Three-Dimensional Assessment of Frontal Bossing and Temporal Pinching in Patients with Sagittal Craniosynostosis Using Curvature Analysis

BACKGROUND

Sagittal craniosynostosis results in varying degrees of frontal bossing and bilateral temporal pinching. This study assessed the three-dimensional changes in these regions using curvature analysis and volumetric analysis before and 1 year after extended sagittal strip craniectomy (ESC) with postoperative helmet therapy.

METHODS

A retrospective review of three-dimensional photographs of 50 subjects treated with ESC with postoperative helmet therapy and 50 age-matched controls was performed. Images were collected preoperatively and 1 year postoperatively. Forehead convexity and temple concavity were quantified. Computed tomographic scans of subjects with and without sagittal synostosis were analyzed to assess the percentage of total intracranial volume (ICV) in the anterior cranial fossa before and after ESC with postoperative helmet therapy.

RESULTS

Forehead convexity in the ESC with postoperative helmet therapy group preoperatively (24.49 ± 3.16 m -1 ) was significantly greater than controls (22.48 ± 3.84 m -1 ; P = 0.005). Forehead convexity significantly decreased after ESC with postoperative helmet therapy (18.79 ± 2.43 m -1 ; P < 0.001) and did not differ from controls (19.67 ± 3.08 m -1 ; P = 0.115). The ESC group had more concave temples preoperatively (-10.27 ± 4.37 m -1 ) as compared with controls (-6.99 ± 3.55 m -1 ; P < 0.001). Temple concavity significantly decreased after ESC (-4.82 ± 3.17 m -1 ; P < 0.001) and did not differ from controls (-5.64 ± 3.27 m -1 ; P = 0.075). In the ESC group, the percentage ICV in the anterior cranial fossa decreased from 22.03% to 18.99% after surgery, whereas the anterior volume in controls was stable (17.74% to 16.81%).

CONCLUSIONS

The ESC group had significantly greater forehead convexity, temple concavity and anterior cranial fossa volume compared with controls. One year after ESC with postoperative helmet therapy, forehead convexity, temple concavity, and percentage ICV in the anterior fossa were comparable to controls.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Multicenter comparison of head shape outcomes for three minimally invasive strip craniectomy techniques for sagittal craniosynostosis

OBJECTIVE

A literature gap exists comparing whole head shape outcome following correction of sagittal craniosynostosis. The objective of this multicenter study was to provide an analysis of long-term results following three different endoscopic strip craniectomy techniques for correction of sagittal craniosynostosis: 1) spring-assisted strip craniectomy, 2) wide-strip craniectomy with biparietal and bitemporal barrel-stave wedge osteotomies plus helmet orthosis, and 3) narrow-strip craniectomy plus orthosis without barrel staves.

METHODS

Pre- and postoperative 3D stereophotogrammetric images were collected from patients who underwent craniosynostosis surgery. Procedures were divided among institutions as follows: spring-assisted strip craniectomies were performed at Atrium Health Wake Forest Baptist Hospital; narrow-strip craniectomies were performed at St. Louis Children's Hospital by one craniofacial surgeon; and wide-vertex craniectomies were performed at St. Louis Children's Hospital prior to 2010, and then continued at Children's Medical Center Dallas. Pre- and postoperative 3D whole-head composite images were generated for each procedure to visually represent outcomes at final follow-up and compared with age-matched normal controls.

RESULTS

Patients in the spring-assisted strip craniectomy group showed normalization of frontal bossing and skull height compared with age-matched controls, whereas patients undergoing wide-strip craniectomy showed greater correction of occipital protrusion. Patients in the narrow-strip craniectomy cohort had intermediate results between these outcomes. Nested aggregate head shapes showed good correction of head shapes from all techniques.

CONCLUSIONS

This large, retrospective, multicenter study illustrated whole head shape outcomes from three different craniectomy procedures. Although each procedure showed some differences in loci of primary correction, all three surgical methods demonstrated good correction of primary scaphocephalic deformity.

Three-dimensional Analysis of Facial Asymmetry in Unilateral Lambdoid Craniosynostosis

OBJECTIVE

Unilateral lambdoid synostosis (ULS) is characterized by occipital flattening, mastoid bulging, and contralateral parietal bossing. Anterior craniofacial features are less well-defined. This study utilizes volumetric, craniometric, and composite heat maps of three-dimensional (3D) rendered CT scans to analyze anterior craniofacial asymmetry in ULS and compared to controls.

DESIGN

A retrospective review of three-dimensional CT scans.

SETTING

Tertiary care pediatric institution.

PATIENTS, PARTICIPANTS

30 ULS and 30 control patients.

MAIN OUTCOME MEASURE(S)

Volumetric and craniometric analysis of the anterior fossa, orbits, zygomas, maxilla, and mandible was performed.

RESULTS

The anterior fossa volume was greater bilaterally (0.047, 0.038), and the fossa angle was more anterior contralaterally (<0.001) and more anterior bilaterally than controls (0.038, 0.033). The orbits had greater height and lesser depth bilaterally compared to controls (0.006, 0.009; < 0.001, < 0.001). Zygoma length was significantly greater on the contralateral side than controls (0.048; < 0.001). Nasal contralateral deviation of 3.57  ±  1.97°. The maxillary length was longer on the contralateral side (0.045). The mandibular angle was more anterior on the ipsilateral side and posterior on the contralateral side (<0.001) compared to controls (0.042, < 0.001). Chin had a contralateral deviation of 1.04  ±  3.74°.

CONCLUSIONS

ULS has significant asymmetry in the anterior craniofacial skeleton. There is a bilateral expansion of the anterior cranial fossa with greater frontal bossing on the contralateral side. Increased orbital height and decreased depth. Contralateral zygomatic and mandibular body lengthening with posterior mandibular deviation. These features may provide more effective diagnosis and potential clinical management strategies.

Alar Asymmetry in Patients with Unilateral Cleft Lip: Implications for Secondary Rhinoplasty

OBJECTIVE

Alar asymmetry in unilateral cleft lip (UCL) nasal deformity is a well-recognized clinical feature. However, there is a lack of comprehensive quantitative analysis of this asymmetry. This study compares the shape, volume, and axis rotation between the cleft and non-cleft ala in skeletally mature patients with UCL.

DESIGN

A retrospective comparative study utilizing three-dimensional rendered CT scans.

SETTING

Tertiary care pediatric institution.

PATIENTS, PARTICIPANTS

This study included 18 patients with UCL nasal deformity at skeletal maturity.

MAIN OUTCOME MEASURE(S)

Cleft and non-cleft side ala volume, surface area, and axis to the midsagittal plane.

