowing which is compared to videofluoroscopy and quality of life questionnaires. A scoring system was applied to assess mobility on cine MR and videofluoroscopy leading to a score ranging from 9 to 17. Cine MRI of the swallowing in a midsagittal plane visualized the tumor (if located in the same plane), important anatomic structures and surgical reconstructions. Posttreatment mobility on cine MRI and videofluoroscopy was significantly diminished compared to pretreatment, mean pretreatment cine MRI score was 10.8 and posttreatment 12.4 (p = 0.017). Impaired mobility on cine MRI was significantly correlated to more swallowing problems (Spearman's correlation coefficient 0.73, p = 0.04), on videofluoroscopy not. Cine MRI is a promising new technique as an adjunct to standard examinations for evaluation of swallowing in patients with oral and oropharyngeal cancer. Cine MRI directly visualizes the dynamics of swallowing and allows evaluation of pre- and posttreatment differences. Abnormal findings are significantly correlated with subjective swallowing complaints of patients.

Endotracheal temperature and humidity in laryngectomized patients in a warm and dry environment and the effect of a heat and moisture exchanger.

BACKGROUND: This study was designed to assess endotracheal climate in laryngectomized patients in a warm and dry environment and the effects of a heat and moisture exchanger (HME). METHODS: Endotracheal temperature and humidity were measured in 11 laryngectomized patients with a regularly used HME (Provox Normal HME; R-HME), an HME with antimicrobial filter (Provox Micron HME; F-HME), and without HME (open stoma). Measurements were performed at 32°C, 34°C, and 38°C (<25% relative humidity). RESULTS: Both R-HME and F-HME increased end-inspiratory humidity (AH(insp)) equally (range, 3.4 to 5.6 mg H(2)O/L). The R-HME has a cooling effect on end-inspiratory temperature (T(insp)), which is similar for all tested environmental conditions (-3.8°C); F-HME decreases T(insp) less (range, -1.3 to -0.6°C). CONCLUSIONS: In a warm and dry environment, both R- and F-HME significantly cool and humidify inspired air. Therefore, consistent use of an HME under these climate conditions is also probably clinically beneficial.

Magnetic resonance imaging response monitoring of breast cancer during neoadjuvant chemotherapy: relevance of breast cancer subtype.

PURPOSE: To evaluate the relevance of breast cancer subtypes for magnetic resonance imaging (MRI) markers for monitoring of therapy response during neoadjuvant chemotherapy (NAC). PATIENTS AND METHODS: MRI examinations were performed in 188 women before and during NAC. MRI interpretation included lesion morphology at baseline, changes in morphology, size, and contrast uptake kinetics (initial and late enhancement). By using immunohistochemistry, tumors were divided into three subtypes: triple negative, human epidermal growth factor receptor 2 (HER2) positive, and estrogen receptor (ER) positive/HER2 negative. Tumor response was assessed dichotomously (ie, presence or absence of residual tumor in the surgical specimen). Complementary, a continuous scale assessment was used (the breast response index [BRI], representing the relative change in tumor stage). Multivariate regression analysis and receiver operating characteristic analysis were employed to establish significant associations. RESULTS: Residual tumor at pathology was present in 31 (66%) of 47 triple-negative tumors, 23 (61%) of 38 HER2-positive tumors, and 96 (93%) of 103 ER-positive/HER2-negative tumors. Multivariate analysis of residual disease showed significant associations between breast cancer subtype and MRI (area under the curve [AUC], 0.84; P < .001). BRI also showed significant correlation among breast cancer subtype, MRI, and age (Pearson's r = 0.465; P < .001). In subset analysis, this was only significant for triple-negative tumors (P < .001) and HER2-positive tumors (P < .05). Residual tumor after NAC in the triple-negative and HER2-positive group is significantly associated with the change in largest diameter of late enhancement during NAC (AUC, 0.76; P < .001). No associations were found for ER-positive/HER2-negative tumors. CONCLUSION: MRI during NAC to monitor response is effective in triple-negative or HER2-positive disease but is inaccurate in ER-positive/HER2-negative breast cancer.

Heat and moisture exchange capacity of the upper respiratory tract and the effect of tracheotomy breathing on endotracheal climate.

