Pulmonic Valvular Stenosis

Chest radiograph reveals dilatation of the main pulmonary artery with relatively normal-sized right and left pulmonary arteries. The aorta is left sided.

Facts: Pulmonary Valvular Stenosis

• Common congenital heart defects, approximately 10% of all cases
• Classified as subvalvular, valvular and supravalvular stenosis (based on level of obstruction) and as mild, moderate and severe (based on pressure gradient across stenosis). It can occur in branch pulmonary arteries as well
• May occur in isolation (as in our case) or be associated with other complex congenital heart defects
• In severe cases, physical and ECG findings of right axis deviation, right ventricular hypertrophy would be apparent

Imaging Findings

• Cardiac ultrasound: obstruction at right ventricular outflow tract (RVOT), pulmonary valve (PV), main pulmonary artery, right and left pulmonary arteries, abnormal pulmonary valve annulus, abnormal pressure gradients across RVOT, PV and pulmonary arteries
• Radiography: enlargement of the main pulmonary artery, right ventricular hypertrophy. Radiographic differential diagnoses are pulmonary hypertension, idiopathic dilatation of the pulmonary trunk

Our case - pulmonary valvular stenosis in a young woman who had the diagnosis since birth and had undergone valvulotomy.

References

1. Heiden K. Congenital heart defects, simplified. 2009

2. Castaner E, Gallardo X, Rimola F, et al. Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview. Radiographics 2006;26:349-371.

Giant Bulla Vs. Pneumothorax

Chest radiograph shows a large lucent area in the right upper lobe with compression of the remaining lung parenchyma. In a patient with acute symptoms and no previous radiograph for comparison, this may raise a diagnostic dilemma whether it represents localized pneumothorax or just a giant bulla.
Coronal-reformatted CT image confirms the absence of pneumothorax in this case. Several bullae are clearly visualized.

Facts: Bulla, Giant Bulla

• Air-filled space in the lung parenchyma due to destruction of alveolar tissue, distal to terminal bronchiole
• Larger than 2 cm in distended state
• Bullae + emphysema = bullous emphysema (can be congenital or complication of COPD)
• Giant bulla = bulla larger than one third of the hemithorax size and compression of adjacent lung parenchyma

Distinguish Giant Bulla from Pneumothorax

• Important for treatment plan (bulla - no tube thoracostomy; pneumothorax - may need tube thoracostomy if large or symptomatic)
• Differentiation can be difficult on conventional radiography; they can coexist
• Helpful signs for pneumothorax: visible visceral pleural line
• Expiratory chest radiograph may help delineating a visceral pleural line of pneumothorax
• CT scan is the most accurate mean to differentiate the two diagnoses
• "Double wall" sign described in cases with ruptured bulla causing pneumothorax (air outlining both sides of the bulla wall parallel to the chest wall)

Lesson: Don't be shy to ask for a CT scan in this scenario. It is better to "do right" than "be right". The treatment is very different, and remember that the two diagnoses can coexist.

Reference:

Waseem M, Jones J, Brutus S, et al. Giant bulla mimicking pneumothorax. J Emerg Med 2005;29:155-158.

Intervertebral Disc Calcification

Sagittal-reformatted CT image of the lower thoracic spine shows a central disc calcification. Several levels of endplate changes are noted as well.

Commonly Found in Elderly

• Found in 80% of elderly cadavers in a large study
• Mostly located in the periphery of the disc (annulus fibrosus), followed by central and diffuse
• Mostly in lower thoracic spine, followed by midthoracic and lumbar spine
• Increase in prevalence with increasing age

Differential Diagnosis

• Degenerative disc
• Postoperative, post-traumatic
• Arthritis: ankylosing spondylitis, CPPD, gout
• Metabolic disease: ochronosis, hemochromatosis, hypervitaminosis D

Reference:

Chanchairujira K, Chung CB, Kim JY, et al. Intervertebral disk calcification of the spine in an elderly population: radiographic prevalence, location, and distribution and correlation with spinal degeneration. Radiology 2004;230:499-503.

Thyroglossal Duct Cyst

Sagittal CT image of the neck shows a cystic mass (arrow) in the midline anterior to the hyoid bone (arrowhead) in a young male patient.

Facts:

• Cystic lesion in the midline of the anterior neck near the hyoid bone
• Common, accounted for 70% of all congenital neck mass
• Usually is mobile, midline or slightly off midline
• Can be anywhere along the route from foramen cecum to the lower neck (a path the thyroid gland descends to reach the anterior trachea). But most are below the level of hyoid bone
• Treatment involves removal of the entire duct, part of the hyoid bone and tissue at the base of tongue

Differential Diagnosis

• Dermoid cyst
• Liquefied submental or anterior cervical lymph node

Reference:

Seibert J, James C. Pediatric Radiology Casebase, 1997.

Cavernoma

Axial CT image shows a small well-defined hyperdense lesion (arrow) in the gray-white matter junction of the left posterior parietal lobe without evidence of mass effect or surrounding edema.

Axial T2W MR image shows the lesion predominantly high signal intensity with a complete ring of dark T2 signal, suggesting the presence of hemosiderin.

Facts: Cavernoma

• Low-flow vascular anomaly of the brain
• Endothelium-lined blood cavities without muscular or adventitial layers. No brain tissues present between these blood cavities
• May be sporadic, related to prior radiation, or hereditary
• Patients commonly present with seizures due to internal bleeding
• Annual bleeding rate between 0.25 to 0.7% per year
• On follow up, most cavernomas increase in size due to osmotic changes
• 80% are supratentorium, and size between 1-2 cm

Imaging

• Appearance depends on amount of internal thrombosis, hemorrhage and calcification
• MRI is the modality of choice because it can show various stages of bleeding in the lesion, which is characteristic for cavernoma
• If presents with acute hemorrhage, CT appearance will be similar to intracerebral hemorrhage of other causes. MRI in acute phase may provide a clue to the diagnosis of cavernoma if it shows various stages of bleeding in particular the presence of hemosiderin
• If presents incidentally, cavernoma appears as a hyperdense mass without causing mass effect on CT. If calcified, it will be only partially calcified. On MRI, it shows a complete ring of dark T2 signal due to the presence of hemosiderin (this effect is best seen on GRE T2* sequence)

Reference:

Kuker W and Forsting M. Cavernomas and Capillary Telangiectasias. In: Baert AL, Knauth M, Sartor K. Intracranial Vascular Malformations and Aneurysms, 2nd revised edition, 2008