RADIOLOGY MCQ -----CNS FUNGAL INFECTION

Q.All are  true regarding fungal infection of CNS except

a. Cryptococcus, Histoplasma result in leptomeningitis more  frequently than  parenchymal lesions due to large size

b. the candidiasis abscess appears as  “target appearance” on T2W image

c. “gelatinous pseudocysts” in CNS cryptococcosisis is  noted primarily in the basal ganglia and midbrain 

d. an acute hemorrhagic infarction is seen in aspergillosis

e.  the trehalose resonance at 5.19 ppm is  noted  in cryptococcoma

ANS.---a

Fungi that grow in infected tissues as yeast cells (Cryptococcus, Histoplasma) are spread hematogenously and, due to their small size, reach the meningeal microcirculation, penetrate the vessel walls, and result in acute or chronic leptomeningitis. Less frequently, parenchymal lesions such as granulomas and/or abscesses are encountered.

Fungi that grow in infected tissues as hyphae (Aspergillus, Mucor) or pseudohyphae (Candida) tend to involve the parenchyma rather than the meninges because their larger size limits access to meningeal microcirculation

C. neoformans is the most common fungus to involve the CNS, and cryptococcosis is the most common fungus infection in AIDS patients

Cryptococcosis primarily manifests as meningitis, most pronounced in the cranial base.

Four patterns of cryptococcal CNS infection may be encountered: parenchymal mass lesions, also known as cryptococcomas; dilated Virchow-Robin spaces (“gelatinous pseudocysts”); parenchymal/leptomeningeal nodules; and a mixed pattern.Virchow-Robin spaces of perforating arteries become distended with fungus and mucoid material, primarily in the basal ganglia and midbrainGelatinous pseudocysts do not display significant enhancement. The lesions may have mild mass effect, but there is no surrounding edema.The gelatinous pseudocysts are isointense to CSF on MR imaging, although they can often be slightly hyperintense on T1-weighted images. Primarily located in the midbrain and basal ganglia, they can be bilateral and are often symmetric . These pseudocysts do not enhance with gadolinium because the blood–brain barrier is not disrupted, and they are rarely associated with edema.

When there is hematogenous spread, usually from a pulmonary focus, Aspergillus hyphae lodge in cerebral vessels, cause occlusion, and grow through the vessel walls, producing infectious vasculopathy. Thus, an acute hemorrhagic infarction occurs at the beginning of the processes. Later, this converts to a septic infarction with associated cerebritis and abscess formation, usually in the distribution of the anterior and middle cerebral arteries . The basal ganglia and the thalami are characteristically involved in aspergillosis, as well as the corpus callosum and the brain stem. Involvement of the perforating arteries illustrates the invasive character of Aspergillus within the walls of the main cerebral arteries.

MR spectroscopy reveals decreased NAA and markedly elevated lactate levels and the presence of succinate and acetate in CNS mucormycosis.

HUEBNER ENDATERITIS

480.All are true regarding neurosyphilis except

a. Vascular neurosyphilis usually appears around 5 to 10 years after primary infection

b. Heubner endarteritis  is the most common form of syphilitic arteritis, affecting small arteries

c. Syphilitic gummas  occur 3 to 10 years after infection

d. General paresis usually presents 10 to 20 years after the initial infection

e. MR imaging shows hyperintense signal on T2-weighted images and contrast enhancement in the posterior spinal cord and dorsal nerve roots.

480.---b

Two types of vascular involvement have been described in neurosyphilis—Heubner endarteritis and Nissl-Alzheimer endarteritis.

The Heubner type is the most common form of syphilitic arteritis, affecting large and medium-sized arteries. Pathophysiologically, there is fibroblastic proliferation of the intima, thinning of the media, and adventitial fibrous and inflammatory changes, resulting in an irregular luminal narrowing and ectasia.

Less frequently, the Nissl-Alzheimer type of arteritis is present, primarily involving small vessels in which a luminal narrowing occurs as a consequence of intense proliferation of endothelial and adventitial cells. Both types of arteritis may lead to vascular occlusion. Moreover, syphilis can be associated with a venous occlusive inflammation.

Tabes dorsalis is a myelopathy associated with atrophic, degenerated, and demyelinated dorsal nerve roots and posterior spinal columns and appears 10 to 20 years after the initial infection . A triad of symptoms (lightning pains, dysuria, and ataxia) and a triad of signs (Argyll-Robertson pupil, areflexia, loss of proprioception) are the characteristics of this disorder . The Argyll-Robertson pupil, seen in both tabes dorsalis and general paresis, is a small, irregular pupil that accommodates but does not react to light.

MR imaging typically demonstrates brain  atrophy associated with hyperintense signal intensity on T2-weighted images and contrast enhancement in the posterior spinal cord and dorsal nerve roots.

SARTESCHI AND DUBIN CLASSIFICATION

The blood vessels of the pampiniform plexus are usually no more than 1.5 mm in diameter.

CDUS is currently considered the gold-standard technique for varicocele assessment because it allows accurate diagnosis (with a sensitivity and a specificity close to 100%)


When a patient with a varicocele is examined at rest, multiple elongated, tortuous anechoic structures are seen above, around, or beneath the testicle 
 The vessel caliber thresholds used by different authors to define varicocele vary from 2 to 3 mm 

Under baseline conditions, blood flow may be too slow to be detected by CDUS, but during the Valsalva maneuver the varicocele enlarges and flow reversal becomes evident. Some authors suggest that varicoceles should also be assessed while the patient is standing.

Sarteschi classification 

1	Reflux in vessels in the inguinal channel is detected only during the Valsalva maneuver, while scrotal varicosity is not evident in the standard US study
2	Small posterior varicosities that extend to the superior pole of the testis. Their diameters increase and venous reflux is seen in the supratesticular region only during the Valsalva maneuver.
3	Vessels appear enlarged at the inferior pole of the testis when the patient is evaluated in a standing position; no enlargement is detected if the patient is examined in a supine position. Reflux observed only under during the Valsalva maneuver.
4	Vessels appear enlarged even when the patient is studied in a supine position; the dilatation is more marked in the upright position and during the Valsalva maneuver. Testicular hypotrophy is common at this stage.
5	Venous ectasia is evident even in the prone decubitus and supine positions. Reflux is observed at rest and does not increase during the Valsalva maneuver.

Dubin classification.

Grade	Features
0	Moderate, transient venous reflux during the Valsalva maneuver (physiologic findings)
1	Persistent venous reflux that ends before the Valsalva maneuver is completed
2	Persistent venous reflux throughout the entire Valsalva maneuver
3	Venous reflux that is present under basal conditions and does not change during the Valsalva maneuver

igure 1

Varicocele (A) with reflux in the vessels of the inguinal canal seen only during the Valsalva maneuver and (B) absence of varicosity on the standard US examination (A) (grade 1).

Varicocele with small varicosities (A) that exhibit reflux only during the Valsalva maneuver (B,C) (grade 2).

Figure 3

Varicocele with enlarged veins (A) whose calibers increase during the Valsalva maneuver (B) (grade 3).

Figure 4

Varicocele with enlarged veins (A) whose calibers do not increase during the Valsalva maneuver (B) (grade 4).

ref ---J Ultrasound. 2011 Dec; 14(4): 199–204.