Structural similarity analysis of midfacial fractures-a feasibility study.

The structural similarity index metric is used to measure the similarity between two images. The aim here was to study the feasibility of this metric to measure the structural similarity and fracture characteristics of midfacial fractures in computed tomography (CT) datasets following radiation dose reduction, iterative reconstruction (IR) and deep learning reconstruction. Zygomaticomaxillary fractures were inflicted on four human cadaver specimen and scanned with standard and low dose CT protocols. Datasets were reconstructed using varying strengths of IR and the subsequently applying the PixelShine™ deep learning algorithm as post processing. Individual small and non-dislocated fractures were selected for the data analysis. After attenuating the osseous anatomy of interest, registration was performed to superimpose the datasets and subsequently to measure by structural image quality. Changes to the fracture characteristics were measured by comparing each fracture to the mirrored contralateral anatomy. Twelve fracture locations were included in the data analysis. The most structural image quality changes occurred with radiation dose reduction (0.980036±0.011904), whilst the effects of IR strength (0.995399±0.001059) and the deep learning algorithm (0.999996±0.000002) were small. Radiation dose reduction and IR strength tended to affect the fracture characteristics. Both the structural image quality and fracture characteristics were not affected by the use of the deep learning algorithm. In conclusion, evidence is provided for the feasibility of using the structural similarity index metric for the analysis of structural image quality and fracture characteristics.

Iterative reconstruction and deep learning algorithms for enabling low-dose computed tomography in midfacial trauma.

OBJECTIVES: The objective of this study was to quantitatively assess the image quality of Advanced Modeled Iterative Reconstruction (ADMIRE) and the PixelShine (PS) deep learning algorithm for the optimization of low-dose computed tomography protocols in midfacial trauma. STUDY DESIGN: Six fresh frozen human cadaver head specimens were scanned by computed tomography using both standard and low-dose scan protocols. Three iterative reconstruction strengths were applied to reconstruct bone and soft tissue data sets and these were subsequently applied to the PS algorithm. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated for each data set by using the image noise measurements of 10 consecutive image slices from a standardized region of interest template. RESULTS: The low-dose scan protocol resulted in a 61.7% decrease in the radiation dose. Radiation dose reduction significantly reduced, and iterative reconstruction and the deep learning algorithm significantly improved, the CNR for bone and soft tissue data sets. The algorithms improved image quality after substantial dose reduction. The greatest improvement in SNRs and CNRs was found using the iterative reconstruction algorithm. CONCLUSION: Both the ADMIRE and PS algorithms significantly improved image quality after substantial radiation dose reduction.

Functional Swallowing Units (FSUs) as organs-at-risk for radiotherapy. PART 1: Physiology and anatomy.

BACKGROUND AND PURPOSE: When optimising radiotherapy treatments today, the pharyngeal constrictor muscles and the larynx are usually regarded as the swallowing organs at risk (SWOARs). The purpose of this study was to identify and describe additional, previously undefined groups of muscles (functional units) involved in crucial components of swallowing (hyolaryngeal elevation (HLE), tongue base retraction (TBR) and tongue motion), and to emphasise their relevance in radiation-induced dysphagia. MATERIAL AND METHODS: Based on available literature on human anatomy and swallowing physiology, the functional units of muscles involved in HLE, TBR and tongue motion have been identified and described. RESULTS AND CONCLUSION: Functional swallowing units (FSUs) were defined as groups of swallowing muscles sharing their function, that are in close proximity to each other. Seven FSUs involved in HLE, TBR and tongue motion were identified: floor of mouth, thyrohyoid muscles, posterior digastric/stylohyoid muscles complex, longitudinal pharyngeal muscles, hyoglossus/styloglossus muscles complex, genioglossus muscles, intrinsic tongue muscles. The swallowing physiology and anatomy of the FSUs described in this paper will lead to a greater understanding of radiation-induced dysphagia mechanisms and, consequently, to an improvement in the development of swallowing sparing strategies. This article (PART 1) serves as the theoretical foundation for a subsequent article (PART 2), which provides detailed delineation guidelines for FSUs.

Functional Swallowing Units (FSUs) as organs-at-risk for radiotherapy. PART 2: Advanced delineation guidelines for FSUs.