RESULTS

The cleft-side ala was significantly lesser in volume by 27.3%, significantly lesser in surface area by 17.6%, and significantly greater in surface area to volume ratio by 14.6% than the non-cleft ala. The cleft-side ala was significantly greater by 43.1% horizontal axis to the midsagittal plane. In patients with primary rhinoplasty, the cleft-side ala had 28.0% less volume and 18.7% less surface area. In intermediate rhinoplasty, the cleft-side ala had 39.1% less volume and 23.5% less surface area than the non-cleft ala.

CONCLUSIONS

Significant asymmetry exists between the cleft-side and non-cleft ala in patients with UCL. The cleft-side ala is significantly smaller in volume and surface area than the non-cleft ala. Additionally, the cleft-side ala demonstrates a significantly greater horizontal axis that contributes considerably to nasal asymmetry, supporting the need to restore a normal vertical axis to the clef-side ala.

Three-dimensional Anthropometric Analysis of Racial and Ethnic Differences in Unilateral and Bilateral Cleft Nasal Deformity

This study used three-dimensional measurements to provide a nasolabial analysis of patients with unilateral cleft lip and palate (UCLP), bilateral cleft lip and palate (BCLP), and controls across different races and ethnicities.

A retrospective comparative study.

Tertiary care pediatric institution.

The study included 90 patients with UCLP, 43 patients with BCLP, and 90 matched controls. Patients are separated as self-identified Caucasian, Hispanic, or African American.

Nasal length, nasal protrusion, columellar height, columellar width, tip width, alar width, alar base width, nasolabial angle, upper lip length, philtrum length, nostril height, and nostril width.

All UCLP groups had significantly greater columella and tip widths and decreased nasolabial angles than controls. All BCLP groups had significantly greater columella width, tip width, nasolabial angle, and nostril widths. Upper lip length, philtrum length, and nostril height were significantly decreased in BCLP compared to controls. Across UCLP groups, African Americans had significantly decreased nasal protrusion and columella height and a significantly increased columella width compared to Caucasians and Hispanics. Alar and alar base widths were significantly different between all groups. Across BCLP groups, the Caucasian nostril width was significantly less than the African Americans.

These findings suggest that when correcting nasolabial characteristics in patients with cleft lip, it is important to consider racial and ethnic differences to achieve a normal appearance. Specifically, goals for alar width, alar base width, nasal tip, and projection should be tailored to the patient's race and ethnicity.

3D imaging of vascular anomalies using raster-scanning optoacoustic mesoscopy

OBJECTIVES

Vascular anomalies such as capillary malformations (CMs) and infantile hemangiomas (IHs) are common pediatric vascular disorders that are treated with therapeutic laser. The treatment method, however, relies on subjective evaluation of clinical findings and can have unpredictable results. Raster-scanning optoacoustic mesoscopy (RSOM) is an innovative imaging technology using pulsed-light laser to excite hemoglobin, generating ultrasound waves that are converted into three-dimensional images of tissues. RSOM can provide objective information about superficial structures such as the microvasculature of vascular anomalies.

MATERIALS AND METHODS

In this study, we explore the clinical potential of RSOM to study vascular anomalies before and after laser treatment. We scanned nine patients with CM (n = 6) and IH (n = 3) who underwent laser treatment and calculated the blood vessel volume.

RESULTS

Overall, there was a posttreatment volume increase in CM, and a decrease in IH.

CONCLUSION

These findings support the possibility that RSOM may have a role in developing an objective method of evaluating these lesions, leading to a tailored treatment approach and avoidance of adverse outcomes.

Craniofacial Growth and Asymmetry in Newborns: A Longitudinal 3D Assessment

OBJECTIVE

To evaluate the development of the craniofacial region in healthy infants and analyze the asymmetry pattern in the first year of life.

METHODS

The participants were grouped by sex and age (1, 2, 4, 6, 9, and 12 months) to receive three-dimensional (3D) photographs. Stereoscopic craniofacial photos were captured and transformed into a series of craniofacial meshes in each group. The growth patterns of the anthropometric indices and the degree of craniofacial asymmetry were measured, and average craniofacial meshes and color-asymmetry maps with craniofacial asymmetry scores were calculated.

RESULTS

A total of 373 photographs from 66 infants were obtained. In both genders, the highest and lowest growth rates for all anthropometric indices were noted between 1 and 2 months and between 9 and 12 months, respectively. Overall, male infants had higher anthropometric indices, head volume, and head circumference than female infants. The craniofacial asymmetry score was presented with a descending pattern from 1 to 12 months of age in both sex groups. Both sex groups showed decreased left-sided laterality in the temporal-parietal-occipital region between 1 and 4 months of age and increased right frontal-temporal prominence between 6 and 12 months of age.

CONCLUSIONS

A longitudinal evaluation of the craniofacial growth of healthy infants during their first year of life was presented.

Open Versus Minimally Invasive Approach for Craniosynostosis: Analysis of the National Surgical Quality Improvement Program-Pediatric

OBJECTIVE

This multicenter study aimed to compare demographic, operative, and short-term outcomes data between open and minimally invasive surgical approaches for craniosynostosis repair utilizing the American College of Surgeon's National Surgical Quality Improvement Program Pediatric (NSQIP-P) database and highlight surgical disparities among races and ethnicities.

DESIGN

Retrospective review of large multicenter database.

SETTING

Freestanding general acute care children's hospitals, children's hospitals within a larger hospital, specialty children's hospitals, or general acute care hospitals with a pediatric wing.

PATIENTS AND PARTICIPANTS

A total of 4931 pediatric patients underwent craniosynostosis correction within the NSQIP-P database from 2013 to 2019.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

Demographic information included age at surgery, sex, race, and ethnicity. Operative and outcomes measures included operative time, anesthesia time, days until discharge, postoperative complications, blood transfusions, 30-day readmission, and 30-day unplanned return to operating room.

RESULTS

Patients who underwent minimally invasive surgery had significantly shorter operative and anesthesia times (p < .001; p < .001), fewer days until discharge (p < .001), fewer postoperative complications (p < .05), and less blood transfusions (p < .001). The proportion of White patients was significantly higher in the minimally invasive surgery group (p < .01), whereas Black and Hispanic patients had a significantly higher proportion in the open surgery group (p < .001; p < .001). Additionally, the percentage of patients undergoing minimally invasive surgery increased from 3.8% in 2014 to over 13% in 2019.

CONCLUSIONS

This study adds to a growing consensus that minimally invasive surgery has significantly decreased operative time, anesthesia time, transfusion rates, length of hospital stay, and postoperative complications compared to open surgery. Racial and ethnic surgical disparities showed larger proportions of Black and Hispanic populations undergoing open procedures.

