MRI for the evaluation of pectus excavatum

Utility of White Light Scanning as an Alternative to Computed Tomography to Evaluate Severity of Pectus Excavatum Deformity

BACKGROUND

Pectus excavatum (PE) severity and surgical candidacy are determined by computed tomography (CT)-delineated Haller Index (HI) and Correction Index (CI). White light scanning (WLS) has been proposed as a non-ionizing alternative. The purpose of this retrospective study is to create models to determine PE severity using WLS as a non-ionizing alternative to CT.

METHODS

Between November 2015 and February 2023, CT and WLS were performed for children ≤18 years undergoing evaluation at a high-volume, chest-wall deformity clinic. Separate quadratic discriminate analysis models were developed to predict CT HI ≥ 3.25 and CT CI ≥ 28% indicating surgical candidacy. Two bootstrap forest models were trained on WLS measurements and patient demographics to predict CT HI and CT CI values then compared to actual index values by intraclass correlation coefficient (ICC).

RESULTS

In total, 242 patients were enrolled (86.4% male, mean [SD] age 15.2 [1.3] years). Quadratic discriminate analysis models predicted CT HI ≥ 3.25 with specificity = 91.7%, PPV = 97.7% (AUC = 0.91), and CT CI ≥ 28% with specificity = 92.3%, PPV = 93.5% (AUC = 0.84). Bootstrap forest model predicted CT HI with training dataset ICC (95% CI) = 0.91 (0.88-0.93, R2 = 0.85) and test dataset ICC (95% CI) = 0.86 (0.71-0.94, R2 = 0.77). For CT CI, training dataset ICC (95% CI) = 0.91 (0.81-0.93, R2 = 0.86) and test dataset ICC (95% CI) = 0.75 (0.50-0.88, R2 = 0.63).

CONCLUSIONS

Using noninvasive and nonionizing WLS imaging, we can predict PE severity at surgical threshold with high specificity obviating the need for CT. Furthermore, we can predict actual CT HI and CI with moderate-excellent reliability. We anticipate this point-of-care tool to obviate the need for most cross-sectional imaging during surgical evaluation of PE.

LEVEL OF EVIDENCE

Level III.

STUDY TYPE

Study of Diagnostic Test.

Description of a new clinical syndrome: thoracic constriction without evidence of the typical funnel-shaped depression-the "invisible" pectus excavatum

Pectus excavatum (PE) is a congenital malformation with a funnel-shaped depression of the sternum that can lead to cardiac symptoms. However, there are patients with thoracic constriction (defined as elevated Haller-Index > 3.25 determined by cardiac magnetic resonance imaging (CMR)) without visible evidence of PE, leading to similar complaints. Between January 2004 till June 2020, patients who underwent CMR for further evaluation of the heart, due to cardiac symptoms were enrolled and compared to controls. Biventricular global strain analysis was assessed using feature tracking (CMR-FT). ECG and/or Holter recordings were performed to detect rhythm events. Cardiac symptoms were evaluated in detail using a questionnaire. Finally, 88 patients (male 35, female 53) with elevated Haller-Index (3.9 ± 0.8) were included and compared to CMR data from 25 individuals with confirmed PE and 25 healthy controls (HC). Mean age at time of CMR was 35 ± 16 years. The most common symptoms at presentation were palpitations (41%), followed by dyspnea (24%) and atypical chest pain (14%). Three patients (3%) had atrial fibrillation or atrial flutter. Concomitant phenomena were pericardial effusion in 39% and mitral valve prolapse (MVP) in 27% of the study cohort. While there were no differences in left ventricular function or volumes, right ventricular function (RVEF) was significantly lower in patients with internal PE compared to HC (RVEF (%) 50 ± 5 vs 59 ± 4, p < 0.01). Strain analysis revealed only discrete changes in RV strain, implying a purely mechanical problem in the absence of structural changes. RV dimensions were negatively correlated with the size of thoracic indices (r = 0.41), reflecting the extent of thoracic constriction. MVP was more prevalent in patients with greater thoracic indices (r = 0.24). The described cohort, referred to as internal PE because of the absence of external changes, showed similar CMR morphologic findings as patients with real PE (especially altered dimensions of the right heart and a lower RVEF). In addition, there was a high incidence of rhythm disturbances, such as extrasystoles or arrhythmias. In one-third of the study cohort additional abnormalities such as pericardial effusion or MVP were present, with MVP being found more frequently in patients with larger thoracic indices, suggesting a possible common pathogenesis.Trial registration: ISRCTN registry, ISRCTN15355937, retrospectively registered 03.06.2022, https://www.isrctn.com/ISRCTN15355937?q=15355937&filters=&sort=&offset=1&totalResults=1&page=1&pageSize=10 .

