Diagnostic Imaging and Spirometry Case Studies

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Diagnostic Imaging and Spirometry Case Studies

Case 1

  1. What diagnosis must you always consider with this assessment finding?

The injury is believed to be a sprain because it does not usually cause a physical deformity, and no fracture is seen in the imaging studies.  The patient presented with pain, slight swelling, and limited movement due to the pain.

  1. What will be your treatment at this time? Is there further testing to be ordered?

Treatment includes ceasing all physical activity that can further aggravate the injury by immobilizing the joint with a splint. Pain medication should be given to reduce pain. Further testing should be done in a few days if the swelling has not reduced (Ramponi, Hoyt, & Ramirez, 2017). Diagnostic Imaging and Spirometry Case Studies.

  1. Are there any potential consequences of not treating this? If so, what?

According to Thomas and Paynter, (2018), there are complication if incorrect healing of the bones. Blood circulation impairment may lead to bone loss and arthritis. Complications will be resolved through surgery that will require proper position and secured with pins or wires to promote healing.

Case 2

  1. What diagnosis should you consider?

Acute Achilles Rupture due to posterior ankle with ecchymosis, mild edema, and decreased ROM due to pain. There was also tenderness at the Achilles tendon insertion site and a slight positive Thompson’s test. Diagnostic Imaging and Spirometry Case Studies.

  1. What imaging studies should you do?

Magnetic resonance imaging is the most preferred imaging studies.

  1. What treatment will you start now?

Operative repair by sewing the torn ends of the injured Achilles tendon together was considered to reducerisk of a future re-rupture.

  1. Are there any potential consequences of not treating this? If so, what?

Complications include tendon scarring and decreased range of motion and muscle weakness. Re-rupture isreduced in surgically repaired patients (Hutchison et al., 2015).

Case 3

  1. What imaging is appropriate for this patient?

An MRI or a CT scan can help rule out other medical conditions that may cause your symptoms, such as a brain tumor, an abscess, or a clot.

  1. What questions do you need to ask before ordering an MRI with contrast?

Ask the patient about Artificial eye or eyelid spring, presence of Ear (Cochlear) implant, middle ear implant Hearing aids, dentures,  implants or Body piercing, tattoo. Ask the patient about the existence of Cardiac pacemaker or implanted cardioverter defibrillator/ICD (Wattjes et al., 2016). Diagnostic Imaging and Spirometry Case Studies.

  1. How would you describe an MRI during patient education?

MRI machines are large and are tube-shaped magnets.  The patient will lie inside the device, and the magnetic field temporarily realigns water molecules in your body to form an image that differentiates bone and tissue.  It produces high-resolution images that help diagnose health problems.

Case 4

  1. What is the likely diagnosis?

Asthma with acute bronchitis since the patient has a history of asthma, but after a cold, the symptoms were triggered.

  1. What test would be appropriate in this patient?

Chest X-ray and blood test.

  1. How might the information obtained from testing be helpful to the practitioner?
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According to Sheldon wt al. (2018), a chest x-ray would be appropriate of the patient to check out the bronchus and bronchial to rule our pneumonia.  A blood test is also necessary to rule out bacterial infection.

  1. Would a chest X-ray be necessary for this patient? Why or why not?

A chest X-ray will be necessary for the patient so that the physician can visualize the respiratory tract and rule out any other diseases. It is essential since the patient is also a known asthmatic. Diagnostic Imaging and Spirometry Case Studies.

Case 5

  1. What is in your differential diagnosis?

Differential diagnoses include Chronic obstructive pulmonary disease (COPD), congestive heart failure, pneumonia, asthma, or allergic reactions.

  1. What test would be appropriate in this patient?

Tests such as CT scan, pulmonary function tests, an echocardiogram, and a complete blood count will be appropriate of the patient.

  1. How might the information obtained from testing be helpful to the nurse practitioner?

The tests will help the nurse to confirm the diagnosis based on the findings of each test. As a result, treatment can be started to relive the symptoms of the patient and to improve the quality of life of the patient (Farrugia Jones, 2017).

References

Farrugia Jones, C. (2017). Updates on the management of COPD.

Hutchison, A. M., Topliss, C., Beard, D., Evans, R. M., & Williams, P. (2015). The treatment of a rupture of the Achilles tendon using a dedicated management program. The bone & joint journal, 97(4), 510-515.