BACKGROUND AND PURPOSE: In a separate article (PART 1), a rationale and explanation of the physiology-and-anatomy-based concept of Functional Swallowing Units (FSUs) was presented. FSUs are swallowing muscles not included in the set of commonly defined swallowing organs at risk (SWOARs). They are involved in three crucial swallowing components: hyolaryngeal elevation (HLE), tongue base retraction (TBR) and tongue motion. This paper is a continuation of PART 1 and it provides detailed computed tomography (CT)-based delineation guidelines for FSUs, which presumably are also at risk of radiation-induced dysphagia. MATERIAL AND METHODS: Following analysis of swallowing physiology and human anatomy, presented in PART 1, CT-based delineation guidelines for defined FSUs were created. Delineation was performed by the first author and revised by a panel of experts. RESULTS AND CONCLUSIONS: Detailed delineation guidelines are presented for seven FSUs involved in HLE, TBR and tongue motion. The guidelines are supplemented by CT and MRI-based exemplary illustrations and complete CT/MRI-based delineation atlases (available online). This paper provides information essential to the implementation of the FSU concept in radiation practice, and supports uniform contouring, data collection and further improvement of swallowing sparing radiation-based strategies.

The interobserver agreement in the detection of recurrent HNSCC using MRI including diffusion weighted MRI.

INTRODUCTION: For the detection of local recurrences of head and neck squamous cell carcinomas (HNSCC) after (chemo)radiation, diagnostic imaging is generally performed. Diffusion weighted magnetic resonance imaging (DW-MRI) has been proven to be able to adequately diagnose the presence of cancer. However evaluation of DW-MR images for recurrences is difficult and could be subject to individual interpretation. AIM: To determine the interobserver agreement, intraobserver agreement and influence of experience of radiologists in the assessment of DW-MRI in patients clinically suspected of local recurrent HNSCC after (chemo)radiation. METHODS: Ten experienced head and neck radiologists assessed follow-up MRI including DW-MRI series of 10 patients for the existence of local recurrence on a two point decision scale (local recurrence or local control). Patients were clinically suspected for a recurrence of laryngeal (n = 3), hypopharyngeal (n = 3) or oropharyngeal (n = 4) cancer after (chemo)radiation with curative intent. Fleiss' and Cohen's Kappa were used to determine interobserver agreement and intraobserver agreement, respectively. RESULTS: Interobserver agreement was κ = 0.55. Intraobserver agreement was κ = 0.80. Prior experience within the field of radiology and with DW-MRI had no significant influence on the scoring. CONCLUSION: For the assessment of HNSCC recurrence after (chemo)radiation by DW-MRI, moderate interobserver agreement and substantial intraobserver agreement was found.

Optimisation of three-dimensional lower jaw resection margin planning using a novel Black Bone magnetic resonance imaging protocol.

BACKGROUND: MRI is the optimal method for sensitive detection of tumour tissue and pre-operative staging in oral cancer. When jawbone resections are necessary, the current standard of care for oral tumour surgery in our hospital is 3D virtual planning from CT data. 3D printed jawbone cutting guides are designed from the CT data. The tumour margins are difficult to visualise on CT, whereas they are clearly visible on MRI scans. The aim of this study was to change the conventional CT-based workflow by developing a method for 3D MRI-based lower jaw models. The MRI-based visualisation of the tumour aids in planning bone resection margins. MATERIALS AND FINDINGS: A workflow for MRI-based 3D surgical planning with bone cutting guides was developed using a four-step approach. Key MRI parameters were defined (phase 1), followed by an application of selected Black Bone MRI sequences on healthy volunteers (phase 2). Three Black Bone MRI sequences were chosen for phase 3: standard, fat saturated, and an out of phase sequence. These protocols were validated by applying them on patients (n = 10) and comparison to corresponding CT data. The mean deviation values between the MRI- and the CT-based models were 0.63, 0.59 and 0.80 mm for the three evaluated Black Bone MRI sequences. Phase 4 entailed examination of the clinical value during surgery, using excellently fitting printed bone cutting guides designed from MRI-based lower jaw models, in two patients with oral cancer. The mean deviation of the resection planes was 2.3 mm, 3.8 mm for the fibula segments, and the mean axis deviation was the fibula segments of 1.9°. CONCLUSIONS: This study offers a method for 3D virtual resection planning and surgery using cutting guides based solely on MRI imaging. Therefore, no additional CT data are required for 3D virtual planning in oral cancer surgery.

