HRCT LUNG

 

Ref--High -resolution CT of Lung (Webb)

HRCT LUNGS --BASIC

 

All are true regarding HRCT of lungs except

a.the bronchus and homologous pulmonary artery are of similar diameter in normal subjects

b.B/A ratio refers to internal diameter( luminal ) of bronchus (B) divided by diameter of adjacent pulmonary artery(A)

c.B/A ratio in normal subjects averages .45 to .60

d.B/A ratio >1 is generally regarded as abnormal

e.B/A ratio >1 in normal subjects has been associated with increasing age

ANS --- c

B/A ratio in normal subjects averages .65 to .70

 

 

 

dose reduction in HRCT

 

Q.Techniques for dose reduction in HRCT are all

 except 

a.reduction in mA and kVp

b.interspaced imaging

c.use of Iterative reconstruction

d.use of bismuth shield          

e.use of Filtered back projection reconstruction

ANS ---e

Radiation

 Procedure -------------effective radiation dose (mSv )

1.background radiation dose --2.5mSV

2.PA CHEST radiograph ---.05mSv

3.MD-HRCT standard technique--- 4 to 7 mSv 

MCQ HRCT

Q. All are true regarding HCRT of lung except

a.the term first used by Todo et al.

b.MDCT allow faster acquisition and higher image quality of HRCT

c.slice thickness (1 to 1.25mm)

d.use of high spatial frequency algorithm

e.use of overenhancing algorithm

ANS----. e

High resolution CT include(  I) the use of thin collimation axial scan or thin section reconstruction of volumetric data obtained using MDCT and narrow detector width (less than or equal to 1.5mm) (II) image reconstruction with high spatial frequency ( sharp or high –resolution ) alogrithm .

Use of thin section ( less than or equal to 1.5mm ) is essential if spatial resolution and lung details are to be optimized .The image with thinner section shows clearer definition of the fissure ,vessel walls and walls of the cyst .The use of 2.5 to 5mm slice thickness should not be considered adequate for HRCT .

Boedeker et al .classified different reconstruction algorithm from different vendors into three main categories : standard ,sharp,and overenhancing

Reconstruction of images using sharp,high spatial frequency or high resolution algorithm ( bone algorithm ) reduces image smoothening and increases spatial resolution ,making structures appear sharper .Using  a high –resolution algorithm is a critical element in performing HRCT .

Overenhancing algorithm interefere with the ability to distinguish certain findings like reticulation and honeycombing .

NEURODEGENERATIVE DISEASES

 

AMYLOID IMAGING --MCQ

 

Q1 .Radiopharmaceuticals used for BETA amyloid imaging  are all  except 

a, 18F-florbetapir

b.18Fflorbetaben

c. 18F-flutemetamol

d.123I-Ioflupane

1.Ans--d

Q2.All are true regarding beta amyloid imaging except 

a.uptake by white matter normal 

b.inceased cortical uptake abnormal

c.cerebellum used as internal control 

d.crebellum shows most heavy amyloid depostion 

2Ans---d

A relatively new group of contrast agents exists that allows visualization of abnormal amyloid deposition . Although the original agent was carbon 11–Pittsburgh compound B, the current major radiopharmaceuticals in this group are all tagged with 18F and include 18F-florbetapir, 18Fflorbetaben, and 18F-flutemetamol. T

At neurologic imaging, normal white matter takes up these agents. The mechanism is not well understood, but research suggests it may bind to myelin-binding proteins and could be used in the workup of demyelinating diseases

At β-amyloid imaging, areas of increased cortical uptake are considered abnormal and correspond to cortical deposition of β-amyloid plaques. An internal control is used to establish a normal uptake pattern, with the cerebellum typically used to compare gray-white differentiation, as the cerebellum rarely has abnormal amyloid accumulation.

RADIOGRAPHICS 

WORK-UP of patients with suspected dementia

 

WORK-UP of patients with suspected dementia 

MCQ MRI BRAIN

 

Above MRI image ( coronal section) of brain shows 

a.extraaxial sol

b.edema 

c.left ward midline shift 

d.tansfalcine herniation 

e.all

ANS---e ( all )

CINGULATE ISLAND SIGN

Q.CINGULATE ISLAND SIGN on FDG -PET SCAN of brain is noted in 

a.Alzheimer disease

b.DLB 

c.both \

d.none 

ANS---b ( DLB)

----The typical pattern of hypometabolic activity in Alzheimer disease on 18F-FDG PET images involves the parietotemporal region, precuneus, and posterior cingulate gyrus, with sparing of the sensorimotor strips and occipital region, which usually corresponds to the atrophic changes depicted on structural images. 

----In patients with DLB, 18F-FDG PET images show asymmetric decreased activity in the frontotemporal lobes similar to that depicted in Alzheimer disease. However, there is preserved metabolism of the posterior cingulate cortex, resulting in the so-called cingulate island sign. Alzheimer disease almost invariably involves the posterior cingulate gyrus, and this is a useful differentiating factor. There is hypometabolism of the occipital lobes, which is helpful to differentiate DLB from typical Alzheimer disease.

