Evaluation of Post-Swallow Residue with Visual Analysis of Swallowing Efficiency and Safety in Patients with Idiopathic Parkinson's Disease.

Objectives: Dysphagia is common in idiopathic Parkinson's disease (IPD) and is associated with impairments in both swallowing safety and swallowing efficiency. The goals of this study were to define post-swallow residue patterns in people with IPD and describe pathophysiological endoscopic findings affecting residue accumulation. Methods: This was a prospective single-blinded cross-sectional cohort study of patients with the diagnosis of IPD recruited from a Movement Disorder Clinic. Clinical variables included patient age, cognitive function, and measures of disease severity, and laryngoscopic examinations with a flexible endoscopic evaluation of swallowing (FEES) were completed for each patient. Visual Analysis of Swallowing Efficiency and Safety (VASES) was used to analyze FEES. Post-swallow residue outcomes and non-residue endoscopic outcomes including the Bowing index, Penetration Aspiration Scale (PAS) score, premature leakage, and build-up phenomenon were evaluated. Multiple regression models were used to evaluate factors affecting the residue at different anatomic levels. Results: Overall 53 patients completed the study. The multiple regression analyses showed a relation between (1) the presence of residue at the level of oropharynx and epiglottis with premature leakage, (2) the presence of residue at the level of the laryngeal vestibule and vocal folds with build-up phenomenon, and (3) the presence of residue at the level of the hypopharynx, laryngeal vestibule, and subglottis with airway invasion. Conclusion: Residue pattern during FEES is associated with specific swallow dysfunctions in IPD. Using residue localization and quantification may be a helpful tool in assessing the impact of targeted swallowing interventions in patients with IPD and dysphagia.

Carcinoma of the posterior wall of the hypopharynx: surgical treatment with larynx preservation.

INTRODUCTION: Posterior pharyngeal wall is the most rare subsite for hypopharyngeal carcinomas. Because of its rarity, there are few studies published in the literature specifically concerning posterior pharyngeal wall carcinoma. OBJECTIVES: To report our functional results in patients with the carcinoma of the posterior wall of the hypopharynx after surgical treatment by resection via a lateral or infrahyoid pharyngotomy approach, with the preservation of the larynx and reconstruction with a radial forearm free flap. METHODS: The study included 10 patients who underwent surgery for a carcinoma of the posterior wall of the hypopharynx over a 6 year period. The associated postoperative morbidity was investigated and functional results were analyzed. RESULTS: Nine patients had T3 lesions and one patient had a T2 lesion. The preferred approach to access the hypopharynx was a lateral pharyngotomy in 5 patients and lateral pharyngotomy combined with infrahyoid pharyngotomy in 5 patients with superior extension to oropharynx. The pharyngeal defects were reconstructed successfully with radial forearm free flaps. Four patients received adjuvant radiotherapy only, and 4 patients with N2b and N2c neck diseases received adjuvant chemoradiotherapy. The mean duration of hospitalization was 15.6 days (range, 10-21 days). All patients achieved oral intake in a median time of 74 days (range, 15-180). Decannulation was achieved in all patients and the median time for decannulation was 90 (range, 21-300 days). The mean followup duration was 38.3 months (range, 10-71 months) and 8 patients survived. One patient died due to regional recurrence in the retropharyngeal lymph nodes and 1 patient died due to systemic metastasis. CONCLUSION: Primary surgery is still a very effective treatment modality for the carcinoma of the posterior wall of the hypopharynx and does not permanently compromise the swallowing and laryngeal functions if pharyngeal reconstruction is performed with a free flap.

Genotype Distribution and Prevalence of Human Papillomavirus in Head and Neck Cancer Samples from Istanbul, Turkey.

Human papillomavirus (HPV)-associated tumors account for a significant proportion of head and neck squamous cell carcinomas (HNSCC) in developed countries. In recent years, there has been a rise of HPV infections associated with HNSCC, especially HPV16, which is the most commonly detected type in oral and oropharyngeal cancers. To investigate the frequency of HPV-driven HNSCC among patients living in Turkey, HPV DNA positivity and p16INK4A expression were assessed in primary tumor biopsies (n = 106). Eighteen out of one hundred and six (19%) HNSCC tumors showed p16INK4A overexpression, and 26/106 cases (24.5%) were positive for HPV DNA. Sixteen out of twenty-six samples were positive for both HPV DNA and p16INK4A staining. HPV16 could be isolated from 22/26 samples (84.6%) and was found to be the most frequently detected HPV type. This study represents the largest cohort of Turkish patients with HNSCC characterized according to HPV status and p16INK4A expression. Our data suggest that HPV16 infection, along with smoking, contribute to the development of HNSCC.