Longitudinal composite 3D faces and facial growth trends in children 6-11 years of age using 3D cephalometric surface imaging

BACKGROUND

Normative craniofacial anthropometry provides clinically important reference values used in the treatment of craniofacial conditions. Few objective datasets of normative data exist for children.

AIM

To establish normative data regarding craniofacial morphology changes with growth in children.

SUBJECTS AND METHODS

3D surface images of the same group of healthy children aged 6 - 11 years old recruited from a Dallas school were taken annually between the years 2015 - 2020. Composite 3D cephalometric faces were created for boys and girls of each age. General and craniofacial anthropometric measurements were compared.

RESULTS

Seven hundred ninety one individual stereophotogrammetric acquisitions were used (400 boys, 391 girls) taken from 180 children. Linear facial, orbital, nasal, and oral anthropometric measurements revealed a consistent increase in magnitude with age. Composite 3D face comparisons revealed prominent vertical and anteroposterior growth trends in the lower and upper facial regions.

CONCLUSION

This study presents a longitudinal 3D control dataset of the same group of children over a 6-year period that can serve as reference norms for facial growth values and trends in children aged 6-11 years. The composite 3D normative faces are available for clinical and research purposes upon request, which may be interrogated and measured according to user need and preference.

Analysis of Facial Movement in Repaired Unilateral Cleft Lip Using Three-Dimensional Motion Capture

ABSTRACT

Unilateral cleft lip (UCL) is one of the most common craniofacial deformities. Surgical intervention reconstructs lip and nose anatomy; however, some degree of asymmetry persists after repair. This demonstrates a need for a model for studying and improving outcomes for patients with orofacial clefts. This study's main question was whether there is a significant difference in dynamic facial asymmetry between participants with repaired UCLs and control participants during smiling. Ten pediatric subjects with repaired left UCLs and 12 with no craniofacial diagnoses were recorded performing maximum smiles using a markerless 4D video stereophotogrammetrical system. A facial mesh template containing 884 landmarks was conformed to each initial frame and tracked throughout. Kinetic analysis of smiles was performed by calculating landmark 3D Euclidean distance between frames. Patients with left repaired UCL showed increasing facial asymmetry throughout smiling. Oral commissures, upper, and lower lips demonstrated significantly greater movement on the right side (P < 0.05). Control patients showed facial asymmetry during the first half of smiling, with greater movement on the left side. Displacement difference between right and left was significantly greater at oral commissures and upper lips in patients with repaired ULC compared to control patients. This study provides a highly detailed, quantitative analysis of postoperative UCLs, and help improve outcomes of future repair surgeries.

Assessing outcomes of ear molding therapy by health care providers and convolutional neural network

Ear molding therapy is a nonsurgical technique to correct certain congenital auricular deformities. While the advantages of nonsurgical treatments over otoplasty are well-described, few studies have assessed aesthetic outcomes. In this study, we compared assessments of outcomes of ear molding therapy for 283 ears by experienced healthcare providers and a previously developed deep learning CNN model. 2D photographs of ears were obtained as a standard of care in our onsite photography studio. Physician assistants (PAs) rated the photographs using a 5-point Likert scale ranging from 1(poor) to 5(excellent) and the CNN assessment was categorical, classifying each photo as either “normal” or “deformed”. On average, the PAs classified 75.6% of photographs as good to excellent outcomes (scores 4 and 5). Similarly, the CNN classified 75.3% of the photographs as normal. The inter-rater agreement between the PAs ranged between 72 and 81%, while there was a 69.6% agreement between the machine model and the inter-rater majority agreement between at least two PAs (i.e., when at least two PAs gave a simultaneous score < 4 or ≥ 4). This study shows that noninvasive ear molding therapy has excellent outcomes in general. In addition, it indicates that with further training and validation, machine learning techniques, like CNN, have the capability to accurately mimic provider assessment while removing the subjectivity of human evaluation making it a robust tool for ear deformity identification and outcome evaluation.

Anterior "W" Tongue Reduction for Macroglossia in Beckwith-Wiedemann Syndrome

INTRODUCTION

Macroglossia occurs in 80% to 99% of patients with Beckwith-Wiedemann syndrome (BWS) and a variety of surgical techniques for tongue reduction are offered by surgeons. The purpose of this study is to evaluate the postoperative outcomes of the anterior "W" tongue reduction technique in patients with BWS.

METHODS

A retrospective review was conducted of all patients diagnosed with BWS that underwent an anterior "W" tongue reduction for macroglossia in the past 7 years, performed by 2 surgeons. Demographics, procedural characteristics, perioperative outcomes, and complications were assessed.

RESULTS

A total of 19 patients met inclusion criteria consisting of 8 male and 11 female patients. The mean age at the time of surgery was 405 days, mean surgeon operating time was 1.06 h, and mean length of follow-up was 467 days. Postoperative oral competence was observed in 100% of patients. There was no reported history of sleep apnea or airway compromise. Speech delay was seen in 4 patients pre- and postoperatively. Feeding issues decreased from 7 patients preoperatively to 1 patient postoperatively. Preoperative prevalence of class III malocclusion (53%) and isolated anterior open bite (26%) decreased postoperatively to 37% and 16%, respectively. The only reported complications were superficial tip wound dehiscence in 3 patients treated with nystatin antifungal therapy. None of the patients required revisional surgery.

CONCLUSION

Patients treated with the anterior "W" tongue reduction technique had low rates of perioperative complications and significant improvements in oral competence. Anterior "W" tongue reduction is safe and effective for the correction of macroglossia in patients with BWS.

Comparison of Head Shape Outcomes in Metopic Synostosis Using Limited Strip Craniectomy and Open Vault Reconstruction Techniques

AIM

Metopic craniosynostosis (MCS), with its trigonocephalic head shape, is often treated with either limited incision strip craniectomy (LISC) followed by helmet orthotic treatment, or open cranial vault reconstruction techniques (OCVR). There is controversy regarding resultant shape outcomes among craniofacial surgeons. Those adverse to LISC claim normal head shape is never attained, while proponents believe there is gradual correction to an equivalent outcome. This study aims to quantitate, over time, the three-dimensional (3D) head shapes in patients who have undergone LISC or OCVR intervention for MCS.

METHODS

Sixty-three 3D images of 26 patients with MCS were analyzed retrospectively. Head shape analyses were performed at: (1) preoperative, (2) 1-month postoperative, (3) 10 to 14 months postoperative (1 year), and (4) 2 years postoperative. Composite 3D head shapes of patients were compared at each time point. Two-dimensional (2D) standardized cross sections of the forehead were also compared.