MRI PROTOCOL FOR MS AND ITS FOLLOW-UP STRATEGY

 

FROM RADIOGRAPHICS 

Spectrum of Acquired demyelinating disease

 

MOG-Antibody -Associated disease

 

from radiographics 

The triangle of GUILLAIN and MOLLARET

 

Hypertrophic Olivary Degeneration.—This is a rare condition characterized by a lesion located in the triangle of Guillain and Mollaret, formed by the red nucleus, inferior olivary nucleus, and contralateral dentate nucleus

From Radiographics 

HOT CROSS BUN SIGN

 

FROM RADIOGRAPHICS 

Benedict Waving Cloud for glimpse OF Pari

 MID-BRAIN SYNDROME 

1.Weber syndrome is caused by infarction of the oculomotor nucleus and cerebral peduncle in the ventromedial midbrain 

2.Benedicts syndrome(para-median mid  brain syndrome ) ---- involve the fascicles of the oculomotor nerve and red nucleus

3.Claude syndrome involve red nucleus 

4.Parinaud Syndrome.—Parinaud syndrome (dorsal midbrain syndrome) is caused by compression of the tectal plate near the level of the superior colliculus from a space-occupying lesion located in the posterior commissure or pineal region

FROM RADIOGRAPHICS 

MCQs Primary mitochondrial disorder

 

1.All are true regarding Primary Mitochondrial disorder except 

a.caused by variants in mtDNA

b.caused by variants in nDNA 

c.occurence at any age 

d.commonly affects pediatric CNS 

e.affect organ highly dependent on anaerobic metabolism 

1.ANS --e

 Primary mitochondrial disorder (PMD) is caused by pathogenic variants in mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) that commonly affect the pediatric central nervous system (CNS), lacking pathognomonic imaging findings. 

 PMDs are clinically heterogeneous, may occur at any age, and manifest with a broad range of multiple symptoms. They can affect any organ or tissue but usually affect those organs or tissues that are highly dependent on aerobic metabolism and that have high energy requirements, such as the CNS, heart tissue, and skeletal muscle.

Impaired ATP production is the common outcome of all PMDs. It is well known that certain neuronal populations, including large and long projection neurons (particularly those with sparsely myelinated axons) and fast-spiking interneurons, are especially dependent on oxidative metabolism and extremely susceptible to respiratory chain impairment

2.Common CNS Primary mitochondrial disorders are all except

a. Leigh syndrome

b. Sturge-Weber syndrome  

c.MELAS, 

d.Kearns-Sayre syndrome,

e. Leber hereditary optic neuropathy (LHON)

2.ANS ---b

 Common CNS PMDs with characteristic imaging phenotypes include ----

Leigh syndrome

POLG-RDs

 MELAS

 Kearns-Sayre syndrome

Leber hereditary optic neuropathy (LHON)

pyruvate dehydrogenase (PDH) complex deficiency

coQ10 deficiency

 leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL).

3.The spectrum of MR neuroimaging findings of PMDs includes

a. basal ganglia signal intensity changes

b.basal ganglia calcification

c. callosal dysgenesis ortical 

d.subependymal cysts

e.all

3.ANS---e

The spectrum of MR neuroimaging findings of PMDs includes ---

basal ganglia signal intensity changes

basal ganglia calcification

 cortical signal intensity changes and malformations

 subependymal cysts

 white matter changes (leukoencephalopathy, white matter cavitation, callosal agenesis or dysgenesis, and delayed myelination or hypomyelination).

MRI spectrum of LEIGH syndrome ---

RADION-INDUCED BRAIN INJURY

Radiation -induced brain injury 

In the central nervous system (CNS), the effects of radiation can be roughly divided into effects on vascular endothelial cells and direct effects on neuroglial cells, in particular the oligodendroglial cells

 On the basis of the time of expression, radiation-induced injury can be divided into three phases: acute, early delayed, and late delayed. Acute and early delayed injuries are usually transient and reversible, whereas late delayed injuries are generally irreversible.

 To correctly interpret imaging studies, radiologists should maintain familiarity with the expected imaging appearances after RT and carefully distinguish them from tumor recurrence. Keys to recognizing radiation-induced changes at follow-up imaging are knowledge of (a) the amount of time elapsed since RT, (b) the location of the target lesion, and (c) the amount of normal structures included.

 At imaging, radiation-induced leukoencephalopathy is characterized by cerebral white matter high signal intensity on T2-weighted or fluid-attenuated inversion-recovery (FLAIR) images, usually without enhancement or significant mass effect. It typically exhibits diffuse and symmetric involvement after whole-brain RT, with relative sparing of the subcortical U-fiber, corpus callosum, and gray matter. White matter lesions usually develop around the periventricular white matter at the beginning and progress to diffuse white matter changes with varying degrees of cerebral atrophy over months or years.

 Currently, the only method of distinguishing pseudoprogression and true tumor progression is to perform follow-up examinations of the patient because conventional MRI does not allow differentiation of the two conditions. Imaging may be regularly performed at 2–3-month intervals throughout the follow-up period, although the frequency of imaging can be variable across institutions. In clinical practice, the following features can be helpful: (a) presence of symptoms and (b) methylation status of the MGMT gene promoter.

 Prompt diagnosis of radiation-induced spinal cord myelopathy can be difficult because symptoms can vary, and MRI findings are nonspecific and can vary depending on the timing of MRI with respect to radiation exposure. Some imaging features may be useful in incorporating radiation-induced spinal cord myelopathy in the differential diagnosis, such as the longitudinally extensive cord signal intensity pattern corresponding to the radiation field and demonstration of T1-weighted hyperintense marrow signal changes in vertebrae included in the radiation field.

RADIOGRAPHICS