Ramponi, D. R., Hoyt, K. S., & Ramirez, E. G. (2017). Management of Hand Injuries: Part III. Advanced Emergency Nursing Journal, 39(2), 86-96. Diagnostic Imaging and Spirometry Case Studies.

Sheldon, G., Heaton, P. A., Palmer, S., & Paul, S. P. (2018). Nursing management of pediatric asthma in emergency departments. Emergency Nurse, 26(4).

Thomas, J., & Paynter, A. (2018). Assessment and management of common musculoskeletal injuries. Practice Nursing, 29(11), 521-525.

Wattjes, M. P., Wijburg, M. T., Vennegoor, A., Witte, B. I., Roosendaal, S. D., Sanchez, E., … & Barkhof, F. (2016). Diagnostic performance of brain MRI in pharmacovigilance of natalizumab-treated MS patients. Multiple Sclerosis Journal, 22(9), 1174-1183.

Chronic obstructive pulmonary disease (COPD) is a pathologic pulmonary condition characterized by expiratory airflow obstruction due to emphysematous destruction of the lung parenchyma and remodeling of the small airways. While spirometry is a very useful diagnostic tool for screening large groups of smokers, it cannot readily differentiate the etiologies of COPD and thus has limited utility in characterizing subjects for clinical and investigational purposes. There has been a longstanding interest in thoracic imaging and its role in the in-vivo characterization of smoking related lung disease. Research in this area has spanned readily available modalities such as chest x-ray and computed tomography to more advanced imaging techniques such as optical coherence tomography and magnetic resonance imaging. While chest x-ray is almost universally available, it lacks sensitivity in detecting both airway disease and mild emphysema, and is not generally amenable to objective analysis. Computed tomography has become the standard modality used for objective visualization of disease. Diagnostic Imaging and Spirometry Case Studies. It can provide useful measures of emphysema, airway disease, and more recently pulmonary vascular disease for clinical correlation. It does, however, face limitations in standardization across brands and generations of scanners, and the ionizing radiation associated with image acquisition is of concern to both patient and health care provider. Newer techniques such as OCT and MRI offer exciting in-vivo insight into lung structure and function that was previously available only in necropsy specimens and physiology labs. Given the more limited availability of these techniques, they are at present viewed as adjuncts to CT imaging.

Keywords: Emphysema, COPD, Imaging, computed tomography, airway disease

Chronic obstructive pulmonary disease (COPD) is a pathologic condition of the lung characterized by emphysematous destruction of the lung parenchyma and remodeling of the small airways. The admixture of these two processes leads to what is clinically observed as expiratory airflow obstruction that is not completely reversible with the use of inhaled bronchodilating medications.(1) Despite ongoing refinements in the spirometric classification of disease, marked heterogeneity still exists in both subject symptoms and response to therapeutic intervention.(2, 3) This inconsistent association between lung function and disease manifestations has led to increasing interest in image based methods for the diagnosis and classification of COPD.

The following is a review of the role of chest imaging in the detection and quantification of the structural and functional abnormalities of a lung affected by COPD. The history of this effort extends from the use of the Roentgenologic exam, through the evolution of Computed Tomography (CT) and Optical Coherence Tomography (OCT), into more functional imaging modalities such as contrast enhanced (both intravenous and inhaled) Magnetic Resonance Imaging (MRI). The primary focus of this review will be applications of CT scanning in clinical investigation with lesser mention of additional techniques because of their more limited ability to be performed in very large cohorts of subjects with COPD. Diagnostic Imaging and Spirometry Case Studies.

Chest X-Ray

Posteroanterior and lateral chest x-ray (CXR) is a standard part of the clinical evaluation of subjects with COPD. Such images are inexpensive, easily obtained, and involve minimal radiation exposure. Prior work by several groups has led to several proposed criteria for the detection of emphysema on CXR (Table 1, Figure 1). These include

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Figure 1

Posteroanterior and Lateral CXR of a normal healthy subject (panels A and B) and one with several emphysematous destruction of the lung parenchyma (Panels C and D).

  1. Increased radiolucency of the lung fields

  2. Flattening of the diaphragms

  3. Pruning of the peripheral vasculature

  4. Increased retrosternal airspace

  5. Widening of the intercostal spaces

  6. Narrowed and more vertical cardiac silhouette.

While the application of such criteria to CXR for the detection of emphysema has historically had mixed success in correlations to histopathologic examination (4, 5), recent investigation suggests that the semi-objective visual interpretation of chest radiographic images may have clinical utility. Diagnostic Imaging and Spirometry Case Studies. In 2008, Miniati and colleagues demonstrated that both experienced and inexperienced viewers could identify the presence of moderate and severe emphysema with over 90% sensitivity and specificity with minimal training.(6) While such an approach is not amenable to the detection of subtle changes on longitudinal examination or a regional assessment of disease, it does suggest that in the clinical setting, CXR may provide useful subjective phenotypic information in subjects with COPD.