BACKGROUND: The aim of this study was to assess the heat and moisture exchange (HME) capacity of the upper respiratory tract and the effect of tracheotomy breathing on endotracheal climate in patients with head and neck cancer. METHODS: We plotted the subglottic temperature and humidity measurements in 10 patients with head and neck cancer with a temporary precautionary tracheotomy during successive 10-minute periods of nose, mouth, and tracheotomy breathing in a randomized sequence. RESULTS: End-inspiratory temperatures of nose, mouth, and tracheotomy breathing were 31.1, 31.3, and 28.3°C, respectively. End-inspiratory humidity measurements of nose, mouth, and tracheotomy breathing were 29.3, 28.6, and 21.1 mgH2O/L, respectively. There was a trend toward lower end-inspiratory humidity in patients with radiotherapy or with large surgery-induced oropharyngeal mucosal defects, whereas temperatures were similar. CONCLUSION: This study gives objective information about the HME capacity of the upper respiratory tract in patients with head and neck cancer with precautionary tracheotomy, and thus provides target values for HMEs for laryngectomized and tracheotomized patients.

BRCA1-associated breast cancers present differently from BRCA2-associated and familial cases: long-term follow-up of the Dutch MRISC Screening Study.

PURPOSE: The Dutch MRI Screening Study on early detection of hereditary breast cancer started in 1999. We evaluated the long-term results including separate analyses of BRCA1 and BRCA2 mutation carriers and first results on survival. PATIENTS AND METHODS: Women with higher than 15% cumulative lifetime risk (CLTR) of breast cancer were screened with biannual clinical breast examination and annual mammography and magnetic resonance imaging (MRI). Participants were divided into subgroups: carriers of a gene mutation (50% to 85% CLTR) and two familial groups with high (30% to 50% CLTR) or moderate risk (15% to 30% CLTR). RESULTS: Our update contains 2,157 eligible women including 599 mutation carriers (median follow-up of 4.9 years from entry) with 97 primary breast cancers detected (median follow-up of 5.0 years from diagnosis). MRI sensitivity was superior to that of mammography for invasive cancer (77.4% v 35.5%; P<.00005), but not for ductal carcinoma in situ. Results in the BRCA1 group were worse compared to the BRCA2, the high-, and the moderate-risk groups, respectively, for mammography sensitivity (25.0% v 61.5%, 45.5%, 46.7%), tumor size at diagnosis≤1 cm (21.4% v 61.5%, 40.9%, 63.6%), proportion of DCIS (6.5% v 18.8%, 14.8%, 31.3%) and interval cancers (32.3% v 6.3%, 3.7%, 6.3%), and age at diagnosis younger than 30 years (9.7% v 0%). Cumulative distant metastasis-free and overall survival at 6 years in all 42 BRCA1/2 mutation carriers with invasive breast cancer were 83.9% (95% CI, 64.1% to 93.3%) and 92.7% (95% CI, 79.0% to 97.6%), respectively, and 100% in the familial groups (n=43). CONCLUSION: Screening results were somewhat worse in BRCA1 mutation carriers, but 6-year survival was high in all risk groups.

A self-assembled multimodal complex for combined pre- and intraoperative imaging of the sentinel lymph node.

Specific removal of the sentinel lymph node (SLN) during breast cancer surgery presents physicians with the opportunity to detect early metastatic disease. To increase the accuracy of intraoperative SLN detection, new methods with higher sensitivity and specificity are required. We have quantitatively compared conventional preoperative lymphoscintigraphy with albumin radiocolloids ((99m)Tc-NanoColl) with optical intraoperative guidance using the near infrared dye indocyanine green (ICG) in an orthotopic mouse model for metastatic breast cancer. Furthermore, we have applied a self-assembled multimodal complex, in which ICG is non-covalently bound to the albumin radiocolloid, to attain identical dynamics of the radioactive and optical components. The SLN specificity of the multimodal complex is similar to conventional lymphoscintigraphy, while the fluorescent signal-to-noise ratio is improved by 86% compared to ICG alone. In addition, the multimodal complex permits scintigraphic validation of the fluorescent findings. The multimodal ICG-(99m)Tc-NanoColl complex can be used both for lymphoscintigraphy by preoperative single photon emission computed tomography/computed tomography and for surgical navigation by intraoperative fluorescence imaging.

Optimizing the colloid particle concentration for improved preoperative and intraoperative image-guided detection of sentinel nodes in prostate cancer.

