Tracheal Bronchus

Axial and coronal-reformatted CT images in a patient with tuberculosis of the right upper lobe (stars) show a tracheal bronchus (arrows) arising from the right lateral wall of the trachea, within 2 cm of the carina. Note a normal-appearing right upper lobe bronchus (arrowhead). 

Facts

• Abnormal bronchus arising directly from the lateral wall of the trachea (on either side, but right side is more common), supplying the upper lobes
• 0.1% - 2% incidence
• Most cases are found incidentally on bronchoscopy or CT
• Associated with other anomalies such as ribs, vertebrae

Types

• Two types: displaced, or supernumerary
• "Displaced" type = RUL bronchus or any of its segmental bronchus in cephalad location than normal. If the entire RUL bronchus arises from tracheal wall, it is called "bronchus suis"
• "Supernumerary" type = normal RUL bronchus and its segmental bronchi but there is extra bronchus arising directly off the lateral wall of the trachea

Clinical implications

• In children, it is associated with recurrent infections, stridor, respiratory distress and thoracic masses
• In adults, it can complicate endotracheal intubation (occlusion or accidental intubation of a tracheal bronchus can cause atelectasis)

Our case: supernumerary bronchus arising from the right lateral wall of the trachea. The patient presented with TB of the right upper lobe. 

Reference:

Aoun NY, et al. Tracheal bronchus. Respir Care 2004;49:1056-8.

Gastric Emptying Scintigraphy: SNM Recommendation

Facts: Gastric Emptying Scintigraphy

• Performed to evaluate patients with symptoms suggesting alteration of gastric emptying or motility
• Provide physiologic, noninvasive, quantitative measurement of solid or liquid gastric emptying
• Used to diagnose delayed gastric emptying (ie, gastroparesis) or rapid emptying (dumping syndrome)

Factors affecting gastric emptying (potentially creating false-positive or false-negative tests)

• Medications: prokinetics (shorten gastric emptying), narcotic analgesics (prolong gastric emptying)
• Tobacco smoking (prolong gastric emptying)
• Hyperglycemia (prolong gastric emptying)
• Premenopausal status (prolong gastric emptying)

Standards for performing GES as recommended by Society of Nuclear Medicine (SNM)

• Full recommendation paper (link) provides recommended timing of imaging, composition of meal, glycemic control, monitoring of symptoms and assessment of severity
• Low-fat, egg white meal
• Imaging at a minimum at 0,1,2 and 4 hours after radiolabeled meal ingestion

Tuberous Sclerosis Complex

Axial T1W MR image of a 5-year-old girl demonstrates several T1-hyperintense subependymal nodules arrows).

Coronal FLAIR MR image shows multiple cortical tubers and subcortical white matter hyperintensities (asterisks).

Facts

• Autosomal dominant disorder due to abnormality of TSC1 and TSC2 genes
• Most frequent clinical manifestations are neurologic (myoclonic seizures in early childhood, psychiatric symptoms, retinal hamartomas) and skin (adenomas of sebaceous glands)

Diagnostic Criteria by Tuberous Sclerosis Complex Consensus Conference (Maryland 1998)

Major features

• Facial angiofibromas or forehead plaque
• Nontraumatic ungual or periungual fibroma
• Hypomelanotic macules (more than 3)
• Shagreen patch (connective tissue nevus)
• Cortical tuber
• Subependymal nodule
• Subependymal giant cell astrocytoma
• Multiple retinal nodular hamartomas
• Cardiac rhabdomyoma, single or multiple
• Lymphangiomyomatosis (LAM)
• Renal angiomyolipoma (AML)

Minor features

• Multiple randomly distributed pits in dental enamel
• Hamartomatous rectal polyps
• Bone cysts
• Cerebral white matter "migration tracts"
• Gingival fibromas
• Nonrenal hamartoma
• Retinal achromic patch
• Confetti skin lesions
• Multiple renal cysts

Definite TSC: Either 2 major, or 1 major + 2 minor features

Probable TSC: One major + one minor feature

Possible TSC: Either 1 major, or 2 or more minor features

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Imaging findings are highlighted in red.

When both LAM and renal AML are present, other features should be present as well before definite diagnosis is made. 

Reference:

Roach ES, Sparagana SP. Diagnosis of tuberous sclerosis complex. J Child Neurol 2004;19:643-649. Fulltext