Computed Tomography: Emphysema

The introduction of computed tomographic imaging has facilitated the in-vivo examination of the most fundamental aspect of lung structure, the secondary pulmonary lobule. In it can be found the juxtaposition of the pulmonary vessels, airways, lymphatics, and lobular septa that maintain normal lung function. It is also the site most recognizable on CT scan for its appearance in both health and disease.(7)

Emphysema is defined as the abnormal enlargement of the airspaces distal to the respiratory bronchioles resulting from the destruction of the septal walls.(8) On CT scan, this process results in visually apparent regions of low density tissue surrounded by more normal lung. The distribution of these regions of low attenuation and degree to which they involve the secondary pulmonary lobule can be characterized as centrilobular, panlobular, and paraseptal emphysema. As its name implies, centrilobular emphysema typically manifests as central destruction of the secondary pulmonary lobular parenchyma surrounding the centrilobular artery. In contrast, panlobular emphysema can be identified on CT scan as uniform destruction of the lobule. Finally, paraseptal emphysema is a form of panlobular emphysema localized primarily to the parenchyma adjacent to the pleural surface.(7) Examples of these conditions can be found in Figure 2. Diagnostic Imaging and Spirometry Case Studies.

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Figure 2

Examples of centrilobular (A), panlobular (B), and paraseptal emphysema (C). Images provided courtesy of the COPDGene® Study.

There are several methods for both the detection and quantification of emphysema on CT scan. These can be preliminarily divided into two categories, visual detection schemes and more objective techniques based upon lung density. Typically, subjective approaches to analysis such as visual interpretation involve either a global or regional assessment of the lung using an ordinal scoring system (i.e. 0–4) to reflect disease severity. Using visual interpretation schemes, multiple investigators have demonstrated a correlation to histopathology (9–12), lung function (13, 14), and even response to therapeutic intervention.(3) Limitations to these approaches are, however, their susceptibility to intra and inter-observer variability (15), sensitivity to the viewing conditions such as window width and level (16, 17), and potential insensitivity for the detection of disease progression in longitudinal studies.Diagnostic Imaging and Spirometry Case Studies.  Paradoxically, a potential strength to such analysis is that same ability of the user to be either consciously or unconsciously influenced by their visual perception of disease. Depending on the experience of the user, subtle patterns of disease may be observed that are not readily amenable to objective quantification.

In principle, a CT scanner is a densitometer where the brightness or attenuation of each pixel is a product of the density of the tissue it encompasses. These densities are expressed numerically in Hounsfield Units (HU) and generally range from −1000 HU (air) through 0 HU (water) to +1000 HU (bone) although the extremes can vary based upon CT scanner brand. Using this information, one can generate a histogram of the distribution of tissue densities in the lung, where each point is defined by the HU value of that pixel or voxel (3 dimensional pixel). Examples of these are shown in Figure 3. Multiple techniques for objectively identifying meaningful points on the CT lung histogram exist and include defining the mean lung density (18, 19), percentile points such as the Perc15 (HU threshold that delineates the lowest 15% of the histogram from the denser 85%) (20), and a fixed HU threshold such as −910 or −950 to identify the low attenuation regions of emphysema.(21, 22)

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Figure 3

Coronal images of a subject with minimal emphysema (top panels) and severe emphysema (bottom panels). For each subject, density histograms are presented for the upper (blue), middle (green), and lower (yellow) regions of lung divided by lung volume. Note the leftward shift in the density histograms of the subject with severe emphysema compared to the more normal smoker.

Since their inception over 30 years ago the afore mentioned methods of densitometric analysis have become standard for the detection and quantification of emphysema on CT scan and in the case of HU thresholding has been demonstrated on several occasions to offer correlates to the results of tissue necropsy.(21, 22) Through its application, investigators have found an objective tool for the prediction of surgical outcomes (23, 24) began to test drugs for their efficacy in the attenuation of disease progression (25), and have become increasingly aware of gender differences in the manifestations of smoking related lung disease.(26, 27) Despite these advances, lung densitometry is vulnerable to several influences including the lung volume at which the CT scan was obtained (28, 29) and the protocol used to acquire and reconstruct the images. Diagnostic Imaging and Spirometry Case Studies.(30) While the former may be addressed by a calculated volume correction (28), the latter still offers an unanswered challenge to discover one or several “correction factors” by which one set of images can be adjusted so that they are comparable to those obtained by a different brand of scanner which has generated similar but not exactly the same set of images.