Association of Pectus Excavatum With Ventricular Remodelling and Mitral Valve Abnormalities in Marfan Syndrome

Background: Marfan syndrome (MFS) is an inherited connective tissue disorder. Pectus excavatum (PEX) is common in MFS. The purpose was to evaluate the association of PEX with cardiovascular manifestations of MFS, biventricular size and function. Methods: MFS adults undergoing cardiac MRI were retrospectively evaluated. Exclusion criteria were incomplete cardiac MRI, significant artifacts, co-existent ischaemic or congenital heart disease. Haller Index (HI) ≥3.25 classified patients as PEX positive (PEX+) and PEX negative (PEX-). Cardiac MRI analysis included assessment of mitral valve prolapse (MVP), mitral annular disjunction (MAD), biventricular volumetry and aortic dimensions. Results: 212 MFS patients were included, 76 PEX+ and 136 PEX- (HI 8.3 ± 15.2 vs 2.3 ± 0.5, P < .001). PEX+ were younger (33.4 ± 12.0 vs 38.1 ± 14.3 years, P = .02) and similar in sex distribution (55% vs 63% male, P = .26) compared to PEX-. MVP and MAD were more frequent in PEX+ vs PEX- (43/76 [57%] vs 37/136 [27%], P < .001; 44/76 [58%] vs 50/136[37%], P = .003, respectively). PEX+ had higher right ventricular end-diastolic and end-systolic volumes (RVEDVi 92 ± 17mL/m2 vs 84 ± 22mL/m2, P = .04; RVESVi 44 ± 10 mL/m2 vs 39 ± 14 mL/m2, P = .02), lower RV ejection fraction (RVEF 52 ± 5% vs 55 ± 6%, P = .01) compared to PEX-. Left ventricular (LV) volumes, LVEF and aortic dimensions were similar. Conclusion: MFS adults with PEX have higher frequency of cardiac manifestations including MV abnormalities, increased RV volumes and lower RVEF compared to those without PEX. Awareness of this association is important for all radiologists who interpret aortic CT or MRI, where HI can be easily measured. PEX in MFS may suggest more severe disease expression necessitating careful screening for MV abnormalities and outcomes surveillance.

A new tool for assessing Pectus Excavatum by a semi-automatic image processing pipeline calculating the classical severity indexes and a new marker: the Volumetric Correction Index

Background

In clinical assessment of Pectus Excavatum (PE), the indication to surgery is based not only on symptoms but also on quantitative markers calculated from Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scans. According to clinical routine, these indexes are measured manually by radiologists with limited computer support. This process is time consuming and potentially subjected to inaccuracy and individual variability in measurements. Moreover, the existing indexes have limitations, since they are based on linear measurements performed on single slices rather than on volumetric data derived from all the thoracic scans.

Results

In this paper we present an image processing pipeline aimed at providing radiologists with a computer-aid tool in support of diagnosis of PE patients developed in MATLAB® and conceived for MRI images. This framework has a dual purpose: (i) to automatize computation of clinical indexes with a view to ease and standardize pre-operative evaluation; (ii) to propose a new marker of pathological severity based on volumetric analysis and overcoming the limitations of existing axial slice-based indexes. Final designed framework is semi-automatic, requiring some user interventions at crucial steps: this is realized through a Graphical User Interface (GUI) that simplifies the interaction between the user and the tools. We tested our pipeline on 50 pediatric patients from Gaslini Children’s Hospital and performed manual computation of indexes, comparing the results between the proposed tool and gold-standard clinical practice. Automatic indexes provided by our algorithm have shown good agreement with manual measurements by two independent readers. Moreover, the new proposed Volumetric Correction Index (VCI) has exhibited good correlation with standardized markers of pathological severity, proving to be a potential innovative tool for diagnosis, treatment, and follow-up.