Free Flap Reconstruction of the Head and Neck Region: A Series of 127 Flaps Performed by Otolaryngologists.

OBJECTIVE: To determine flap success rate and complications in patients who underwent microvascular free tissue reconstruction after major head and neck ablative surgery and to report the improvement in the results. METHODS: Medical records of 124 patients who were operated on in 2012 to 2019 were retrospectively reviewed. Indications for different free flap types, success rates and re-exploration rates, donor site morbidities, and reasons for flap loss were analyzed. Patients were divided into two groups to identify the effects of the anticoagulant and the antiaggregant treatments on postoperative results. RESULTS: There were 127 flaps in 124 patients, including two different free flaps each in three patients that were harvested and used in the same surgical session. Of the total 127 flaps, 82 (64.6%) were radial forearm flaps, 39 (30.7%) were fibula flaps, and 6 (4.7) were rectus abdominis flaps. Four patients were re-explored for flap perfusion problems, and 18 patients were re-explored for hematoma drainage (n=22/124, %17.3). The rate of hematoma and re-exploration was higher in patients who received anticoagulant and antiaggregant treatments synchronously (p=0.02). Three flaps were lost, and the overall success rate was 97.6%. Two patients died from perioperative complications. No major complications were observed at the donor site; minor complications were observed in 30 patients. CONCLUSION: The success rate for the 127 flaps in 124 patients were found comparable to those reported in the literature. These results show that successful outcomes can be achieved with experience and a head and neck team dedicated to improving the results in microsurgical reconstruction, and flap failure rarely occurs if perioperative care of the patients is given meticulously.

Supraclavicular artery island flap for head and neck reconstruction.

BACKGROUND: The ablative surgical resection has a critical importance for achieving better oncological outcomes for patients with head and neck cancer. However, radical surgical resections reveal the reconstruction requirement of complex anatomical structures. Microvascular free flaps have been recommended as a gold standard treatment choice for head and neck reconstruction following definitive oncological surgery. The supraclavicular artery island flap (SCAIF) is a thin and reliable fasciocutaneous pedicled flap that is simple and quick to harvest. MATERIAL AND METHODS: A total of 19 patients who underwent head and neck reconstruction with SCAIF were included in this study. The SCAIF was used for the reconstruction of oncological defects in 17 patients while it was used for the reconstruction of a skin defect on the lower face following radiotherapy in 1 patient and for cervical open wound (blast injury) closure in 1 patient. RESULTS: There were neither intraoperative nor postoperative major complications in any patient. The SCAIF has been used successfully in 18 of 19 patients for head and neck reconstructive surgery. Partial necrosis of the skin was detected in 1 patient (5.3%) only, while a total flap failure has not occurred in any patient. The partial skin necrosis was seen in an area of 1.5 cm of the distal end of the flap and was managed conservatively with local wound care. Wound dehiscence has not appeared in the flap donor area in any patient. CONCLUSION: The SCAIF constitutes a good alternative to free flaps, providing almost equivalent functional results and requiring less operative time and surgical effort.

Does Size Matter in Laryngology? Relation Between Body Height and Laryngeal Morphometry.

OBJECTIVE: Laryngeal framework surgery has been a topic of interest since last decades. To succeed with least morbidity, the most important step is mastering the anatomy of larynx. In this study, we aim to show the relation between body height and laryngeal morphometrics that are important during laryngeal framework surgeries. DATA SOURCES: Larynges of 187 fresh cadavers were dissected within 24 hours after death at the Council of Forensic Medicine. METHODS: Age, sex, weight, height, and a total of 12 measurements were taken from each cadaver. Results were subgrouped according to gender, age of 45, body height of 165 millimeters (mm), and thyroid cartilage height of 17 mm. These subgroups were compared for each measurement and ratio. RESULTS: A positive correlation was found between body height and thyroid cartilage height (hTC), thyroid cartilage width, vocal fold length, and distance from projection of anterior commissure (pAC) to inferior border of thyroid cartilage (TIB). Male gender, higher body heights, and higher thyroid cartilage heights significantly higher results were obtained. The ratio between pAC-TIB distance to hTC was found to be 0.54 in males and 0.52 in females, and this ratio was not statistically different in subgroups. CONCLUSION: Although all of the laryngeal measurements were found to be statistically significant in patients with higher body height, the ratio between pAC-TIB distance to hTC was independent. Thus, especially in patients with body heights longer than average, it should be safer to use the midpoint of the thyroid cartilage as a landmark for anterior commissure.