RESULTS

Composite head shapes for both groups were nested, to allow visual comparison as the child's forehead grows and expands. The difference between LISC and OCVR 2D cross sections was calculated; 108.26 mm preoperatively, 127.18 mm after 1-month postoperative, 51.05 mm after 10 to 14 months postoperative, and 27.03 mm after 2 years postoperative.

CONCLUSIONS

This study found excellent head shape outcomes for both the LISC and OCVR techniques at 2 years of age. It also corroborates the slow and progressive improvement in head shape with the LISC technique. This study highlights the advantages of 3D photography for measurement of contour outcomes, utilizing both 2D vector and 3D whole head analytical techniques.

Three-Dimensional Analysis of Bilateral Cleft Lip and Palate Nasal Deformity

OBJECTIVE

This cross-sectional study utilizes 3-dimensional analysis to assess nasal morphology in patients with bilateral cleft lip and palate (BCLP) compared to controls across the timeline of cleft care.

DESIGN

Retrospective comparative cross-sectional study.

SETTING

Tertiary pediatric academic institution.

PATIENTS AND PARTICIPANTS

One hundred and twelve patients with BCLP and an equal number of age and sex-matched control participants.

MAIN OUTCOME MEASURE(S)

Nasolabial angle, nasal length, nasal protrusion, columella length, columella width, nasal tip width, alar width, and alar base width were collected at each time point. The measurements were collected pre-nasoalveolar molding (NAM) therapy, post-NAM therapy, post-primary cleft rhinoplasty, 1 year, 5 years, 10 years, and 15 years of age.

RESULTS

Nasolabial angle and nasal tip width were significantly different from controls from pre-NAM through 15 years of age time points. Nasal length was not significantly different at any time point. Alar width and alar base width were significantly different from pre-NAM through 10 years of age time points. Nasal protrusion, columella length, and columella width were significantly different from pre-NAM through 5 years of age time points.

CONCLUSIONS

This study demonstrates that three-dimensional photogrammetry is effective in assessing the changes in nasal morphology that occur throughout the course of care in patients with BCLP from before cleft lip repair to the completion of nasal growth.

The Use of Eye Tracking to Discern the Threshold at Which Metopic Orbitofrontal Deformity Attracts Attention

INTRODUCTION AND OBJECTIVES

Surgical treatment for trigonocephaly aims to eliminate a stigmatizing deformity, yet the severity that captures unwanted attention is unknown. Surgeons intervene at different points of severity, eliciting controversy. This study used eye tracking to investigate when deformity is perceived.

MATERIAL AND METHODS

Three-dimensional photogrammetric images of a normal child and a child with trigonocephaly were mathematically deformed, in 10% increments, to create a spectrum of 11 images. These images were shown to participants using an eye tracker. Participants' gaze patterns were analyzed, and participants were asked if each image looked "normal" or "abnormal."

RESULTS

Sixty-six graduate students were recruited. Average dwell time toward pathologic areas of interest (AOIs) increased proportionally, from 0.77 ± 0.33 seconds at 0% deformity to 1.08 ± 0.75 seconds at 100% deformity (P < .0001). A majority of participants did not agree an image looked "abnormal" until 90% deformity from any angle.

CONCLUSION

Eye tracking can be used as a proxy for attention threshold toward orbitofrontal deformity. The amount of attention toward orbitofrontal AOIs increased proportionally with severity. Participants did not generally agree there was "abnormality" until deformity was severe. This study supports the assertion that surgical intervention may be best reserved for more severe deformity.

Identifying Ear Abnormality from 2D Photographs Using Convolutional Neural Networks

Quantifying ear deformity using linear measurements and mathematical modeling is difficult due to the ear's complex shape. Machine learning techniques, such as convolutional neural networks (CNNs), are well-suited for this role. CNNs are deep learning methods capable of finding complex patterns from medical images, automatically building solution models capable of machine diagnosis. In this study, we applied CNN to automatically identify ear deformity from 2D photographs. Institutional review board (IRB) approval was obtained for this retrospective study to train and test the CNNs. Photographs of patients with and without ear deformity were obtained as standard of care in our photography studio. Profile photographs were obtained for one or both ears. A total of 671 profile pictures were used in this study including: 457 photographs of patients with ear deformity and 214 photographs of patients with normal ears. Photographs were cropped to the ear boundary and randomly divided into training (60%), validation (20%), and testing (20%) datasets. We modified the softmax classifier in the last layer in GoogLeNet, a deep CNN, to generate an ear deformity detection model in Matlab. All images were deemed of high quality and usable for training and testing. It took about 2 hours to train the system and the training accuracy reached almost 100%. The test accuracy was about 94.1%. We demonstrate that deep learning has a great potential in identifying ear deformity. These machine learning techniques hold the promise in being used in the future to evaluate treatment outcomes.

Kinematic Analysis of Smiles in the Healthy Pediatric Population Using 3-Dimensional Motion Capture

Introduction:

Facial normalcy, as measured with 2-dimensional or 3-dimensional photographs, has been documented in the healthy pediatric population. However, static images convey far from a complete representation of an individual’s daily interactions with peers. Craniofacial surgery induces changes to soft or osseous tissues and thereby affects dynamic facial expression. To-date, there has not been rigorous, dynamic quantification of normal facial expression. In this study, we used 4-dimensional (4D) imaging to assess the facial expression of healthy children to provide a normative reference point for craniofacial surgeons.

Methods:

A total of 36 healthy pediatric volunteers underwent 4D video recordings while performing a maximal voluntary smile. A face template containing 884 landmarks was registered and tracked throughout the videos using Dimensional Imaging software. Participants were divided into 2 smile groups: open-lip smile and closed-lip smile. Kinematic analysis of smiles was calculated for every landmark from its position in the resting frame to its terminal displacement.

Results:

Composite smiles and Euclidean distance maps were generated displaying areas of greatest displacement near the oral commissures. There was significant difference between closed-lip and open-lip groups in regions of eyes and cheeks. In addition, the open-lip smile group demonstrated significantly greater displacement in the oral commissure on the left side compared to the right ( P < .05); whereas, in the closed-lip group, the eyes and cheeks moved significantly more on the right side.

Conclusion:

This study presents an innovative method that can be used to evaluate facial expressions to help craniofacial surgeons restore functional movement in patients with facial anomalies.