Conclusions

Our pipeline represents an innovative image processing in PE evaluation, based on MRI images (radiation-free) and providing the clinician with a quick and accurate tool for automatically calculating the classical PE severity indexes and a new more comprehensive marker: the Volumetric Correction Index.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-022-00754-0.

Society for Cardiovascular Magnetic Resonance 2020 Case of the Week series

The Society for Cardiovascular Magnetic Resonance (SCMR) is an international society focused on the research, education, and clinical application of cardiovascular magnetic resonance (CMR). Case of the week is a case series hosted on the SCMR website ( https://www.scmr.org ) that demonstrates the utility and importance of CMR in the clinical diagnosis and management of cardiovascular disease. Each case consists of the clinical presentation and a discussion of the condition and the role of CMR in diagnosis and guiding clinical management. The cases are all instructive and helpful in the approach to patient management. We present a digital archive of the 2020 Case of the Week series of 11 cases as a means of further enhancing the education of those interested in CMR and as a means of more readily identifying these cases using a PubMed or similar search engine.

Analysis of chest wall elevation after the Nuss procedure using 3D body scanning technique in patients with pectus excavatum

PURPOSE

For the evaluation of the chest wall deformity, we adopted a non-invasive 3D body scanning system. The objective of this study is to evaluate surgical effect on the whole thorax using 3D scanning technique before and after Nuss procedure.

METHODS

We performed 3D body scanning using Structure Sensor (Occipital Inc, USA) in 11 symmetric patients (average age 13 ± 3.2) under general anesthesia before and after Nuss procedure. Using the scanned data, the improved chest wall was analyzed using 3D-Rugle (Medic Engineering, Japan) imaging software. Preoperative and postoperative 3D data were super-imposed and a thoracic elevating distance in the line of the axial and sagittal section through the deepest point was calculated. Pre- and postoperative external sternal angle (ESA) were calculated from the scanned data.

RESULTS

Mean thoracic elevation distance at the deepest point was 38.6 ± 6.1 mm and it was 28.4 ± 5.1 mm and 19.4 ± 4.9 mm at 4 cm and 8 cm cranial side, respectively. Average ESA improved from 3.9 ± 1.6 degrees to 15.0 ± 1.1 degrees after the operation.

CONCLUSION

Chest depression was effectively elevated 39 mm at the deepest point after Nuss procedure. An indirect elevation effect by pectus bars was found on the wide area of the anterior chest.

External caliper-based measurements of the modified percent depth as an alternative to cross-sectional imaging for assessing the severity of pectus excavatum

BACKGROUND

Cross-sectional imaging (CSI) may be clinically unnecessary in the evaluation of pectus excavatum (PE). The purpose of our study was to prospectively evaluate the accuracy and reliability of the modified percent depth (MPD), derived from caliper-based external measurements, in identifying PE.

METHODS

Children 11-21 years old presenting for evaluation of PE or to obtain thoracic cross-sectional imaging for other indications were measured to derive the Modified Percent Depth. The Haller Index (HI) and Correction Index (CI) were calculated from CSI. Receiver-Operator Characteristic (ROC) analysis was used to compare the sensitivity and specificity of MPD, HI, and CI. Interrater reliability was assessed using Spearman's correlation coefficient and Cohen's Kappa coefficient.

RESULTS

Of 199 patients, 76 (38%) had severe PE. Median age was 16 years (range = 11-21). The median Modified Percent Depth was 21.4% (IQR = 16.2-26.3) among those with PE versus 4.1% (IQR = 1.7-6.4) in those without (p < 0.001). MPD ≥ 11% exhibited similar sensitivity and specificity to HI ≥ 3.25 and CI ≥ 10 for identifying PE (ROC 0.98 vs. 0.97 vs. 0.98, respectively, p = 0.41). With respect to interrater reliability, independent clinicians' caliper measurements exhibited 87% agreement when identifying MPD ≥ 11% (p < 0.001) with excellent correlation (Spearman's ρ > 0.71, p < 0.001).