The Role of Indirect Laryngoscopy, Clinical and Ultrasonographic Assessment in Prediction of Difficult Airway.

OBJECTIVES: Pre-operative airway evaluation is essential to decrease the proportion of possible mortality and morbidity due to difficult airway (DA). The study aimed to evaluate the accuracy of pre-operative ultrasonographic airway assessment (UAA) and indirect laryngoscopy (IL) in predicting DA. STUDY DESIGN: Prospective obsevational study. METHODS: Preoperative clinical examination (body mass index [BMI], mallampati classification [MP], thyromental distance, sternomental distance, neck circumference), UAA (epiglottis-skin distance [ESD], hyoid bone-skin distance [HSD], the thickness of tongue root [ToTR], anterior commissure-skin distance [ACSD]) and IL with the rigid 70-degree laryngoscope were performed to predict DA (Cormack-Lehane grade 3 and 4). The sensitivity, specificity, positive predictive value (PP), and negative predictive values of the parameters were assessed. RESULTS: Twenty-two of 140 (15.7%) patients were diagnosed with DA. The cut-off points of ESD, HSD, ToTR, ACSD, and BMI were 2.09 cm, 0.835 cm, 4.05 cm, 0.545 cm, and 27.10, respectively. AUC values were 0.874, 0.885, 0.871, 0.658, and 0.751 in the same order. AUC values for IL and MP were 0.773 and 0.925, respectively. MP and HSD had the best sensitivity (91%), IL grading had the best specificity (100%), and PP (100%) value among all measurements. The best-balanced sensitivity (91%), specificity (97%), and PP (88%) values were obtained by combining the IL with MP and ESD or with MP and HSD. CONCLUSIONS: Ultrasonographic measurements and IL were found significantly correlated to predict DA. Combined parameters, the IL with MP and ESD or with MP and HSD, are the best parameters in predicting the DA. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E555-E560, 2021.

Our Experience with Supratracheal Partial Laryngectomy in Advanced Laryngeal Cancer: A Report of Five Cases.

Supratracheal laryngectomy (STL) is the ultimate option in conservation surgery, and can be used as an alternative to total laryngectomy in selected tumors. This case series is the first report from Turkey that analyzes the oncological and functional outcomes of STL along with a literature review. Files of five patients who underwent STL between June 2016 and June 2019 were analyzed. Primary tumor findings, postoperative pathology reports, treatment modalities and oncological and functional outcomes of the surgical intervention were noted. Two patients were operated on for horse-shoe glottic tumors with subglottic extension, one patient for primary subglottic mass and two for transglottic ventricular tumors with anterior subglottic extension. Pathological stage of two patients was T3, and of three patients was T4a due to thyroid cartilage invasion. No neck metastases were observed. Three patients with T4a primary tumor were treated with adjuvant radiotherapy. All patients were found disease free in their last follow-up visit. Nasogastric tube was removed in the 1st postoperative month in all patients. While one patient remained tracheostomized in the follow-up period, the remaining four were decannulated. This technique can be used as an alternative to total laryngectomy especially in selected cases with subglottic extension.

Squamous cell carcinoma development in Fanconi anemia patients who underwent hematopoietic stem cell transplantation.

