PGMI evaluation system

PGMI (Perfect, Good, Moderate, Inadequate) is a methodof evaluation of clinical image quality in mammography developed by the UnitedKingdom Mammography Trainers Group with the support of the Royal College ofRadiographers, aimed to ensure the maintenance of a highstandard of mammography in Breast Screening and to facilitate a method of externalaudit.

Criteriafor image assessment PGMI based:

1. All

1. all breast tissue imaged (fat tissue visualisedposterior to glandular tissue) 

   2. Correct

2. correct image identification clearly shown:

    •

   • date ofexamination

     • client

   • client identification—name and (number and/or date of birth)

     • side

   • side markers

     • positional

   • positional markers

     •

   • radiographer identification

     3. Correct

3. correct exposure according to workplace requirements

   4. Good

4. good compression

   5. Absence

5. absence ofmovement

   6. Correct

6. correct processing

   7. Absence

7. absence ofartefacts

   8. No

8. no skinfolds

   9. Symmetrical

9. symmetrical images

Specificpositioning criteria for CC view:

• 1. Allall breasttissue imaged:

  • medial

  • medial border well demonstrated

    •

  • nipple inprofile (retro-areolar tissue well separated)

    •

  • nipple inmidline of imaged breast

    • posterior

  • posterior nipple line (PNL) within 1cm of PNL on MLO view

Specificpositioning criteria for MLO view:

• 1. Allall breasttissue imaged:

  • pectoral

  • pectoral muscle shadow to nipple level

  •

• full widthof pectoral muscle

  •

• nipple inprofile (retro-areolar tissue wellseparated)

  •

• infra-mammary fold well demonstrated

  •

• PNL within 1cm of PNL on CC view

CC images classification:

P = Perfect images

•

• CC images meet criteria for imageassessment 1−9

G = Good images

• 1.All breast tissue imaged (axillary portion of breast notto be included at expense of medial portion)

  • all

  • all postero-medial tissue visualised

    •

  • nipple inprofile

    •

  • nipple inmidline of imaged breast
• 2- 6. CC images meet criteria for image assessment2−6inclusive forcategorisation as G
• 7- 9. CC images displaying minor degrees ofvariation in criteria for imaging assessment 7, 8 and 9 will be accepted forcategorisation as G

M = Moderate images (Acceptablefor diagnostic purposes)

1. Most

1. Most breast tissue imaged 

   •

   • nipple notin profile but clearly distinguishablefrom retro-areolar tissue

     •

   • nipple notin midline (significantbias)

     2.

2. Correct(ed) image identification

   3. Correct

3. Correct exposure

   4. Adequate

4. Adequate compression

   5.

5. Absence ofmovement

   6. Correct

6. Correct processing

   7. Artefacts

7. Artefacts which do not obscure the image

   8.

8. Skin foldswhich do not obscure the breast tissue

   9.

9. Asymmetrical images

I = Inadequate images 

1.

1. Significant part of the breast not imaged

   2. Incomplete

2. Incomplete or incorrect identification

   3. Incorrect

3. Incorrect exposure

   4. Inadequate

4. Inadequate compression hindering diagnosis

   5. Blurred

5. Blurred image

   6. Incorrect

6. Incorrect processing

   7. Overlying

7. Overlying artefacts

   8.

8. Skin folds obscuring the image

MLO images classification:

P = Perfect images

•

• MLO images meet criteria for imageassessment 1−9

G = Good images

• 1.All breast tissue imaged

  • pectoral

  • pectoral muscle well demonstrated

    •

  • nipple inprofile

    •

  • infra-mammary fold (IMF) well demonstrated
• 2- 6. MLO images meet criteria for image assessment2−6inclusive forcategorisation as G
• 7- 9. MLO images displaying minor degrees ofvariation in criteria for 
• imaging assessment 7, 8 and 9 will be accepted forcategorisation as G

M = Moderate images (Acceptable for diagnostic purposes)

1. Most

1. Most breast tissue imaged.

   • Pectoral

   • Pectoral muscle not to nipple level butposterior breast tissue adequatelyshown

     •

   • nipple notin profile but clearly distinguishablefrom retro-areolar tissue 

     •

   • IMF notclearly demonstrated but breast tissue adequately shown

     2.

2. Correct(ed) image identification

   3. Correct

3. Correct exposure

   4. Adequate

4. Adequate compression

   5.

5. Absence ofmovement

   6. Correct

6. Correct processing

   7. Artefacts

7. Artefacts which do not obscure the image

   8.

8. Skin foldswhich do not obscure the breast tissue

   9.

9. Asymmetrical images

I = Inadequate images 

1.

1. Significant part of the breast not imaged

   2.

2. Incomplete or incorrect identification

   3.

3. Incorrect exposure

   4.

4. Inadequate compression hindering diagnosis

   5.

5. Blurred image

   6.

6. Incorrect processing

   7.

7. Overlying artefacts

   8.

8. Skin folds obscuring the image

RECOMMENDED STANDARDRecommended standard

(Image classification in relation to PGMI system to maximize high qualityof images and minimise technical repeats)

A minimum of50% of an audit of 50 randomly selected cases should be graded in: 

• P or G categories(75% desirable)

or

P or G or M categories (97% desirable)

Repeat rate:

<3% of consecutive images to be classified "Inadequate"