Answer for BIR CoW 11 Oct 2020
TUBERCULAR ABSCESS
Findings
Multiple coalescent lesions with T2 hyperintense center and peripheral hypointense rim noted in left parietal lobe with moderate surrounding vasogenic edema. Center of the lesion shows diffusion restriction. Lesion causes mass effect with compression of left lateral ventricle with midline shift of 7mm to the right. Magnetization Transfer images showed low MTR(17.8) in rim. On contrast administration, lesion shows peripheral ring enhancement, with adjacent meningeal enhancement MR spectroscopy of lesion revealed large lipid lactate peak. ASL Perfusion revealed no significantly increased cerebral blood flow.
Discussion
The MRI Features were suggestive of Tubercular abscess. The morphology and MR Spectroscopy features are not suggestive of Pyogenic Abscess which is discrete and not multiloculated rim enhancing like Tubercular abscess and MRS shows presence of cytosolic aminoacids . Unlike Tubercular granulomas with central caseation , abscesses are larger with thin walls . MT imaging is used to differentiate tuberculous from pyogenic abscesses. The rim of tuberculous abscesses (19.89 +\- 1.55) show lower MTR (MTR) values compared with pyogenic abscesses (24.81 +\- 0.03). The low MTR is due to high lipid content of tuberculous bacilli. CNS tuberculosis infection is caused by acid-fast bacillus Mycobacterium tuberculosis. It usually results from hematogenous spread. The different forms of CNS tuberculosis including meningitis, cerebritis, cerebral abscesses, tuberculomas, miliary tuberculosis, and spinal or calvarial involvement. Tuberculous abscess is a rare manifestation of CNS TB. As it usually does not contain pus with neutrophils, most TB"abscesses" are more correctly called pseudoabscesses. Tuberculous abscess consists of vascularised granulation tisssue with abundant viable tubercle bacilli, central liquefied necrotic debris and macrophages. CNS TB occurs in all age group. Patient will present with fever, headache, seizures, coma, signs of raised ICT. CSF analysis may show low glucose, elevated protein, lymphocytic pleocytosis. CSF smear, culture and PCR gives definite diagnosis. Imaging findings in Tuberculomas depend on the stage of tuberculoma, whether it is noncaseating or caseating with solid or liquid cente . Solid Non caseating Tuberculoma appear hypointense on both T1W and T2W images. They show homogeneous enhancement on post contrast scans. A caseating granuloma with solid centre is isointense to hypointense on both T1W and T2W images and shows isointense to hyperintense rim on T2W images. It shows rim enhancement on postcontrast images A caseating granuloma with liquefied centre becomes hypodense on CT and hyperintense on T2W images with a peripheral hypointense rim and shows peripheral enhancement. Liquid caseating lesions show restricted diffusion, whereas solid caseating lesions do not reveal restriction of diffusion. Hence T2 hypointense solid caseating lesions can be differentiated from lymphoma and medulloblastoma, which show restricted diffusion The cellular components of the noncaseating tuberculomas appear brighter on MT T1W imaging. This feature is specific for the disease and thus helps in differentiating these lesions from metastases, lymphomas, and other infective granulomas. Presence of tuberculomas at the corticomedullary junction suggests the hematogenous spread of infection, because there is narrowing of the arterioles at the gray/white matter junction. Chronic sequelae of Tubercular Abscess are hydrocephalus, calcifications, atrophy, syringobulbia, syringomyelia. Common complications of CNS TB include hydrocephalus,stroke. The majority of survivors have long-term morbidity with seizures, mental retardation, neurologic deficits, and even paralysis. Differential diagnosis include pyogenic abscess and neoplasm. Management includes multidrug therapy with Isoniazid, rifampin, pyrazinamide, ethambutol or streptomycin.Despite therapy, lesions may develop or increase. Hydrocephalus typically requires CSF diversion.
References:
1.Osborn’s Brain: Imaging, Pathology and Anatomy.
