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28
CASE 28
History
A 29-year-old male presented with intermittent pain in both arms. Images
28band 28c were taken just 1 minute apart – what has happened between them?
29b
CASE 29
History
A 65-year-old male presented with progressively worsening shortness of breath.
29a
a
ANSWER 29
Observations (29a, 29b)
Two axial CT images of the chest show features of cardiomegaly, bilateral pleural effusions and patchy ‘ground glass’ opacity with smooth interlobular septal thickening. This combination of imaging findings would fit with a diagnosis of pulmonary oedema.
Diagnosis
Pulmonary oedema due to heart failure.
Differential diagnosis
For ‘ground glass’ opacity: • Pulmonary oedema. • Infection.
• Haemorrhage.
• Interstitial pneumonias. • Extrinsic allergic alveolitis. • Alveolar proteinosis. • Sarcoidosis.
• Focal areas of ‘ground glass’ – alveolar cell carcinoma/lymphoma.
For smooth interlobular septal thickening: • Pulmonary oedema.
• Alveolar proteinosis. • Pulmonary fibrosis.
For nodular interlobular septal thickening: • Lymphangitis carcinomatosa.
• Sarcoidosis.
Discussion
Cardiac failure is a diagnosis usually made clinically and confirmed with CXR. The following findings tend to progress in sequence as the condition deteriorates and pulmonary venous pressure increases further:
• Upper zone vascular predominance.
• Interstitial oedema with peripheral reticulations and Kerley B lines.
• Alveolar oedema with a perihilar predominance (‘bat’s wing’ appearance).
The following features provide supplementary evidence to suggest the diagnosis:
• Cardiomegaly with cardiothoracic ratio >50%. • Pleural effusion.
ANSWER 28
Observations (28a, b, c)
Selected images from an arch aortogram. The first image (28a) is a pre-contrast image which demonstrates bilateral cervical ribs. The second image (28b) shows a pigtail catheter in the arch with contrast injected and normal appearance of the aortic arch and the proximal main branches. The third image (28c) shows bilateral occlusion of the subclavian arteries at the level of the thoracic outlet. Given the presence of cervical ribs, it is suspected that the second image was acquired with the arms down, and the third image with the arms elevated.
The patient has thoracic outlet syndrome.
Diagnosis
Thoracic outlet syndrome secondary to bilateral cervical ribs.
Differential diagnosis
Of causes of thoracic outlet syndrome:
• Congenital – cervical rib, fibrous band or abnormal 1st rib.
• Acquired – first rib exostosis or fracture, body habitus.
Discussion
Thoracic outlet syndrome is a clinical syndrome caused by nerve, artery or vein compression in the root of the neck upon elevation of the arms. The vast majority of symptoms arise due to nerve compression and vascular symptoms are found in as few as 2% of symptomatic patients. The subclavian artery and/or vein are transiently occluded with arm movement, but more permanent vascular problems can arise due to the repeated trauma of compression – focal stenosis, poststenotic dilatation and aneurysm formation. The result of this is upper limb ischaemic symptoms with pain, a cold limb and Raynaud’s phenomenon. Further complications of poststenotic thrombus formation and subsequent embolism can occur.
Practical tips
Cervical ribs occur in ~3–4% of the population but are only symptomatic in 10% of cases.
Further management
• US is useful as a dynamic test for assessing arterial Doppler signal with the arm in a neutral and elevated position.
• CT/MRI can be useful in identifying the cause of compression if not apparent on plain radiography.
Answer 29
Chest Imaging
Case 30
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These same findings are visible on CT. Alveolar fluid often presents as ‘ground glass’ opacity, which is an increased haziness/attenuation in the lung – and which can be patchy in distribution. ‘Ground glass’ opacity is a relatively nonspecific imaging finding due to many conditions that cause an overall increase in density within the segment of lung displayed as a pixel on the CT image. There is a long differential diagnosis including any cause of alveolar fluid/consolidation.
Practical tips
A combination of cardiomegaly, pleural effusion and airspace opacity suggests cardiac failure with pulmonary oedema.
Further management
Medical management with CXR radiological follow-up as appropriate.
CASE 30
History
A 65-year-old male was referred for a cardiac MRI to assess cardiac viability.
30a
ANSWER 30
Observations (30a, 30b)
The first image (30a) is a short axis scan through the left ventricle during the first pass of contrast. There is no contrast enhancement of the thinned left ventricular septal and anterior walls. The visualized posterior, lateral and inferior walls show normal enhancement and are of normal thickness. The second image (30b) is a delayed four chamber view showing delayed, prolonged enhancement of the septal, apical and anterolateral wall of the left ventricle. These appearances are of an extensive left ventricular infarct with no evidence that involved areas are viable.
Diagnosis
Left ventricular infarct involving the septal/apical/ anterolateral walls.
Discussion
Cardiac MRI has an expanding role and current uses include assessment of:
• Cardiac viability prior to revascularization. • Cardiac congenital heart defect.
• Cardiac tumours. • Pericardial disease. • Cardiomyopathies.
Assessing cardiac viability post myocardial infarction is important since revascularization of live tissue reduces morbidity and mortality. Previously cardiac perfusion was assessed by cardiac nuclear medicine (MIBG – meta- iodobenzylguanidine [scintiscan]) stress testing but there is now an increased role for cardiac MRI.
Short axis cine images are acquired at first pass of a bolus injection of gadolinium to determine perfusion. Infarcted myocardium shows no enhancement on first-pass imaging (as demonstrated in this case). In addition, first- pass imaging can show:
• Whether the infarct is transmural or subendocardial. • Degree of hypo/akinesia.
Delayed enhancement sequences at approximately 5 min
show enhancement in infarcted tissue since clearance of contrast from fibrotic tissue is slower than from normal myocardium.
If there is any uncertainty regarding differentiation of ischaemic from infarcted myocardium then cardiac MRI stress testing is performed with first-pass images acquired at stress with adenosine and then repeated after 20 min at rest. Areas of hypoenhancement at stress that show recovery at rest represent areas of ischaemia rather than infarction.
Practical tips
Cardiac MRI is a dynamic test that requires assessment of cine images to make a subjective and objective assessment of left ventricular function (ejection fraction).
Further management
Coronary artery atherosclerotic disease is characterized using coronary angiography or coronary artery CT. Patients with ischaemic but viable myocardium may be suitable for revascularization with angioplasty or bypass grafting.
30b Transmural delayed gadolinium enhancement.