We examined SCC development of 24 FA patients, who received HSCT from HLA-matched relatives. In our BMT center, we applied low-dose CY + LFI + ATG (n:13) as conditioning regimen for FA patients between 1992 and 1999, and CY + BU + ATG (n:11) between 1999 and 2002. The aim of this study was to investigate SCC development after HSCT and examine features of the follow-up patients. The 10-year overall survival (OS) of the group with LFI + regimen was 43%, whereas the group without LFI regimen was 60%. There was a statistically significant relationship between infections (viral/bacterial) and overall survival (Fisher's Exact test P < .001). Five out of 13 long-term (>1 year) surviving patients developed SCC in the HNSCC (n:4) and esophagus (n:2) region (a patient with oral SCC developed a second primary esophageal SCC). The SCC rate in our FA patients was 38%, four of the SCC patients were transplanted with irradiation used conditioning regimens, three of them had acuteGvHD (Grade II-III), only one developed chronic GvHD. The interval between HSCT and SCC diagnosis was median 13 (range 6-18) years, the age for the development of cancer was median 21 (range 15-32) years. Survival after SCC was low, median 6 months (range 6-12), due to delayed SCC diagnosis, tumor progression under therapy and treatment-related toxicities of the usually reduced RT and/or CT.

Malignant Transformation of Parotid Gland Non-sebaceous Lymphadenoma: Case Report and Review of Literature.

Non-sebaceous lymphadenoma is a sporadic benign tumor of salivary glands. Histopathologic and immunohistochemical properties, diagnostic criteria, and theories for the histologic origin of the disease have been defined and well-discussed in the literature. However, none of the cases showed malignant transformation to date. We reported a case of 54 years old female patient with a right preauricular mass. Magnetic resonance imaging demonstrated a 2 cm, well-defined contrast-enhanced mass in the right parotid gland. Fine needle aspiration cytology was undiagnostic but suspicious for malignancy. Total parotidectomy with facial nerve preservation was done. In the histopathological examination, non-sebaceous lymphadenoma regions and malignant cells with abundant cytoplasm, large vesicular nuclei, and prominent nucleoli, which occupied approximately 70% of the mass, were seen. The diagnosis was undifferentiated carcinoma arisen from non-sebaceous lymphadenoma. Adjuvant radiotherapy was given. No recurrence was detected during ten months of follow-up. This case is the first case of a malignancy developed from non-sebaceous lymphadenoma.

A Rare and Subtle Etiology of Chronic Oropharyngeal Pain: Isolated Internal Carotid Artery Kinking without Stenosis.

Carotid artery kinking is a frequent finding in duplex ultrasonography. However, isolated morphological changes without significant carotid stenosis are rarely symptomatic. Neck pain is a rare symptom in patients with carotid artery kinks. The vascular etiology in patients with persistent neck pain is usually overlooked. A 58-year-old female patient with chronic neck pain presented to our clinic. Following multidisciplinary team review, the symptoms were found due to the kinking of the internal carotid artery. In this report, we present the clinical presentation of the patient with the kinking of the internal carotid artery without stenosis, surgical management of the pathology, and a brief literature review.

Readibility, Understandability, and Quality of Online Education Materials for Vocal Fold Nodules.

OBJECTIVE: Vocal fold nodules are benign vocal fold lesions that can adversely affect quality of life. Differential diagnosis and treatment modalities of this disease are variable and patients often tend to use online materials to learn the insights. Access to knowledge via Internet is very easy; however, it is important to choose wisely because false and biased information might lead the patient to an inappropriate decision. In this study, we have evaluated the quality, readability, and understandability of online materials for vocal fold nodules. METHODS: An Internet search was performed for "Vocal fold nodule," "vocal fold nodule treatment," and "voice therapy for vocal fold nodule" by using Google search engine. Readability of each website was evaluated by using www.readable.io. Understandability and actionability of pages were measured by using the Patient Education Materials Assessment Tool (PEMAT). In the end, DISCERN instrument was used to measure the quality of information presented. RESULTS: After exclusion, total of 26 web pages were evaluated during the study. Four web pages graded as A level, 5 as B level, 11 as C level, and 5 as D level for language use. Average grade level for all of the web pages is 11.14 ± 1.75. Overall understandability score was found 59.0+ 12.1 (26.7-77.1), and overall quality score was measured 34.95 + 6.58 (53.75-26.5). CONCLUSION: The quality, readability, and understandability of the written materials are very low and in order for patients to read and learn from the online sources, contents of the written materials should be revised.

Comparison of long-term functional results between standard supracricoid laryngectomy and modified technique with sternohyoid muscle.