2.Central Nervous System Tuberculosis: An Imaging-Focused Review of a Reemerging Disease-Morteza Sanei Taheri, Mohammad Ali Karimi, Hamidreza Haghighatkhah,Ramin Pourghorban, Mohammad Samadian,andHosein Delavar Kasmaei.(Hindawi)
3.Central Nervous System Tuberculosis Deepak Patkar MD ,, Jayant Narang MD,, Rama Yanamandala MD,, Malini Lawande MD and Gaurang V. Shah MD Neuroimaging Clinics of North America, 2012-11-01, Volume 22, Issue 4, Pages 677-705,
Findings
Multiple coalescent lesions with T2 hyperintense center and peripheral hypointense rim noted in left parietal lobe with moderate surrounding vasogenic edema. Center of the lesion shows diffusion restriction. Lesion causes mass effect with compression of left lateral ventricle with midline shift of 7mm to the right. Magnetization Transfer images showed low MTR(17.8) in rim. On contrast administration, lesion shows peripheral ring enhancement, with adjacent meningeal enhancement MR spectroscopy of lesion revealed large lipid lactate peak. ASL Perfusion revealed no significantly increased cerebral blood flow.
Discussion
The MRI Features were suggestive of Tubercular abscess. The morphology and MR Spectroscopy features are not suggestive of Pyogenic Abscess which is discrete and not multiloculated rim enhancing like Tubercular abscess and MRS shows presence of cytosolic aminoacids . Unlike Tubercular granulomas with central caseation , abscesses are larger with thin walls . MT imaging is used to differentiate tuberculous from pyogenic abscesses. The rim of tuberculous abscesses (19.89 +\- 1.55) show lower MTR (MTR) values compared with pyogenic abscesses (24.81 +\- 0.03). The low MTR is due to high lipid content of tuberculous bacilli. CNS tuberculosis infection is caused by acid-fast bacillus Mycobacterium tuberculosis. It usually results from hematogenous spread. The different forms of CNS tuberculosis including meningitis, cerebritis, cerebral abscesses, tuberculomas, miliary tuberculosis, and spinal or calvarial involvement. Tuberculous abscess is a rare manifestation of CNS TB. As it usually does not contain pus with neutrophils, most TB"abscesses" are more correctly called pseudoabscesses. Tuberculous abscess consists of vascularised granulation tisssue with abundant viable tubercle bacilli, central liquefied necrotic debris and macrophages. CNS TB occurs in all age group. Patient will present with fever, headache, seizures, coma, signs of raised ICT. CSF analysis may show low glucose, elevated protein, lymphocytic pleocytosis. CSF smear, culture and PCR gives definite diagnosis. Imaging findings in Tuberculomas depend on the stage of tuberculoma, whether it is noncaseating or caseating with solid or liquid cente . Solid Non caseating Tuberculoma appear hypointense on both T1W and T2W images. They show homogeneous enhancement on post contrast scans. A caseating granuloma with solid centre is isointense to hypointense on both T1W and T2W images and shows isointense to hyperintense rim on T2W images. It shows rim enhancement on postcontrast images A caseating granuloma with liquefied centre becomes hypodense on CT and hyperintense on T2W images with a peripheral hypointense rim and shows peripheral enhancement. Liquid caseating lesions show restricted diffusion, whereas solid caseating lesions do not reveal restriction of diffusion. Hence T2 hypointense solid caseating lesions can be differentiated from lymphoma and medulloblastoma, which show restricted diffusion The cellular components of the noncaseating tuberculomas appear brighter on MT T1W imaging. This feature is specific for the disease and thus helps in differentiating these lesions from metastases, lymphomas, and other infective granulomas. Presence of tuberculomas at the corticomedullary junction suggests the hematogenous spread of infection, because there is narrowing of the arterioles at the gray/white matter junction. Chronic sequelae of Tubercular Abscess are hydrocephalus, calcifications, atrophy, syringobulbia, syringomyelia. Common complications of CNS TB include hydrocephalus,stroke. The majority of survivors have long-term morbidity with seizures, mental retardation, neurologic deficits, and even paralysis. Differential diagnosis include pyogenic abscess and neoplasm. Management includes multidrug therapy with Isoniazid, rifampin, pyrazinamide, ethambutol or streptomycin.Despite therapy, lesions may develop or increase. Hydrocephalus typically requires CSF diversion.
References:
1.Osborn’s Brain: Imaging, Pathology and Anatomy.
2.Central Nervous System Tuberculosis: An Imaging-Focused Review of a Reemerging Disease-Morteza Sanei Taheri, Mohammad Ali Karimi, Hamidreza Haghighatkhah,Ramin Pourghorban, Mohammad Samadian,andHosein Delavar Kasmaei.(Hindawi)
3.Central Nervous System Tuberculosis Deepak Patkar MD ,, Jayant Narang MD,, Rama Yanamandala MD,, Malini Lawande MD and Gaurang V. Shah MD Neuroimaging Clinics of North America, 2012-11-01, Volume 22, Issue 4, Pages 677-705,
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!