CONCLUSION

Caliper-based, physical examination measurements of the Modified Percent Depth reliably identify pectus excavatum and represent an alternative to CSI-based measurements for the assessment of PE.

TYPE OF STUDY

Diagnostic test.

LEVEL OF EVIDENCE

Level II.

Physician-Estimated Depth as a Screening Tool for Computed Tomography Evaluation of Pectus Excavatum

BACKGROUND

Pectus excavatum (PE) is the most common congenital chest wall anomaly with a reported incidence of 1/300 to 1/400 live births and a male predominance. Preoperative evaluation of defect severity typically requires a calculation of the Haller index (HI) and/or correction index (CI) using computed tomography (CT) or x-rays. The purpose of this study was to determine whether physician-estimated depth (PED), a bedside screening tool, could be used to identify a subset of pediatric patients in whom CT was unnecessary.

METHODS

After institutional review board approval (IRB #032018-091), we retrospectively reviewed all patients with a diagnosis of PE between 2009 and 2018 at our academic pediatric center. Demographic information including age, sex, and body mass index were abstracted. Imaging was reviewed to obtain HI and CI and to retrospectively calculate PED. The PED is calculated at the bedside by measuring the depth of the pectus at the site of greatest depression relative to a horizontal surface laid across the deformity. For this retrospective study, we calculated the CT-derived PED by measuring the depth from the horizontal on the respective CT images. Patients without imaging studies and patients with pectus carinatum, arcuatum, or mixed deformities were excluded from this study.

RESULTS

A total of 94 patients met inclusion criteria. Of these, 82% were male, with a median age of 15 y. Patients were further subdivided by BMI, with 46% of patients having a BMI of <18.5 kg/m² (i.e., underweight), whereas 54% of patients had a BMI of ≥18.5 kg/m². Using a threshold PED of 2 cm, patients with a BMI of <18.5 kg/m² had correct classification rates of 93% and 95% using PED relative to HI and CI, respectively. Patients with a BMI of ≥18.5 kg/m² had correct classification rates of 80% and 88% using PED relative to HI and CI, respectively, at the same 2 cm threshold.

CONCLUSIONS

PED is a viable screening tool for the preoperative evaluation of PE with a 2 cm threshold providing the combination of high sensitivity, specificity, and correct classification rates especially in underweight patients.

Comparison of magnetic resonance imaging and computed tomography to measure preoperative parameters of children with pectus excavatum

IMPORTANCE

Pectus excavatum (PE) is the most common thoracic wall deformity in children, we need a method which could be used to evaluate pulmonary functions and effects on development.

OBJECTIVE

To evaluate the use of 3D T1-weighted (3DT1) and mDIXON magnetic resonance imaging (MRI) sequences for measuring the thoracic parameters and morphology of children with PE, comparing the measurements with those made on computed tomography (CT).

METHODS

This is a retrospective study of children with thoracic deformities who were hospitalized at the Department of Thoracic Surgery of the Heart Center, Beijing Children's Hospital, between June 2014 and June 2015. Chest CT was performed first, with the MRI scanning then being performed 0-3 days later. The mDIXON sequences were obtained in inspiratory and expiratory phases and the 3DT1 sequences were obtained during free breathing. Thoracic volume was measured using the acquired images.

RESULTS

The lung volumes measured on mDIXON MRI and CT were highly correlated, with the Haller index not being significantly different between the two methods. Bland-Altman analyses showed that lung, cardiac, and retrosternal parameters were similar between the two methods. Pulmonary parameters were higher with the end-inspiratory phase mDIXON images than with the end-expiratory phase images, as expected, while cardiac parameters were unaffected by the respiratory phase.

INTERPRETATION

Thoracic volumes measured on mDIXON MRI in combination with held respiration could reflect lung volume functions and help in observing the movement functions of the lungs and heart. The method could be used instead of CT, avoiding subjecting the patient to potentially harmful radiation.

