Diagnostic imaging Flashcards
For thoracic radiographs, a ___-___% change in diagnosis was found when only 2 views were obtained. ____ and ___ views are more sensitive.
- 12-15%
- VD and right lateral
For target lesions, the PPV for malignancy is ___% when a single nodule is found in liver or spleen on ultrasound. The PPV is ___% if more than one lesion is found.
PPV 1 target lesion: 74%
PPV >1 target lesion: 81%
Contrast-enhanced US improves detection of small blood vessels compared with power doppler imaging because ____________.
reduced motion artifact
Second generation contrast-enhanced US agents contain _______ or ______ within microbubbles. The microbubbles are generally ____, resulting in an intravascular agent that has the flow pattern similar to ___________ and therefore can demonstrate the presence of ________ and can assess arterial, portal, and late phases in the liver.
- perfluorocarbon or sulfur hexafluoride
- <2.5um
- red blood cells
- blood vessels
In both the liver and spleen, a nodule that remains _____ in both early vascular phase and late vascular phase in contrast-enhanced US is more commonly seen with malignant lesions.
hypoechoic
In both the liver and spleen, a nodule that becomes ____ to surrounding parenchyma in both early vascular phase and late vascular phase is most often benign.
isoechoic
For elastography, hard tissues are typically displayed in _____ to _____ colors and soft tissues are displayed in _____ to ____ colors. Tissue stiffness tends to ____ with disease.
- hard: yellow to red
- soft: green to blue
- increase
The most common complications of percutaneous lung biopsy are _______ and ______.
pulmonary hemorrhage and pneumothorax
Hemorrhage associated with ultrasound-guided sampling occurs in ____% and is self-limiting in all but ___%
- <6%
- 1%
The first generation contrast-enhanced US agents were ______________.
air within microbubbles
A paper evaluating ultrasound-guided biopsy and FNA of abdominal structures was performed. Of the 233 biopsy specimens, ___% were considered to be of adequate quality for histologic interpretation. ___% of 70 specimens obtained by fine-needle aspiration correlated with the final diagnosis made during surgical exploration or at necropsy.
- 97%
- 84%
Thin - slice images in CT will have an ______ that can be offset by increasing mAs setting.
increased noise
Keeping the scan field of view only as large as anatomy to be imaged will improve _________.
spatial resolution
CT has decreased _______ compared to radiographs but superior __________ due to reduction in superimpostion.
- decreased spatial resolution
- superior contrast resolution
Accuracy for detecting tracheobronchial lymphadenopathy for CT was ___% compared to ____% for radiographs. Sensitivity was _____% for CT and ____% for radiographs.
CT
- accuracy: 93%
- sensitivity: 83%
Radiographs
- accuracy: 57%
- sensitivity: 0%
In people, the high sensitivity of CT also results in detection of more benign lesions with nodules ______ infrequently developing into metastasis.
< 5 mm
Ground-glass pulmonary lesions are also referred to as ________.
subsolid nodules
About ___% of dogs (mostly with OSA) with ground glass lesions went on to develop radiographically visible metastasis in one pilot study.
75%
Up to ___% of ground glass pulmonary lesions are caused by transient inflammation or hemorrhage.
70%
Pure ground-glass lesions ______ have a high probability of malignancy. Those ____ are considered benign.
- > 8mm
- <4mm
CT angiography can improve detection of small tumors, such as ____, and may be a more accurate assessment of _____ and _______ masses.
- insulinoma
- thyroid and cranial mediastinal masses
CT is used for RT planning because it provides a map of ________ information that is used by most planning computers to calculate dose distribution.
electron density
CT is more sensitive than radiographs in the detection of pulmonary metastasis and allows for detection of nodules as small as _____ in diameter compared with ______ for radiography
- 1mm
- 7-9 mm
A study of _____ showed no difference in evaluation of peritumoral lesions between CT and MRI.
FISS
_____ MRI images provide good spatial resolution to assess anatomy and are used with contrast to show vascular enhancement of tissues.
T1-weight images
____ MRI images are water-weighted sequences that provide high-contrast images of water-dense pathology.
T2-weighted images
On BOTH T1 and T2-fast spin echo sequences on MRI, ____ has a high signal intensity (bright) that can mask the margins of pathology.
Fat
The use of fat suppression techniques on T1 post-contrast and T2 images is important in cancer imaging to allow for clear assessment of the extent of pathology. _______ is a fat suppression technique.
STIR
___________ measures the random Brownian motion of water molecules in a voxel of tissue on MRI.
Diffusion-weighted imaging
_________- provides similar results to PET/CT in people with diffuse B-cell LSA. Images are suboptimal for ________.
- Diffusion-weighted imaging MRI
- skeletal system
Hepatocyte-specific MR agents, such as ______, accumulate in normal hepatocytes, potentially allowing for differentiation between benign liver nodules and metastatic lesions.
gadoxetate disodium
Nuclear scintigraphy has low _______, lacks ____, and is highly sensitive for _______.
- low spatial resolution
- lacks specificity
- increased metabolic activity
Radiographs require at least ___-___% change in mineral density for bone lesions to be detected.
30-50%
The most commonly used radiopharmaceutical for PET/CT is ______, which is a glucose analog.
F18-FDG
FDG is transported into hypermetabolic cells and becomes trapped after phosphorylation by _____ as it is not a suitable substrate for _______. Positrons emitted from F-18 create _________ that travel 180 degrees from each other and allows for imaging.
- hexokinase
- glucose-6-phosphatase
- two annihilation photons
_____ is a bone specific radiopharmaceutical for PET/CT that has been shown to be superior in detecting bone metastasis compared to _______.