INTRODUCTION: Laryngeal cancer is the most common cancer of the upper respiratory tract. The main methods of treatment included surgery (partial laryngectomy and total laryngectomy) and radiation therapy. Laryngeal dysfunction is seen after both treatment modalities. OBJECTIVE: The aim of the study is to compare postoperative functional results of the standard supracricoid partial laryngectomy technique and a modified supracricoid partial laryngectomy technique using the sternohyoid muscle. METHODS: In total, 29 male patients (average years 58.20±9.00 years; range 41-79 years) with laryngeal squamous cell carcinoma who underwent supra cricoid partial laryngectomy were included. The patients were divided into two groups in terms of the surgical techniques. In Group A, all patients underwent standard supracricoid partial laryngectomy technique between January 2007 and November 2011. In Group B, all patients underwent modified supracricoid partial laryngectomy between August 2010 and November 2011. Fiberoptic endoscopic evaluation of swallowing test, short version of the voice handicap index scores, and the MD Anderson dysphagia inventory, the time of oral feeding and the decanulation of the patients after surgery of each groups were compared. RESULTS: The mean maximum phonation time was 8.68±4.21s in Group A and 15.24±6.16s in Group B (p>0.05). The S/Z (s/s) ratio was 1.23±0.35 in Group A and 1.08±0.26 in Group B (p>0.05); the voice handicap index averages were 9.86±4.77 in Group A and 12.42±12.54 in Group B (p>0.05); the fiberoptic endoscopic evaluation of swallowing test averages were calculated as 12.73±3.08 in Group A and 13.64±1.49 in Group B (p>0.05). In the MD Anderson dysphagia inventory, evaluation of swallowing, the emotional, physical, and functional scores were 29.21±4.11, 32.21±6.85, and 20.14±2.17 in the Group B, and 29.20±2.54, 32.4±4.79, and 19±1.92 in Group A, respectively. CONCLUSION: Although there is no statistical difference in functional outcome comparisons, if rules are adhered to in preoperative patient selection, modified supracricoid partial laryngectomy can be applied safely and meaningful gains can be achieved in functional outcomes.

Intraosseous Mucoepidermoid Carcinoma of the Jaw: Report of Three Cases.

Mucoepidermoid carcinoma (MEC) is the most common malignant tumor of the salivary glands and is seen most commonly in the parotid gland. Intraosseous MECs can be rarely seen and is mostly detected in the posterior part of the mandible. This condition can be acknowledged as an entity different from salivary gland MECs. In this case series, we delineated three patients of intraosseous MEC, two mandible tumors and one maxillary tumor and discussed the diagnostic characteristics and treatment methods of this rare entity.

68Ga-DOTATATE PET-CT imaging in carotid body paragangliomas.

OBJECTIVE: The aim of this study was to present our experience in the baseline evaluation of carotid body paragangliomas (CBP) with 68Ga-DOTATATE PET-CT. METHODS: Five patients (4F, 1M; age 24-73 years) with CBPs who underwent 68Ga-DOTATATE PET-CT scan before the treatment were evaluated retrospectively. PET-CT images were analyzed visually as well as semiquantitatively, with measurement of maximum standardized uptake value (SUVmax). RESULTS: All patients had unilateral CBP lesion, showed intense 68Ga-DOTATATE uptake in PET-CT. Additionally, 68Ga-DOTATATE avid lesions were found in two patients. One of them had focal intense uptake in thyroid gland and frontal cerebrum. The other one had intense uptake in bone and adrenal mass. Four patients were operated for unilateral primary CBP. Last patient was treated with peptide receptor radionuclide therapy (177Lu-DOTATATE) for both metastatic pheochromocytoma and CBP. CONCLUSIONS: 68Ga-DOTATATE PET-CT is a valuable imaging modality for staging of CBPs, detecting unknown lesions and changing the management of patients. It is also useful in demonstrating expression of SSTRs for PRRT opportunity.

High frequency jet ventilation during endolaryngeal surgery: Risk factors for complications.