Computed Tomography: Airway Disease

The site of expiratory airflow obstruction in smokers is believed to be the peripheral small airways.(31) While the size of these airways precludes their direct assessment on clinical CT scans, recent investigation has demonstrated that the morphology of the central cartilaginous airways reflect the distal remodeling process. In 2000, Nakano and colleagues demonstrated that in smokers, subjects with the greatest degree of mural thickening and lumenal occlusion of the apical segment of the right upper lobe tended to have the lowest FEV1 expressed as a percent of predicted (32) and a greater burden of distal small airway disease on histopathologic examination.(33) Further, the combination of CT measures of emphysema and densitometric measures of emphysema provided additive information when predicting lung function. Interestingly, there was no relationship between absolute airway wall thickness and lung function which alludes to the overall variability native airway morphology in this group. To address this issue investigators employed a measure called the Wall Area Percent (WA%) which is calculated as 100 times the airway wall area divided by the total bronchial cross sectional area.(32) This has become the standard CT based measure of airway disease in smokers.

There have since been several similar investigations of the correlation between CT measures of airway disease and lung function.(34–36) Among the most notable of these was work done by Hasegawa and colleagues who demonstrated that the quantitative assessment of the WA% of more distal airway generations (5th) provided stronger correlations to lung function than the proximal segmental airways (3rdgeneration) suggesting that a more robust biological signal could be detected in the most peripheral aspects of the bronchial tree.(34) This finding has been further extended by demonstrating that distal measures of WA% provided the strongest correlate to inhaled bronchodilator response. (37) Diagnostic Imaging and Spirometry Case Studies.

To this point, CT measures of airway disease have been defined as mural thickening with encroachment on the lumen. While useful for functional correlation, their relationship to another clinically significant occurrence, acute exacerbations of COPD, is currently undefined. In contrast, another radiographic form of airway disease, bronchiectasis, is increasingly being recognized for its association with elevated biomarkers of inflammation and the severity of respiratory events.(38)

Bronchiectasis is characterized radiographically as the abnormal dilation of the airway lumen with concomitant wall thickening.(39, 40) Its prevalence in the general population of smokers with COPD is unknown. In one of the largest reported CT based studies of smokers to date, Patel and colleagues found that approximately 2.5% of subjects had moderate to severe disease.(41) In contrast, Parr and colleagues found that almost 95% of their study cohort of subjects with AATD exhibited some bronchiectatic changes in their airways.(42) There are 2 notable differences to these studies. The first is that the prevalence estimate published by Parr and colleagues included subjects with even mild, regionally limited disease while those estimates reported by Patel and colleagues were based on severe disease that precluded quantitative airway analysis. The second is related to the unique pulmonary manifestations of smoking related lung disease in smokers with or without AATD. Further investigation is needed to determine the prevalence and clinical associations of bronchiectatic airway disease detected on CT scan in smokers.

Computed Tomography: Expiratory/Dynamic Imaging

While HRCT images provide detailed structural information, they are generally acquired in a single breath hold at full inflation. To fully exploit the potential of CT, investigators have begun to utilize static expiratory scans and in the case of more central airway disease such as tracheobronchomalacia, dynamic expiratory imaging.(43) One of the most striking findings on expiratory CT imaging in subjects with expiratory airflow obstruction is mosaic perfusion of the secondary pulmonary lobule (Figure 4). Regions of low attenuation represent relative oligemia due to local obstruction of either the vasculature or small airway which in the latter case results in focal gas trapping.(44) While recognized visually, little has been done to objectively quantify this distinct radiographic pattern.

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Figure 4

Examples of axial and coronal CT images obtained at full inflation (panels A and B) and at relaxed exhalation (panels C and D). Note the mosaic attenuation of the bottom 2 expiratory panels suggesting oligemia or gas trapping within the secondary pulmonary lobule. Diagnostic Imaging and Spirometry Case Studies.

