Spot Diagnosis

Dental cyst

This 30-years old patient had pain in the right lower jaw. He had been treated earlier for caries. An OPG showed an osteolytic lesion and the patient came for a dental CT, which showed a well-defined, odontogenic lesion, with its epicentre in relation to the root of the first molar tooth, but extending from the second premolar to the second molar (Figs. 1-4).

This appearance is highly suggestive of a dental cyst, also called a radicular or apical or periapical cyst. It occurs as a result of root infection.

Severe pancreatitis - abscess drainage

In patients with severe pancreatitis, one of the complications that often occurs is abscess formation. Invariably, it proceeds from infection of an acute fluid collection.

Once there is a frank abscess, an image-guided drainage can be easily performed, as in this case, where the drainage catheter is seen in the anterior abscess.

Steroid injection into a simple bone cyst

This 11-years old girl had left hip pain. The plain radiograph showed a mildly expansile osteolytic lesion with a narrow zone of transition in the distal neck (Fig. 1). A simple bone cyst was suspected and the CT (Fig. 2) and MRI (Figs. 3-5) confirmed this possibility.

In view of the age and location, the treating doctor decided to treat the patient conservatively and sent her for a CT-guided steroid injection. This was performed with CT fluroscopy control and after introducing a needle into the lesion (Fig. 6), a mixture of methylprednisolone and intravenous contrast was injected (Figs. 7, 8). Queried after a week, the patient confirmed relief from pain.

Head injuries Lecture - Slides 46-50

Emphysematous pyelonephritis

Sometimes, patients with acute focal bacterial nephritis, progress to frank abscess formation and on occasion, especially with diabetics, the infection involves gas-forming organisms, leading to the entity emphysematous pyelonephritis.

The diagnosis on CT is relatively easy, with the presence of a focal area of necrosis and altered density with air, which may extend into the peri-renal space (Figs. 1-3)

Air trapping

Plain Radiograph:
The retention of excess gas in all or part o fthe lung at any stage of expiration; to be used only when excess air is demonstrated by a dynamic study, such as inspiration/expiration films or fluoroscopy. Not to be used for overinflation

CT:
Decreased attenuation of pulmonary parenchyma, especially manifest as less than normal increase in attenuation during expiration. To be differentiated from decreased attenuation of hypoperfusion secondary to locally increased pulmonary arterial resistance.

The inspiratory and expiratory images shown below demonstrate air-trapping in the left lower lobe secondary to obliterative/constrictive bronchiolitis

Polyostotic fibrous dysplasia

This young patient has multiple lesions involving the maxilla and mandible (Figs. 1-5), all except one showing bone formation and expansion. The mandibular condylar lesion (Fig. 4) shows an osteolytic lesion, which is also known in patients with fibrous dyplasia.

Polyostotic fibrous dysplasia often occur only in the cranio-facial skeleton and may not involve the rest of the skeleton. It may be associated with other metabolic abnormalities, unlike monostotic fibrous dysplasia.

Pancreatitis - aspiration of fluid collections

In the absence of air, it is not possible to deduce whether a fluid collection in infected or not. If there is a strong clinical suspicion of infection, and if there is no air or air-fluid level, then a CT or USG-guided aspiration of one or more of the collections is suggested, for this purpose.

In this patient, there are multiple acute fluid collections (Figs. 1, 2). Infection was suspected and though frank pus was not aspirated (Fig. 3), the aspirate grew gram negative bacteria and the patient was put on appropriate antibiotics and improved.

Scapular focal lesion - biopsy

This 26-years old lady had a compression fracture of the C5 vertebral body. She came for a biopsy, but there was no access route. A bone scan was advised, which revealed a lesion in the scapula. This was biopsied (Figs. 1, 2), by introducing a bone cannula inside, through which an 18G Quick-Core gun was used. It revealed metastatic squamous cel carcinoma.

A CT scan of the chest subsequently revealed a mass in the right lower lobe.

Head injuries Lecture - Slides 44, 45