Objective: Microlaryngeal surgery requires teamwork between surgeons and anesthesiologists. High-frequency jet ventilation (HFJV) is an artificial breathing technique, preferred during endolaryngeal interventions, which offers a good solution for the requirements. Most studies investigating independent risk factors for intraoperative complications during HFJV in endolaryngeal surgery (ELS) has been retrospective and not standardized and the anesthetic approach has not been standardized. This prospective cohort study aimed to identify risk factors of complications related to HFJV in ELS under a standardized anesthesia regimen. Methods: 243 patients who underwent ELS with infraglottic HFJV were investigated. Infraglottic jet ventilation catheter was placed and anesthesia was standardized. Demographic and operative data were noted. Hemodynamics, SpO2 and end-tidal CO2 were recorded at regular intervals. Complications such as hemodynamic disturbances, respiratory problems, barotrauma, equipment failure and requirement for conventional ventilation were also documented. Results: 222 patients were included. Hypoxia, hypercapnia and the need for intubation were observed in 20(9%), 4(1.8%), 10(4.5%) patients. Bradycardia, hypotension and arrhythmia were observed in six (2.7%), 24(10.8%), and four (1.8%) patients respectively. Respiratory complications were associated with body mass index (BMI) (p < 0.001, OR: 1.57, 95%CI: 1.31­1.88) and previous major airway surgery (p < 0.001, OR: 34.0, 95%CI:3.52­328.24), whereas hemodynamic complications were associated with duration of the operation (p = 0.034, OR:1.04, 95%CI:1.0­1.09) and history of previous major airway surgery (p = 0.005, OR:9.57, 95%CI:1.97­46.49). Conclusion: Infraglottic HFJV can be evaluated as an alternative breathing technique to conventional ventilation during endolaryngeal interventions. However, longer operation and previous laryngeal surgeries can increase the incidence of respiratory complications.

Comprehensive analysis of parotid mass: A retrospective study of 369 cases.

OBJECTIVE: To present the results of patients who underwent superficial or total parotidectomy because of parotid gland tumors in our tertiary care clinic. METHODS: The data of 362 patients who underwent parotid surgery from January 2008 to November 2015 were collected and analyzed in demographic, histopathological features, and complications. RESULTS: Three hundred sixty-nine cases (performed in 359 patients) were analyzed and we assessed complications of parotid surgery such as transient or permanent facial paralysis and Frey's syndrome. Pleomorphic adenomas and Warthin's tumors consisted 74% of all parotid gland tumors. These tumors were generally located in the superficial lobe and tail of the parotid gland (81%). Also, tumor size in the positive surgical margin group was larger than in the negative surgical margin group (p=0.012). CONCLUSIONS: Most of parotid gland tumors are benign. However, the frequency of malignancy increases in deep lobe of parotid gland. High grade malignant tumors have more tendency to have positive surgical margin during surgery, and facial paresis preoperatively.

Endonasal endoscopic nasopharyngectomy for the treatment of nasopharyngeal papillary adenocarcinoma: Report of a rare case.

We report a case of low-grade nasopharyngeal papillary adenocarcinoma in a 9 year-old male that was diagnosed incidentally after an adenoidectomy procedure and treated with endonasal endoscopic nasopharyngectomy without any adjuvant therapy. The patient has been followed up for 3 years with no evidence of recurrence. We point out the importance of preoperative fiberoptic nasopharyngoscopy in the absence of longstanding symptoms in school-aged children and histopathologic examination of adenoidectomy specimens in the presence of atypical findings. We also suggest endonasal endoscopic resection in case of papillary adenocarcinoma.

Displacement of a Broken Dental Injection Needle Into the Perivertebral Space.

Dental injection needle breakage is an uncommon problem in dental practice. Displacement of the broken fragment into anatomical spaces is, on the other hand, a serious complication that occurs most commonly during inferior alveolar nerve blocks as a result of material wear, incorrect application of the anesthesia technique, or sudden movement of the patient during injection. Further complications such as infection, trismus, and nerve paralysis may exacerbate the condition and, if not treated adequately, life-threatening conditions may develop over time as the fragment dislodges deeper in soft tissues. Clinical symptoms of the patient, as well as the findings gathered from detailed physical examination and radiographic evaluation, are important factors to consider before performing an exploratory surgery. Removal of a broken needle may be troublesome due to its proximity to vital anatomic structures. Multislice computed tomography is a reliable imaging modality that provides accurate information to pinpoint the exact location of the needle fragment.This report describes a case of needle breakage occurred during inferior alveolar nerve block which was performed to extract a third molar tooth and the migration of the broken fragment from the right mandibular ramus area into the perivertebral space, with special emphasis on the surgical retrieval technique with multiplanar computed tomography imaging guidance.