Computed Tomography: Pulmonary Vascular Disease (PVD)

Clinicians and investigators have long recognized the significance of pulmonary vascular disease in subjects with COPD. In 1972, Burrows and colleagues performed right heart catheterization in 50 subjects with severe COPD revealing that 26% of them had resting mean pulmonary artery (Ppa) pressures ≥ 26 mmHg.(45) Subsequent investigations have estimated the prevalence of elevated pulmonary vascular pressures to be between 35% and 90%, the higher estimates reported in subjects with severe emphysema.(46, 47) In addition to the disabling dyspnea on exertion ascribed to pulmonary hypertension in subjects with COPD, the presence of pulmonary vascular disease in this cohort has been demonstrated to be a poor prognostic determinant of survival (45, 46, 48, 49) and is associated with increased utilization of healthcare resources.(50)

While CT scanning is a standard of care for the investigation of pulmonary thromboembolic disease, there has been little application of CT to conditions such as PVD associated with COPD. Recently, Matsuoka and colleagues conducted an investigation of the relationship between CT burdens of emphysema and PVD in smokers using a metric termed the CSA or cross sectional area.(51) In an axial image, the authors hypothesized that some of the apparent high density structures are small vessels captured orthogonal to their long axis. By examining the cross sectional area of those round structures, one may have an objective measure of the aggregate small pulmonary vasculature available for lung perfusion. Further, when constraining this analysis to those structures that are each less than 5 mm2 in cross sectional area, one can assess the CSA of the sub-sub segmental pulmonary vessels.

Using this metric of disease, Matsuoka and colleagues found that the CSA of those pulmonary vessels less than 5mm2 was inversely related to the CT burden of emphysema.(51) Not surprisingly, subjects with greater burdens of parenchymal destruction tended to have lower aggregate cross sectional area of the small pulmonary vasculature.Diagnostic Imaging and Spirometry Case Studies.  In a subsequent investigation, the same CSA measure was applied to a subset of subjects enrolled in the National Emphysema Treatment Trial (NETT) who underwent high resolution CT scanning and right heart catheterization for the invasive assessment of pulmonary artery pressures. In this cohort of subjects with severe emphysema, there was a marked inverse relationship between the vascular CSA and PA pressures while there was no evidence of a similar relationship between CT burdens of emphysema and PA pressures.(52) Further work needs to be done to replicate and validate these findings but CSA may prove to be a minimally invasive CT based assessment of pulmonary vascular disease in smokers.

Computed Tomography: Summary and Limitations

There are several technical as well as biologic limitations to the use of CT as a measure of lung disease in subjects with COPD. The first pertains to such considerations as the lack of manufacturer standardization of CT acquisition and reconstruction protocols across multiple brands and generations of scanners. Such systematic issues can bias data so that subjects at a given center may appear to have more or less emphysema for a given degree of tobacco smoke exposure or expiratory airflow obstruction. A second well documented limitation of quantitative CT scan analysis is the resolution imposed by clinical imaging protocols. Standard theory in image analysis states that structures smaller than 2 pixel widths in size cannot be resolved with accuracy. (53) Since the wall thicknesses of the 4th and 5th generation airways tend to fall in this range, consideration must be given to the accuracy of such measures prior to clinical application despite their providing a more robust biologic signal.

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Additional seemingly simple biologic considerations that must be acknowledged include the level of inspiratory effort a subject exerts to achieve a full inflation scan. The lung (and in turn the airways) expand isotropically with inflation (54) so that for a given subject, the greater the degree of inflation, the greater the apparent burden of emphysema (by a corresponding reduction in lung density) and potentially diminished CT burden of airway disease (by dilating the airway lumen used to calculate cross-sectional measures of WA%). While the impact of such variability is recognized, and efforts are being made to adjust CT measures of emphysema for inspiratory effort (55), thus far there are no similar adjustments for CT measures of airway disease. Diagnostic Imaging and Spirometry Case Studies.

Finally, while CT imaging is a relatively safe, non-invasive tool that can be used on a large scale for genetic and epidemiologic studies, as a modality, it is limited in its ability to asses such things as the detailed mural remodeling process found in airway disease or the regional function of seemingly emphysematous tissue. In addition, general tendencies for subjects with thicker walls and smaller airway lumens to have greater expiratory airflow obstruction have been reproduced, but a single reported value of WA% at a single site in a single subject has little clinical meaning. Because of this, there is great interest in additional imaging modalities such as optical coherence tomography (OCT) and magnetic resonance imaging (MR) that may provide more detailed structural information and possibly insight into tissue function without the potential risks of ionizing radiation exposure inherent in CT.(56) Diagnostic Imaging and Spirometry Case Studies.