PURPOSE: Lymphatic mapping for prostate cancer can be used to determine therapeutic strategies. Sentinel node visualization requires sufficient nodal tracer uptake. We evaluated the effect of an increase in particle concentration on preoperative and intraoperative sentinel node depiction. METHODS: Enrolled in the study were 50 consecutive patients with prostate cancer. The first 25 patients (group A) received nanocolloid with standard labelling (0.4 ml (99m)Tc per 0.1 mg nanocolloid). The last 25 patients (group B) received nanocolloid with a reduced labelling dilution volume (0.4 ml (99m)Tc per 0.2 mg nanocolloid). The aimed injected volume and dosage were the same for both groups (225 MBq in 0.4 ml). Intratumoral tracer injection was followed by planar lymphoscintigraphy (15 min and 2 h), SPECT/CT and laparoscopic sentinel lymphadenectomy. Lymph node visualization was evaluated using a four-point scoring system (0 nonvisualization to 3 intense visualization) and count quantification on the 2-h anterior lymphoscintigram. In addition to the gamma ray detection probe, a portable gamma camera was used for intraoperative sentinel node visualization. RESULTS: Preoperative visualization in group A was 88% (mean 2.0 sentinel nodes per patient) versus 100% in group B (mean 2.6 sentinel nodes per patient). Visualization scores (p=0.008), total counts (p=0.001) and maximum counts per pixel (p=0.034) in the sentinel nodes were significantly better in group B. This also led to more efficient intraoperative detection of the sentinel nodes with the portable gamma camera (84% in group A versus 100% in group B). CONCLUSION: Enhancement of the particle concentration may lead to significant improvement in sentinel node visualization and intraoperative localization in patients with prostate cancer. Further research regarding optimization of radiotracer labelling by changing the particle concentration is warranted.

Influence of breathing resistance of heat and moisture exchangers on tracheal climate and breathing pattern in laryngectomized individuals.

BACKGROUND: The aim of this study was to determine the influence of breathing resistance of heat and moisture exchangers (HMEs) on endotracheal climate and breathing pattern. METHODS: Endotracheal temperature and humidity and tidal volumes were measured in 11 laryngectomized patients with a regularly used HME with "standard" breathing resistance (Provox Normal HME; R-HME), a low breathing-resistance HME (Provox HiFlow HME; L-HME), and without HME. RESULTS: Both R-HME and L-HME increased end-inspiratory humidity (+5.8 and 4.7 mgH(2)O/L, respectively), decreased end-inspiratory temperature (-1.6 and -1.0 degrees C, respectively), and prolonged the exhalation breath length to approximately 0.5 seconds. The R-HME significantly enlarged tidal volumes (0.07 L; p < .05). CONCLUSIONS: Both HMEs significantly improve tracheal climate. The R-HME has better moistening properties and a small but significant positive effect on tidal volume. Therefore, if the higher resistance is tolerated, the R-HME is the preferred pulmonary rehabilitation device. The L-HME is indicated if lower breathing resistance is required.

Short-term endotracheal climate changes and clinical effects of a heat and moisture exchanger with an integrated electrostatic virus and bacterial filter developed for laryngectomized individuals.

CONCLUSION: Both the regularly used heat and moisture exchanger (R-HME) and the HME with both an antimicrobial and hygroscopic element (F-HME) are effective moisture exchangers. The antimicrobial filter of the F-HME acts as a heat exchanger. The external features of the F-HME were experienced as inconvenient, but decreased sputum production was reported as well. OBJECTIVES: Recently an HME with an integrated antimicrobial filter has become available for use in laryngectomized patients. The purpose of this study was to assess its short-term endotracheal climate changes and feasibility in daily practice. METHODS: Endotracheal temperature and humidity were successfully measured in 13 laryngectomized patients (2652 analysed full breaths), during 10 min rest-breathing with the R-HME, with an F-HME and without HME in a randomized sequence. Additionally, a 3 week prospective clinical feasibility trial was conducted in 17 laryngectomized patients. RESULTS: Both R-HME and F-HME increase endotracheal minimum humidity values (5.8 and 4.7 mgH(2)O/L, respectively; p < 0.0001). Compared with open stoma breathing, in contrast to the R-HME, the F-HME increases both end-inspiratory and end-expiratory temperature values (1.1 degrees C, and 0.6 degrees C, respectively). After the 3-week clinical feasibility trial, one patient dropped out; 11 patients (11/16 = 69%) disliked the larger design of the F-HME and all patients reported less optimal airtight occlusion. Five patients (5/16 = 31%) reported remarkably decreased sputum production.