Quantification of pectus excavatum: Anatomic indices

Pectus excavatum is the most common chest wall deformity in children. The central portion of the chest is displaced posteriorly relative to the remainder of the anterior chest wall. Quantification of defect severity can be performed with multiple imaging modalities or external thoracic measures, but is most commonly quantified by the Haller Index (HI) or Pectus Correction Index (PCI). These two measures provide a measure of the chest based on cross sectional imaging, most commonly CT scans, allowing for standard comparison and definitions of pectus defects. The purpose of this article is to describe the creation, calculation, and limitations of the methods quantifying pectus defects.

Pectus updates and special considerations in Marfan syndrome

Congenital chest wall or pectus deformities including pectus excavatum (funnel chest) and pectus carinatum (pigeon chest) affect a significant proportion of the general population and up to 70% of patients with Marfan syndrome. Patients often experience significant morbidity and psychological distress, which can worsen with age. Here we discuss new techniques for both operative and non-operative treatment of pectus deformity, the importance of a welltimed intervention and special considerations in patients with Marfan syndrome.

Magnetic resonance imaging of the mediastinum, chest wall and pleura in children

The acceptance of applications for the use of chest MRI in children has been somewhat slow and selective. The use of MRI to image chest wall lesions is likely the most common and widely used indication, aside from the widespread and somewhat sophisticated use of MRI in imaging the cardiovascular structures of the chest. In this respect, fairly standard variations of T1-W, T2-W and contrast-enhanced imaging can be used, similar to the sequences used for musculoskeletal lesions elsewhere in the body. Imaging of the anterior mediastinal masses should be performed in conjunction with a detailed pre-test clinical examination to determine potential cardiovascular compromise. MRI in the setting of middle mediastinal adenopathy, congenital mediastinal cysts or posterior mediastinal masses, however, has been shown to be more effective and more comprehensive than multidetector CT. Although sonographic imaging is the initial modality of choice for pleural abnormalities, MR imaging is extremely effective and clinically useful in the setting of a potentially ambiguous sonographic examination. Faster imaging protocols are likely to increase the acceptance of MRI to replace multidetector CT for many pediatric chest lesions.

Pectus excavatum in adult women: repair and the impact of prior or concurrent breast augmentation

BACKGROUND

Women present with pectus excavatum five times less frequently than men. Adult women may have additional, associated cosmetic factors, including hypoplastic or asymmetric breasts, or prior augmentation. The authors evaluated the impact of prior or concurrent cosmetic breast surgery in an adult female cohort undergoing repair of pectus excavatum deformity.

METHODS

A retrospective review was performed of women (≥18 years old) who underwent pectus excavatum repair at a single institution from January of 2010 to September of 2013.

RESULTS

Pectus excavatum repair was performed on 47 women with a median age of 35 years (range, 18 to 63 years). Mean pectus severity index was 6.2 (range, 3.1 to 16). All patients had physiologic symptoms as the primary purpose for seeking repair. Twenty patients (43 percent) presented with existing implants or the desire for implants at the time of repair. Fifteen patients (32 percent) had a history of implant placement including prior breast augmentation (n = 14) and/or pectus implant (n = 4). Concurrent augmentation (n = 5), breast implant exchange (n = 8), and/or removal of chest wall implants (n = 4) was performed during repair. Morbidity included one implant-related hematoma. Complications and hospital stay were not significantly different for patients undergoing primary repair alone versus those with prior or concurrent augmentation.