Viable tumor in salvage neck dissections in head and neck cancer: Relation with initial treatment, change of lymph node size and human papillomavirus.

OBJECTIVES: To identify predictive factors for the presence of viable tumor and outcome in head and neck cancer patients who undergo therapeutic salvage neck dissections. MATERIALS AND METHODS: Retrospective analysis of 76 salvage neck dissections after radiotherapy alone (n = 22), radiotherapy in combination with carboplatin/5-fluorouracil (n = 42) or with cetuximab (n = 12). RESULTS: Viable tumor was detected in 41% of all neck dissections. Univariate analysis revealed initial treatment with radiotherapy without systemic therapy (OR 6.93, 95%CI: 2.28-21.07, p < .001), increased lymph node size after initial treatment compared to pretreatment CT scan (OR 20.48, 95%CI: 2.46-170.73, p = .005), more extensive neck dissections (OR 8.40, 95%CI: 2.94-23.98, p < .001), and human papillomavirus negative cancer (OR 4.22, 95%CI: 1.10-16.22, p = .036) as predictors of viable tumor. Patients with decreased or stable, but persistently enlarged lymph node size after chemoradiation had a significantly lower chance of viable tumor (OR 0.15, 95%CI: 0.05-0.41, p < .001). Disease-specific 5-year survival was 34% in case of viable tumor, and 78% when no viable tumor was found (p < .001). CONCLUSIONS: Viable tumor in salvage neck dissections is associated with reduced survival. Radiotherapy alone, human papillomavirus negative cancer and increase in lymph node size, are associated with viable tumor in salvage neck dissections. In case of decreased or stable lymph node size after chemoradiation, watchful waiting could be considered.

Localization of parathyroid adenomas using 11C-methionine pet after prior inconclusive imaging.

PURPOSE: Minimally invasive parathyroidectomy (MIP) is the recommended treatment in primary hyperparathyroidism (pHPT) for which accurate preoperative localization is essential. The current imaging standard consists of cervical ultrasonography (cUS) and MIBI-SPECT/CT. 11C-MET PET/CT has a higher resolution than MIBI-SPECT/CT. The aim of this study was to determine the diagnostic performance of 11C-MET PET/CT after initial inconclusive or negative localization. METHODS: We performed a retrospective single center cohort study of patients with pHPT undergoing parathyroid surgery after prior negative imaging and later localization by means of 11C-MET PET/CT between 2006 and 2014. Preoperative localization by 11C-MET PET/CT was compared with later surgical localization, intraoperative quick PTH (IOPTH), duration of surgery, histopathology, and follow-up data. Also, differences in duration of surgery between the groups with and without correct preoperative localization were analyzed. RESULTS: In 18/28 included patients a positive 11C-MET-PET/CT result corresponded to the surgical localized adenoma (64%). In 3/28 patients imaging was false positive and no adenoma was found. In 7/28 patients imaging was false negative at the side of the surgically identified adenoma. Sensitivity of 11C-MET PET/CT was 72% (18/25). Duration of surgery of correctly localized patients was significantly shorter compared to falsely negative localized patients (p = 0.045). CONCLUSION: In an intention to treat 11C-MET-PET/CT correctly localized the parathyroid adenoma in 18/28 (64%) patients, after previous negative imaging. A preoperatively correct localized adenoma leads to a more focused surgical approach (MIP) potentially reducing duration of surgery and potentially healthcare costs.

[Do not always puncture a thyroid nodule]. / Niet altijd prikken in een schildkliernodus.

The incidence of thyroid cancer is increasing, especially the papillary subtype. This increase can be mainly attributed to the detection of small - mostly indolent - papillary thyroid cancers as a consequence of the higher sensitivity of diagnostic techniques and the more frequent use of diagnostic applications. Two patients are described with (non-)palpable thyroid nodules to illustrate the risk of overdiagnostics and overtreatment. A thyroid incidentaloma detected on ultrasound, CT or MRI does not require further diagnostic procedures as standard. The pros and cons of diagnostic procedures must be discussed in a multidisciplinary team.