- F-18 NaF
- SPECT imaging with Tc99m-methyl diphosphonate
_____ is thymidine analog used to detect proliferating tissues in PET/CT. It reflects _________.
F-18 FLT
DNA synthesis
PET/CT functional imaging of tumor hypoxia using dogs with nasal tumors injected with _______ has been performed for radiation boost planning.
Cu-ATSM
The ________ of normal tissues must be known to accurately interpret PET images.
baseline metabolic rate
_______ is a semiquantitative measure of FDG uptake that is directly proportional to metabolic activity.
- standardized uptake value (SUV)
In humans, an SUV max ____ is predictive of malignancy in patients with solitary pulmonary nodules.
> 2.5
What PET/CT radiopharmaceutical was shown to correlate with grade of mast cell tumors in a small group of dogs?
F-18 FDG
CT assessment of sternal LNs suggest a sternal LN to second vertebrae ratio of ____ and a pre-contrast attenuation of _________ is highly predictive of malignancy.
- > 1
- 37.5 HU or higher
A change in change of a LN from ______ to ______, as indicated by a short axis-to-long axis ration of ____, and loss of definition of the ____ is seen more frequently in malignant LNs.
- oval to round
- > 0.7
- LN hilus
Use of _______ contrast medium in lymphangiography results in retention of the agent in LN for up to ____ after injection, which can aid in follow-up LN assessment. Contrast voids are consistent with new metastatic lesions.
- iodized oil
- 2 months
__________ is superior at identifying intramedullary margins on MRI in dogs with appendicular OSA.
T1-weighted non-contrast images
SPECT detects ____ emissions for Technetium 99m.
gamma
Preoperative helical contrast CT was evaluated in hepatic lesions. What findings were consistent with HCC, nodular hyperplasia, and metastatic liver lesions?
HCC
- heterogenous; hyper-, iso-, and hypoenhancement in both arterial and portal venous phases (85%)
Nodular hyperplasia
- homogenous; hyper- and isoenhancement in both portal venous and delayed phases (93%)
Metastasis
- homogenous; hypoenhancement in both arterial and portal venous phases (89%); 55% also had homogenous hypoenhancement in delayed phase
What has been used with PET/CT for the detection of response to cytotoxic chemotherapy in dogs with non-Hodgkin’s LSA?
F-18 FLT
What is the MOA of nitroimidazole-like uptake for PET/CT and tissue hypoxia?
reduction of RNO2 radicals and RNHOH compounds in hypoxic conditions then covalent binding to macromolecules
What is the MOA of Cu-ATSM in PET/CT and tissue hypoxia?
reduction of Cu(II)-ATSM complex into Cu(I)-ATSM and dissociation of Cu(I) in hypoxic conditions, then Cu(I) binding to intracellular proteins
[124I]-cG250 and [89Zr]-cG250-F(ab’)2 recognizes _______ in PET/CT.
carbonic anhydrase IX
18-F has a half-life of _____.
110 minutes
_______ is a PET/CT tracer that detects in vivo activity of aromatic 1-amino acid decarboxylase of the dopaminergic system and is used to detect neuroendocrine tumors and Parkinson-related disorders
18F-fluoro-L-DOPA
______ is a PET/CT tracer that is a precursor of biosynthesis of an essential element of phospholipids of the cell membrane. It is used to detect well differentiated tumors with low glucose uptake (ie, prostate cancer).
11C-Choline
________ is a PET/CT tracer that is a structural analogue of 5-a-dihydrotestosterone that can be used to detect metastatic and recurrent prostate cancer.
F18- FDHT
_____ is a PET/CT tracer that is a metabolic substrate for synthesis of cholesterol and lipids with renal clearance. It is used to detect prostate cancer and renal tumors
11C-Acetate
What is the MOA of the PET/CT tracer, F-18 NaF?
Fluoride ion is switched with the hydroxyl group in the bone crystals forming fluoroapatite, thus where bone turnover is greatest, there are high deposits
_____ is a PET/CT tracer that is an important amino acid for the protein synthesis process that does not accumulate in normal brain tissue, thus it have been most useful for detecting brain tumors
18C-Methionine
The dominant signal intensities of T1-weighted images are as follows:
- Fluid:
- Muscle:
- Fat:
- Grey matter:
- White matter:
- Fluid: low signal (black)
- Muscle: intermediate signal (grey)
- Fat: high signal (white)
- Grey matter: intermediate (grey)
- White matter: hyperintense compared to grey matter (white-ish)
______ MRI images are good to evaluate borders between brain and CSF and BBB disruption.
T1-weighted images
_______ MRI images are used to distinguish soft tissues.
T2-weighted images
The dominant signal intensities of T2-weighted images are as follows:
- Fluid:
- Muscle:
- Fat:
- Grey matter:
- White matter:
- Fluid: high signal (white)
- Muscle: intermediate signal (grey)
- Fat: high signal (white)
- Grey matter: intermediate (grey)
- White matter: hypointense compared to grey matter (dark-ish)
How is FLAIR different than T2-weighted images? Most pathology is _______ and what is it good for?
- free CSF is suppressed –> black
- bright
- good for lesions near ventricles and sucli and sometimes improves white/grey matter distinction
Dural tail is seen in ___% of cases of meningioma but is not specific. Bone changes, such as osteolysis and hyperostosis occur in ___%.
72%
20%
Describe intensities on MRI for meningioma.
T1: isointensity to slight hypointensity relative to grey matter
T2: isointensity to slight hyperintensity relative to grey matter
Contrast (Gd): avid, homogenous enhancement
What is the appearance of myelofibrosis and mastocytosis in bone marrow on MRI and why?
Leads to sclerosis so very dark marrow on both T1 and T2 series