CONCLUSIONS

Breast cosmesis was a concern in nearly half of adult women presenting for pectus excavatum repair. The authors' experience suggests neither prior nor concurrent breast augmentation increases the risk of complications in repair. The authors recommend that cosmetic breast surgery be performed concurrently with pectus excavatum repair.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

The incidental pulmonary nodule in a child. Part 2: Commentary and suggestions for clinical management, risk communication and prevention

The incidental detection of small lung nodules in children is a vexing consequence of an increased reliance on CT. We present an algorithm for the management of lung nodules detected on CT in children, based on the presence or absence of symptoms, the presence or absence of elements in the clinical history that might explain these nodules, and the imaging characteristics of the nodules (such as attenuation measurements within the nodule). We provide suggestions on how to perform a thoughtfully directed and focused search for clinically occult extrathoracic disease processes (including malignant disease) that may present as an incidentally detected lung nodule on CT. This algorithm emphasizes that because of the lack of definitive information on the natural history of small solid nodules that are truly detected incidentally, their clinical management is highly dependent on the caregivers' individual risk tolerance. In addition, we present strategies to reduce the prevalence of these incidental findings, by preventing unnecessary chest CT scans or inadvertent inclusion of portions of the lungs in scans of adjacent body parts. Application of these guidelines provides pediatric radiologists with an important opportunity to practice patient-centered and evidence-based medicine.

The communication of the radiation risk from CT in relation to its clinical benefit in the era of personalized medicine: part 2: benefits versus risk of CT

In order to personalize the communication of the CT risk, we need to describe the risk in the context of the clinical benefit of CT, which will generally be much higher, provided a CT scan has a well-established clinical indication. However as pediatric radiologists we should be careful not to overstate the benefit of CT, being aware that medico-legal pressures and the realities of health care economics have led to overutilization of the technology. And even though we should not use previously accumulated radiation dose to a child as an argument against conducting a clinically indicated scan (the "sunk-cost" bias), we should consider patients' radiation history in the diagnostic decision process. As a contribution to future public health, it makes more sense to look for non-radiating alternatives to CT in the much larger group of basically healthy children who are receiving occasional scans for widely prevalent conditions such as appendicitis and trauma than to attempt lowering CT use in the smaller group of patients with chronic conditions with a limited life expectancy. When communicating the CT risk with individual patients and their parents, we should acknowledge and address their concerns within the framework of informed decision-making. When appropriate, we may express the individual radiation risk, based on estimates of summated absorbed organ dose, as an order of magnitude rather than as an absolute number, and compare this with the much larger natural cancer incidence over a child's lifetime, and with other risks in medicine and daily life. We should anticipate that many patients cannot make informed decisions on their own in this complex matter, and we should offer our guidance while maintaining respect for patient autonomy. Proper documentation of the informed decision process is important for future reference. In concert with our referring physicians, pediatric radiologists are well-equipped to tackle the complexities associated with the communication of CT risk, a task that often falls upon us, and by becoming more involved in the diagnostic decision process we can add value to the health care system.

Pectus excavatum and MASS phenotype: an unknown association

INTRODUCTION

Severe pectus excavatum (PE) is a deep chest wall deformity that generates both a cosmetic damage and a cardiac/respiratory function impairment. Excluding the scarce reports on Marfan's syndrome (MFS) and Ehlers-Danlos's syndrome (EDS), few studies have examined the relation between severe PE and connective tissue disorders. The aim of this study is to verify the clinical significance of such correlation.

SUBJECTS AND METHODS

Ninety-two consecutive patients, of whom 79 were males, between 6 and 34 years old, classified as having severe PE, were seen at our institution from June 2005 to September 2010. All patients underwent clinical, ophthalmological, cardiac, and radiological (chest and spine magnetic resonance imaging) screening. The following features were observed: skin stretch marks, scoliosis, joint hypermobility, echocardiographic signs, spinal defects, and myopia.

RESULTS

Classical connectivopathies such as MFS or EDS were present in only 5 patients (approximately 5%), whereas a single deformity was present in 4. The largest group (approximately 71%) was represented by phenotypical alterations such as mitral valve prolapse, aortic root enlargement, and skeletal and skin alterations (MASS). Among those patients, the most frequent clinical manifestations were the skeletal ones, followed by skin marks and mitral valve prolapse.

CONCLUSIONS

PE showed an evident association with an array of features that we describe as MASS. Although not one of this subgroup of patients has been described with increased aortic root diameter when screened (a feature widely present in MFS patients), they probably would require a thorough and longer follow-up than those affected by isolated PE because of the potential occurrence of severe cardiovascular complications such as aneurysms and dissection, which are major causes of morbidity and mortality in MFS.