Comparative Volume Analysis of Alveolar Defects by 3D Simulation

A precise volumetric assessment of maxillary alveolar defects in patients with cleft lip and palate can reduce donor site morbidity or allow accurate preparation of bone substitutes in future applications. However, there is a lack of agreement regarding the optimal volumetric technique to adopt. This study measured the alveolar bone defects by using two cone-beam computed tomography (CBCT)-based surgical simulation methods. Presurgical CBCT scans from 32 patients with unilateral or bilateral clefts undergoing alveolar bone graft surgery were analyzed. Two hands-on CBCT-based volumetric measurement methods were compared: the 3D real-scale printed model-based surgical method and the virtual surgical method. Different densities of CBCT were compared. Intra- and inter-examiner reliability was assessed. For patients with unilateral clefts, the average alveolar defect volumes were 1.09 ± 0.24 and 1.09 ± 0.25 mL (p > 0.05) for 3D printing- and virtual-based models, respectively; for patients with bilateral clefts, they were 2.05 ± 0.22 and 2.02 ± 0.27 mL (p > 0.05), respectively. Bland–Altman analysis revealed that the methods were equivalent for unilateral and bilateral alveolar cleft defect assessment. No significant differences or linear relationships were observed between adjacent different densities of CBCT for model production to obtain the measured volumes. Intra- and inter-examiner reliability was moderate to good (intraclass correlation coefficient (ICC) > 0.6) for all measurements. This study revealed that the volume of unilateral and bilateral alveolar cleft defects can be equally quantified by 3D-printed and virtual surgical simulation methods and provides alveolar defect-specific volumes which can serve as a reference for planning and execution of alveolar bone graft surgery.

Examining correlations of oxygen sensitive MRI (BOLD/TOLD) with [18F]FMISO PET in rat prostate tumors

Hypoxia is regarded as a potential prognostic biomarker for tumor aggressiveness, progression, and response to therapy. The radiotracer ¹⁸F-fluoromisonidazole ([¹⁸F]FMISO) has been used with positron emission tomography (PET) to reveal tumor hypoxia. Meanwhile, blood oxygen level dependent (BOLD) MRI and tissue oxygen level dependent (TOLD) MRI offer insight into oxygenation based on endogenous signals without the need for radiolabels. Here, we compared BOLD and TOLD MRI with [¹⁸F]FMISO uptake using Dunning prostate R3327-AT1 tumor bearing rats. BOLD and TOLD MRI were acquired with respect to an oxygen gas breathing challenge. The following day, dynamic PET was performed up to 90 minutes following IV injection of [¹⁸F]FMISO. Tumors showed distinct heterogeneity based on each technique. Correlations were observed between magnitude of mean BOLD or TOLD MRI signal responses to oxygen-breathing challenge and initial distribution of [¹⁸F]FMISO. Correlations were observed for whole tumor as well on a regional basis with stronger correlations in the well perfused tumor periphery indicating the strong influence of perfused vasculature. After 90 minutes most correlations with signal intensity became quite weak, but correlations were observed between hypoxic fraction based on FMISO and fractions of tumor showing BOLD or TOLD response in a subset of tumors. This emphasizes the importance of considering regional heterogeneity and responsive fractions, as opposed to simple magnitudes of responses. Although the data represent a small cohort of tumors they present direct correlations between oxygen sensitive MRI and PET hypoxia reporter agents in the same tumors, indicating the potential utility of further investigations.

Improving the accuracy of automated cleft speech evaluation

An automated cleft speech evaluator, available globally, has the potential to dramatically improve quality of life for children born with a cleft palate, as well as eliminating bias for outcome collaboration between cleft centers in the developed world. Our automated cleft speech evaluator interprets resonance and articulatory cleft speech errors to distinguish between normal speech, velopharyngeal dysfunction and articulatory speech errors. This article describes a significant update in the efficiency of our evaluator. Speech samples from our Craniofacial Team clinic were recorded and rated independently by two experienced speech pathologists: 60 patients were used to train the evaluator, and the evaluator was tested on the 13 subsequent patients. All sounds from 6 of the CAPS-A-AM sentences were used to train the system. The inter-speech pathologist agreement rate was 79%. Our cleft speech evaluator achieved 85% agreement with the combined speech pathologist rating, compared with 65% agreement using the previous training model. This automated cleft speech evaluator demonstrates good accuracy despite low training numbers. We anticipate that as the training samples increase, the accuracy will match human listeners.

Comparison of an unsupervised machine learning algorithm and surgeon diagnosis in the clinical differentiation of metopic craniosynostosis and benign metopic ridge

Metopic suture closure can manifest as a benign metopic ridge (BMR), a variant of normal, to “true” metopic craniosynostosis (MCS), which is associated with severe trigonocephaly. Currently, there is no gold standard for how much associated orbitofrontal dysmorphology should trigger surgical intervention. In our study, we used three-dimensional (3D) curvature analysis to separate the phenotypes along the spectrum, and to compare surgeons’ thresholds for operation. Three-dimensional curvature analyses on 43 subject patients revealed that the mean curvature of mid-forehead vertical ridge was higher for patients who underwent operation than those who did not undergo operation by 1.3 m⁻¹ (p < 0.0001). In addition, these patients had more retruded supraorbital areas by −16.1 m⁻¹ (p < 0.0001). K-means clustering classified patients into two different severity groups, and with the exception of 2 patients, the algorithm’s classification of deformity completely agreed with the surgeons’ decisions to offer either conservative or operative therapy (i.e. 96% agreement). The described methods are effective in classifying severity of deformity and in our experience closely approximate surgeon therapeutic decision making. These methods offer the possibility to consistently determine when surgical intervention may be beneficial and to avoid unnecessary surgeries on children with benign metopic ridge and associated minimal orbitofrontal deformity.

Correcting B0 Field Distortions in MRI Caused by Stainless Steel Orthodontic Appliances at 1.5 T Using Permanent Magnets - A Head Phantom Study

Susceptibility artifacts caused by stainless steel orthodontic appliances (braces) pose significant challenges in clinical brain MRI examinations. We introduced field correction device (FCD) utilizing permanent magnets to cancel the induced B₀ inhomogeneity and mitigate geometric distortions in MRI. We evaluated a prototype FCD using a 3D-printed head phantom in this proof of concept study. The phantom was compartmented into anterior frontal lobe, temporal lobe, fronto-parieto-occipital lobe, basal ganglia and thalami, brain stem, and cerebellum and had built-in orthogonal gridlines to facilitate the quantification of geometric distortions and volume obliterations. Stainless steel braces were mounted on dental models of three different sizes with total induced magnetic moment 0.15 to 0.17 A·m². With braces B₀ standard deviation (SD) ranged from 2.8 to 3.7 ppm in the temporal and anterior frontal lobes vs. 0.2 to 0.3 ppm without braces. The volume of brain regions in diffusion weighted imaging was obliterated by 32–38% with braces vs. 0% without braces in the cerebellum. With the FCD the SD of B₀ ranged from 0.3 to 1.2 ppm, and obliterated volume ranged from 0 to 6% in the corresponding brain areas. These results showed that FCD can effectively decrease susceptibility artifacts from orthodontic appliances.

