Glossary of radiological classifications

The objective of medical image processing is to extract useful information for diagnosis from the acquired images, to reveal details that are difficult to perceive while avoiding the creation of artifacts. The processing phase uses tools and algorithms, which can be applied to the digital image. One of the steps in the image processing chain is classification. There are several classification methods, they aim to group the elements of a set X, of any nature, in a limited number of classes.

Here we will focus on the classifications that are commonly used in daily practice and used as a reference by radiologists and radiology interns.

Modic changes

Modic changes on MR imaging are signal intensity changes in vertebral body marrow adjacent to the endplates of degenerative discs.

Fazekas scale for WM lesions

The Fazekas scale is used to simply quantify the amount of white matter T2 hyperintense lesions usually attributed to chronic small vessel ischemia, although clearly not all such lesions are due to this.

   Periventricular Lesions

0 No lesions
1 Caps or thin line
2 Smooth halo
3 Extension into the white matter

   White matter lesions

0 No lesions
1 Punctate foci
2 Beginning confluence of foci
3 Large confluent areas

Garden classification

Garden classification predicts the development of Avascular necrosis of the hip. Garden described particular femoral neck and acetabular trabeculae patterns which can assist in recognizing differences within this classification system.

• Type 1: stable fracture with impaction in valgus.
• Type 2: complete but non-displaced.
• Type 3: partially displaced (often externally rotated and angulated) with varus displacement but still has some contact between the two fragments.
• Type 4: completely displaced and there is no contact between the fracture fragments.

Bosniak classification

The new version of the Bosniak classification establishes 5 different stages according to the CT aspect of the cyst. The radiological features taken into account are the homogeneous appearance of the cyst, the presence of thicker or thinner intracystic septa, the thickness and enhancement of the cyst wall after injection of contrast medium and the presence of calcifications.

Bosniak I:

- Benign simple cyst with a hairline-thin wall that does not contain septa, calcifications, or solid components
- water attenuation
- does not enhance

- % malignant : ~ 0
- No intervention is needed

Bosniak II:

- Benign cystic lesion that may contain a few hairline-thin septa in which perceived (not measurable) enhancement may be appreciated
- Fine calcification or a short segment of slightly thickened calcification may be present in the wall or septa
- Uniformly high-attenuating lesions (< 3 cm) that are sharply marginated and do not enhance are included in this group.

- % malignant : ~ 0
- No intervention is needed

Bosniak IIF:

- Cysts may contain multiple hairline-thin septa
Perceived (not measurable) enhancement of a hairline-thin smooth septum or wall can be identified;

- Possible minimal thickening of wall or septa, which may contain calcification that may be thick and nodular, but no measurable contrast enhancement is present
- No enhancing soft-tissue components
- Totally intrarenal nonenhancing high-attenuating renal lesions (>3 cm) also included in this category(lesions generally well marginated)

- % malignant : ~ 5 %
- Thought to be benign but need follow-up to prove their benignity by showing stability

Bosniak III

- Cystic masses with thickened irregular or smooth walls or septa and in which measurable enhancement is present;

- % malignant : ~ 50%
- Need surgical intervention in most cases with histologic diagnosis, as neoplasm cannot be excluded

- This category includes complicated hemorrhagic or infected cysts, multilocular cystic nephroma, and cystic neoplasms

Bosniak IV

- Clearly malignant cystic masses that can have all of the criteria of category III but also contain distinct enhancing soft-tissue components independent of the wall or septa

- % malignant : ~ 100%
- Need to be removed

Magerl Classification

Magerl classification of thoracolumbar spinal fractures relies exclusively on CT findings.

Type A.
Vertebral body compression

A1. Impaction fractures
A2. Split fractures
A3. Burst fractures

Type B
Anterior and posterior element injury with distraction

B1. Posterior disruption predominantly ligamentous (flexion-distraction injury)
B2. Posterior disruption predominantly osseous (flexion-distraction injury)
B3. Anterior disruption through the disc (hyperextension-shear injury)

Type C
Anterior and posterior element injury with rotation

C1. Type A injuries with rotation (compression injuries with rotation)
C2. Type B injuries with rotation
C3. Rotational-shear injuries

ACR - BI-RADS Classification 

This classification, established by the American College of Radiology, makes it possible to establish a common stance based on an abnormality detected on breast imaging.

It can be unilateral or bilateral depending on the study of one or both breasts.

Classification of mammographic images into six categories according to the degree of suspicion of their pathological character (apart from constructed images and variants of the normal) - Correspondence with the BIRADS system of the American College of Radiology (ACR).

0: Incomplete: Your mammogram or ultrasound didn’t give the radiologist enough information to make a clear diagnosis; follow-up imaging is necessary
1: Negative: There is nothing to comment on; routine screening recommended
2: Benign: A definite benign finding; routine screening recommended
3: Probably Benign: Findings that have a high probability of being benign (>98%); six-month short interval follow-up
4: Suspicious Abnormality: Not characteristic of breast cancer, but reasonable probability of being malignant (3 to 94%); biopsy should be considered
5: Highly Suspicious of Malignancy: Lesion that has a high probability of being malignant (>= 95%); take appropriate action
6: Known Biopsy Proven Malignancy: Lesions known to be malignant that are being imaged prior to definitive treatment; assure that treatment is completed

Some experts believe that the single BI-RADS 4 classification does not adequately communicate the risk of cancer to doctors and recommend a subclassification scheme:

4A: low suspicion for malignancy
4B: intermediate suspicion of malignancy
4C: moderate concern, but not classic for malignancy

Scheltens score for of Alzheimer Disease on MRI

The MTA-score (Scheltens) should be rated on coronal T1-weighted images. on a slice through the corpus of the hippocampus (level of the anterior pons).

The scale  is based on a visual score of the width of the choroid fissure, the width of the temporal horn, and the height of the hippocampal formation.

score 0: no atrophy
score 1: only widening of choroid fissure
score 2: also widening of temporal horn of lateral ventricle
score 3: moderate loss of hippocampal volume (decrease in height)
score 4: severe volume loss of hippocampus

< 75 years: score 2 or more is abnormal.
> 75 years: score 3 or more is abnormal.

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