3D-Printed Models of Cleft Lip and Palate for Surgical Training and Patient Education

Background:

Sculpted physical models and castings of the anatomy of cleft lip and palate are used for parent, patient, and trainee education of cleft lip and palate conditions. In this study, we designed a suite of digital 3-dimensional (3D) models of cleft lip and palate anatomy with additive manufacturing techniques for patient education.

Methods:

CT scans of subjects with isolated cleft palate, unilateral and bilateral cleft lip and palate, and a control were obtained. Soft tissue and bony structures were segmented and reconstructed into digital 3D models. The oral soft tissues overlying the cleft palate were manually molded with silicone putty and scanned using CT to create digital 3D models. These were then combined with the original model to integrate with segmentable soft tissues. Bone and soft tissues were 3D printed in different materials to mimic the rigidity/softness of the relevant anatomy. These models were presented to the parents/patients at our craniofacial clinic. Visual analog scale (VAS) surveys were obtained pertaining to the particular use of the models, to ascertain their value in parental education.

Results:

A total of 30 parents of children with cleft conditions completed VAS evaluations. The models provided the parents with a better understanding of their child’s condition with an overall evaluation score of 9.35 ± 0.5.

Conclusions:

We introduce a suite of 3D-printed models of cleft conditions that has a useful role in patient, parental, and allied health education with highly positive feedback.

The role of Nasoalveolar molding: A 3D Prospective analysis

Nasoalveolar molding (NAM) is commonly employed to reduce the alveolar segments into proper alignment and to improve nasal symmetry in patients with cleft lip and palate. This study examines the periodical progression of NAM treatment over time. 20 patients with complete unilateral cleft lip and palate were prospectively recruited. A 2 stage NAM treatment protocol was applied. Stage 1 involved adjustment of the alveolar segments (mean age 15.6 days), while Stage 2 added nasal stents and started average 43 days after stage 1. 3D images (n = 241) were obtained prior to NAM initiation and weekly until the end of treatment. The cleft lip area, bilateral nostril areas, and the nostril height and width were measured. Treatment was assessed in the Cleft (C) side and the Non-cleft (N). There was significant difference in the C/N ratio of the nostril area, width, and height at pre-treatment (0.9 ± 0.3, 4.1 ± 1.1, and 0.5 ± 0.2), at the end of stage 1 (1.1 ± 0.3, 2.2 ± 0.6, and 0.8 ± 0.2), and at the end of stage 2 treatment (1.8 ± 0.3, 1.8 ± 0.4, and 1.2 ± 0.1); p < 0.05. Comparative 3D analysis with dense sampling offers a precise methodology for showing effects of NAM treatment. The morphological changes achieved with NAM therapy occur in early treatment phase.

Liquid Latex Molding: A Novel Application of 3D Printing to Facilitate Flap Design

The approach to bony craniofacial reconstruction has been significantly enhanced with the development of patient-specific, computer-aided designed and manufactured (CAD/CAM) implants. This technology, however, has not yet been widely employed for soft tissue reconstruction. While algorithmic approaches based on the size, location, and etiology of the defect are effective in most cases, a patient-specific CAD/CAM approach has benefits in complex reconstructive problems. In this study, we present a patient-specific approach to preoperative flap planning: using three-dimensional (3D) printing and liquid latex to create a flexible model of a flap, and demonstrate its application in planning a complex scalp reconstruction.

Three-dimensional changes in head shape after extended sagittal strip craniectomy with wedge ostectomies and helmet therapy

OBJECTIVE Outcome studies for sagittal strip craniectomy have largely relied on the 2D measure of the cephalic index (CI) as the primary indicator of head shape. The goal of this study was to measure the 2D and 3D changes in head shape that occur after sagittal strip craniectomy and postoperative helmet therapy. METHODS The authors performed a retrospective review of patients treated with sagittal strip craniectomy at their institution between January 2012 and October 2015. Inclusion criteria were as follows: 1) isolated sagittal synostosis; 2) age at surgery < 200 days; and 3) helmet management by a single orthotist. The CI was calculated from 3D images. Color maps and dot maps were generated from 3D images to demonstrate the regional differences in the magnitude of change in head shape over time. RESULTS Twenty-one patients met the study inclusion criteria. The mean CI was 71.9 (range 63.0-77.9) preoperatively and 81.1 (range 73.0-89.8) at the end of treatment. The mean time to stabilization of the CI after surgery was 57.2 ± 32.7 days. The mean maximum distances between the surfaces of the preoperative and 1-week postoperative and between the surfaces of the preoperative and end-of-treatment 3D images were 13.0 ± 4.1 mm and 24.71 ± 6.83 mm, respectively. The zone of maximum change was distributed equally in the transverse and vertical dimensions of the posterior vault. CONCLUSIONS The CI normalizes rapidly after sagittal strip craniectomy (57.2 days), with equal distribution of the change in CI occurring before and during helmet therapy. Three-dimensional analysis revealed significant vertical and transverse expansion of the posterior cranial vault. Further studies are needed to assess the 3D changes that occur after other sagittal strip craniectomy techniques.

Postural orientation and equilibrium processes associated with increased postural sway in autism spectrum disorder (ASD)

Background

Increased postural sway has been repeatedly documented in children with autism spectrum disorder (ASD). Characterizing the control processes underlying this deficit, including postural orientation and equilibrium, may provide key insights into neurophysiological mechanisms associated with ASD. Postural orientation refers to children’s ability to actively align their trunk and head with respect to their base of support, while postural equilibrium is an active process whereby children coordinate ankle dorsi-/plantar-flexion and hip abduction/adduction movements to stabilize their upper body. Dynamic engagement of each of these control processes is important for maintaining postural stability, though neither postural orientation nor equilibrium has been studied in ASD.

Methods

Twenty-two children with ASD and 21 age and performance IQ-matched typically developing (TD) controls completed three standing tests. During static stance, participants were instructed to stand as still as possible. During dynamic stances, participants swayed at a comfortable speed and magnitude in either anterior-posterior (AP) or mediolateral (ML) directions. The center of pressure (COP) standard deviation and trajectory length were examined to determine if children with ASD showed increased postural sway. Postural orientation was assessed using a novel virtual time-to-contact (VTC) approach that characterized spatiotemporal dimensions of children’s postural sway (i.e., body alignment) relative to their postural limitation boundary, defined as the maximum extent to which each child could sway in each direction. Postural equilibrium was quantified by evaluating the amount of shared or mutual information of COP time series measured along the AP and ML directions.

Results

Consistent with prior studies, children with ASD showed increased postural sway during both static and dynamic stances relative to TD children. In regard to postural orientation processes, children with ASD demonstrated reduced spatial perception of their postural limitation boundary towards target directions and reduced time to correct this error during dynamic postural sways but not during static stance. Regarding postural equilibrium, they showed a compromised ability to decouple ankle dorsi-/plantar-flexion and hip abduction/adduction processes during dynamic stances.

Conclusions

These results suggest that deficits in both postural orientation and equilibrium processes contribute to reduced postural stability in ASD. Specifically, increased postural sway in ASD appears to reflect patients’ impaired perception of their body movement relative to their own postural limitation boundary as well as a reduced ability to decouple distinct ankle and hip movements to align their body during standing. Our findings that deficits in postural orientation and equilibrium are more pronounced during dynamic compared to static stances suggests that the increased demands of everyday activities in which children must dynamically shift their COP involve more severe postural control deficits in ASD relative to static stance conditions that often are studied. Systematic assessment of dynamic postural control processes in ASD may provide important insights into new treatment targets and neurodevelopmental mechanisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s11689-016-9178-1) contains supplementary material, which is available to authorized users.

Dynamic facial asymmetry in patients with repaired cleft lip using 4D imaging (video stereophotogrammetry)

BACKGROUND

Unilateral cleft lip is a profoundly asymmetrical condition affecting all hard and soft tissue layers from the nose to the upper lip. Although the asymmetry is minimized through cleft lip repair, a degree of asymmetry inevitably persists. Studies investigating asymmetry in patients with cleft lip have used facial measurements, and static 2D and 3D photography. The nose/lip/mouth area, however, is rarely static in our day to day social interactions.

METHODS

Non-syndromic patients with cleft lip and palate, and a control group without orofacial clefts underwent 50 frames per second 4D imaging while generating facial expressions including smiling and pouting. Key landmarks were tracked throughout the expression, corrected for head movement and a motion path of each landmark was generated. Asymmetry was assessed for both extent of displacement, using Euclidean distances between frames, and the shape of the motion path using Procrustes analysis.

RESULTS

Twelve patients were compared in each group with an age range from 8 to 18. Comparing the motion path of key landmarks in the upper lip demonstrated statistically significant differences in both the magnitude and shape of motion during smiling and pouting between cleft and non-cleft groups.

CONCLUSION

Video stereophotogrammetry of the repaired cleft lip demonstrates asymmetry of both the magnitude of motion as well as asymmetry of the path of the motion itself. This may be due to the effect of the scar tissue from the repair, from the abnormal anatomy involved with cleft lip or a combination of the two.

Ionizing Radiation in Craniofacial Surgery: A Primer on Dose and Risks

An understanding of radiation dose and the anticipated risk to the patient is an important aspect of ordering radiological imaging studies responsibly. It is especially true for the pediatric practitioner because children are more vulnerable to the biological effects of radiation, such as radiosensitivity, longer lifetime years, and higher cellular mitotic activity. The use of fluoroscopy and computed tomography is commonplace in the practice of craniofacial surgery, but often dose reports from varied investigations are not directly comparable, and the risk of patient harm from the investigation is unclear. This article presents the fundamentals of radiation, dose, and risk as it applies to radiological imaging and also introduces our low dose craniofacial computed tomography protocol.

A noninvasive tumor oxygenation imaging strategy using magnetic resonance imaging of endogenous blood and tissue water

PURPOSE

To present a novel imaging strategy for noninvasive measurement of tumor oxygenation using MR imaging of endogenous blood and tissue water.

THEORY AND METHODS

The proposed approach for oxygen partial pressure (pO2) estimation is based on intravoxel incoherent motion diffusion MRI and the dependence of the blood R2 relaxation rate on the inter-echo spacing measured using a multiple spin-echo Carr-Purcell-Meiboom-Gill sequence and weak-field diffusion model. The accuracy of the approach was validated by comparison with (19)F MRI oximetry.

RESULTS

The results in eight rats at 4.7 T showed that tumors have longer T1 (1980 ± 186 ms) and T2 (59 ± 9 ms) relaxation times, heterogeneous blood volume fraction (0.23 ± 0.1), oxygen saturation level (Y) (0.53 ± 0.12), and pO2 (36 ± 15 mmHg) distributions compared with normal muscle (T1 1480 ± 86 ms, T2 29 ± 2 ms, blood volume fraction 0.22 ± 0.03, Y 0.49 ± 0.06, and pO2 39 ± 5 mmHg). pO2 estimates based on the novel (1)H approach were essentially identical with (19)F observations.

CONCLUSION

The study indicates that noninvasive measurement of tumor pO2 using (1)H MRI derived multiparametric maps is feasible and could become a valuable tool to evaluate tumor hypoxia.

Dynamic oxygen challenge evaluated by NMR T1 and T2*--insights into tumor oxygenation

There is intense interest in developing non-invasive prognostic biomarkers of tumor response to therapy, particularly with regard to hypoxia. It has been suggested that oxygen sensitive MRI, notably blood oxygen level-dependent (BOLD) and tissue oxygen level-dependent (TOLD) contrast, may provide relevant measurements. This study examined the feasibility of interleaved T2*- and T1-weighted oxygen sensitive MRI, as well as R2* and R1 maps, of rat tumors to assess the relative sensitivity to changes in oxygenation. Investigations used cohorts of Dunning prostate R3327-AT1 and R3327-HI tumors, which are reported to exhibit distinct size-dependent levels of hypoxia and response to hyperoxic gas breathing. Proton MRI R1 and R2* maps were obtained for tumors of anesthetized rats (isoflurane/air) at 4.7 T. Then, interleaved gradient echo T2*- and T1-weighted images were acquired during air breathing and a 10 min challenge with carbogen (95% O2 -5% CO2). Signals were stable during air breathing, and each type of tumor showed a distinct signal response to carbogen. T2* (BOLD) response preceded T1 (TOLD) responses, as expected. Smaller HI tumors (reported to be well oxygenated) showed the largest BOLD and TOLD responses. Larger AT1 tumors (reported to be hypoxic and resist modulation by gas breathing) showed the smallest response. There was a strong correlation between BOLD and TOLD signal responses, but ΔR2* and ΔR1 were only correlated for the HI tumors. The magnitude of BOLD and TOLD signal responses to carbogen breathing reflected expected hypoxic fractions and oxygen dynamics, suggesting potential value of this test as a prognostic biomarker of tumor hypoxia.

Evaluation of tumor ischemia in response to an indole-based vascular disrupting agent using BLI and (19)F MRI

Vascular disrupting agents (VDAs) have been proposed as an effective broad spectrum approach to cancer therapy, by inducing ischemia leading to hypoxia and cell death. A novel VDA (OXi8007) was recently reported to show rapid acute selective shutdown of tumor vasculature based on color-Doppler ultrasound. We have now expanded investigations to noninvasively assess perfusion and hypoxiation of orthotopic human MDA-MB-231/luc breast tumor xenografts following the administration of OXi8007 based on dynamic bioluminescence imaging (BLI) and magnetic resonance imaging (MRI). BLI showed significantly lower signal four hours after the administration of OXi8007, which was very similar to the response to combretastatin A-4P (CA4P), but the effect lasted considerably longer, with the BLI signal remaining depressed at 72 hrs. Meanwhile, control tumors exhibited minimal change. Oximetry used (19)F MRI of the reporter molecule hexafluorobenzene and FREDOM (Fluorocarbon Relaxometry using Echo Planar Imaging for Dynamic Oxygen Mapping) to assess pO2 distributions during air and oxygen breathing. pO2 decreased significantly upon the administration of OXi8007 during oxygen breathing (from 122 ± 64 to 34 ± 20 Torr), with further decrease upon switching the gas to air (pO2 = 17 ± 9 Torr). pO2 maps indicated intra-tumor heterogeneity in response to OXi8007, though ultimately all tumor regions became hypoxic. Both BLI and FREDOM showed the efficacy of OXi8007. The pO2 changes measured by FREDOM may be crucial for future study of combined therapy.

Phosphatidylserine-targeted molecular imaging of tumor vasculature by magnetic resonance imaging

Phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, becomes exposed on the outer surface of viable endothelial cells in tumor vasculature, but not in normal blood vessels. In the present study, we report the use of PGN635, a novel human monoclonal antibody that specifically targets PS, for in vivo molecular MRI of tumor vasculature. The F(ab')2 fragments of PGN635 were conjugated to polyethylene glycol (PEG) coated iron oxide nanoparticles (IO). Targeting specificity of the PS-targeted Nanoprobe, IO-PGN635F(ab')2 was first confirmed by in vitro MRI and histological staining. In vivo longitudinal MRI was then performed before and after i.v. injection of IO-PGN635F(ab')2 into mice bearing 4T1 breast tumors. T2-weighted MR images at 9.4 T revealed inhomogeneous signal loss in tumor as early as 2 h post injection. Furthermore, ionizing radiation induced a significant increase in PS exposure on tumor vascular endothelial cells, resulting in significantly enhanced and sustained tumor contrast (p < 0.05). Spatially heterogeneous MRI contrast correlated well with histological staining of tumor vascular endothelium. Our studies suggest that PS exposed within the lumen of tumor vasculature is a highly specific and useful biomarker for targeted MRI contrast agents.

Correlations of noninvasive BOLD and TOLD MRI with pO2 and relevance to tumor radiation response

PURPOSE

To examine the potential use of blood oxygenation level dependent (BOLD) and tissue oxygenation level dependent (TOLD) contrast MRI to assess tumor oxygenation and predict radiation response.

METHODS

BOLD and TOLD MRI were performed on Dunning R3327-AT1 rat prostate tumors during hyperoxic gas breathing challenge at 4.7 T. Animals were divided into two groups. In Group 1 (n = 9), subsequent (19) F MRI based on spin lattice relaxation of hexafluorobenzene reporter molecule provided quantitative oximetry for comparison. For Group 2 rats (n = 13) growth delay following a single dose of 30 Gy was compared with preirradiation BOLD and TOLD assessments.

RESULTS

Oxygen (100%O2 ) and carbogen (95%O2 /5%CO2 ) challenge elicited similar BOLD, TOLD and pO2 responses. Strong correlations were observed between BOLD or R2* response and quantitative (19) F pO2 measurements. TOLD response showed a general trend with weaker correlation. Irradiation caused a significant tumor growth delay and tumors with larger changes in TOLD and R1 values upon oxygen breathing exhibited significantly increased tumor growth delay.

CONCLUSION

These results provide further insight into the relationships between oxygen sensitive (BOLD/TOLD) MRI and tumor pO2 . Moreover, a larger increase in R1 response to hyperoxic gas challenge coincided with greater tumor growth delay following irradiation.

Simultaneous measurement of tissue oxygen level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) effects in abdominal tissue oxygenation level studies

PURPOSE

To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1 - and T2*-maps serially during a single dynamic MRI scan in response to an oxygen challenge.

MATERIALS AND METHODS

The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge.

RESULTS

Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs.

CONCLUSION

The free-breathing respiratory-triggered interleaved T1 and T2* sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and T2* data within the abdomen.

Oxygenation in cervical cancer and normal uterine cervix assessed using blood oxygenation level-dependent (BOLD) MRI at 3T

Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T₂*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R₂* measurements. The baseline T₂*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R₂* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined.

Dual 19F/1H MR gene reporter molecules for in vivo detection of β-galactosidase

Increased emphasis on personalized medicine and novel therapies requires the development of noninvasive strategies for assessing biochemistry in vivo. The detection of enzyme activity and gene expression in vivo is potentially important for the characterization of diseases and gene therapy. Magnetic resonance imaging (MRI) is a particularly promising tool, since it is noninvasive and has no associated radioactivity, yet penetrates deep tissue. We now demonstrate a novel class of dual (1)H/(19)F nuclear magnetic resonance (NMR) lacZ gene reporter molecule to specifically reveal enzyme activity in human tumor xenografts growing in mice. We report the design, synthesis, and characterization of six novel molecules and evaluation of the most effective reporter in mice in vivo. Substrates show a single (19)F NMR signal and exposure to β-galactosidase induces a large (19)F NMR chemical shift response. In the presence of ferric ions, the liberated aglycone generates intense proton MRI T(2) contrast. The dual modality approach allows both the detection of substrate and the imaging of product enhancing the confidence in enzyme detection.

In vitro verification of multiple-receiver Doppler ultrasound for velocity estimation improvement

The coherent scattering effect, which introduces noise in Doppler-derived velocity estimates, is caused by constructive and destructive interference of sound waves scattered from multiple particles. Because the phase relationship between signals scattered from different particles depends on the orientation of the receiver, the error in a given velocity estimate depends on the receiver location. To examine this dependence, the velocity of a steady uniform flow was measured simultaneously with a transceiver and three receivers, and the cross-correlation coefficients between velocity estimates for pairs of crystals were calculated. The velocity estimates were nearly independent, with cross-correlation coefficients of approximately 0.2. This result agrees with our previously published numerical simulation studies which demonstrated that the coherent scattering noise in receivers separated by 5 degrees or more was nearly uncorrelated. Consequently, the contribution of coherent scattering noise can be reduced by averaging out noise in signals obtained from multiple receivers.