A standardised data collection form, adapted from the PGMI (Perfect, Good, Moderately Good, Inadequate) system, was used to assess the quality of mammograms [4] . The form contained 16 criteria divided into two main categories: 8 criteria relating to patient positioning and 8 criteria relating to the photographic quality of the image. Data were extracted from the radiology department’s digital and physical archives, including raw images and associated metadata (date, anonymised patient identification, technical parameters).

The 8 positioning criteria were selected to reflect the anatomical and technical requirements necessary for optimal radiological interpretation in accordance with the recommendations of the PGMI system [4] . These criteria are:

These criteria were chosen because they correspond to the international PGMI standards, widely validated for their ability to identify positioning errors affecting diagnostic sensitivity [3] [4] . Their relevance in the context of Douala General Hospital lies in their universal applicability, regardless of local constraints (equipment or training).

The 8 photographic quality criteria have been selected to assess the technical aspects of imaging, which are essential for clear and accurate reading [3] . These criteria are:

These criteria were chosen because of their importance for diagnostic reliability and their compatibility with the equipment available at the Douala General Hospital (digital mammography). They also allow comparison with international studies using PGMI [3] [4] .

Each image was independently assessed by a radiologist trained in the use of the PGMI system. Criteria were graded according to the four PGMI levels: ‘P’ (perfect, no defects), ‘G’ (good, minor defects not affecting diagnosis), ‘M’ (moderately good, defects partially limiting interpretation), and ‘I’ (inadequate, defects rendering the image non-diagnostic) [4] . An image was globally classified according to the most unfavourable criterion in accordance with PGMI guidelines [4] . The results were expressed as percentages for each criterion and incidence (CC and MLO), then summarised in tables to facilitate interpretation.

The study used anonymised data extracted from the archives of the Douala General Hospital and did not require individual patient consent. The study was approved by the internal committee of the Douala General Hospital, which verified its compliance with local and international ethical standards for secondary data research [1] .

The positioning criteria revealed significant differences between the CC and MLO incidences, as summarised in Table 1 .

For CC, the majority of images reached a satisfactory level (‘P’ or ‘G’). Good visualisation of the posterior and medial breast tissue was achieved in 80.5% of cases, reflecting an effective positioning technique for these areas. The nipple was well exposed in 74.5% of images, a key indicator for radiological interpretation. However, the presence of the pectoralis muscle was only observed in 6% of cases, suggesting a limitation in field extension.

On the other hand, MLO incidence showed more heterogeneous results. The lower part of the breast was clearly visible in 85% of cases, and the angle of the pectoral muscle exceeded 15˚ in 85% of images, which are strong points for this type of approach. However, the length of the pectoralis muscle was appropriate in only 60.5% of cases (56% ‘G’, 4.5% ‘P’), and the infra-mammary fold remained poorly visualised in 92.5% of images (only 7.5% ‘P’ or ‘G’), highlighting the technical challenges involved in optimal positioning.

The photographic criteria, assessed independently of incidence, showed an overall high performance (see Table 2 ). All images (100%) were judged ‘P’ for the spread of the mammary gland, contrast, sharpness, and absence of artifacts, indicating reliable equipment and careful technical execution. The identification of the images was also 100% correct. However, the presence of folds was noted in 45.5% of cases, 22% of which were likely to interfere with reading, resulting in a ‘G’ or ‘I’ classification for this specific criterion.

In general, mammograms in CC incidence were of higher quality (mostly ‘P’ or ‘G’) than MLO mammograms, where poor positioning (particularly in the infra-mammary fold) limited the scores. The photographic quality remains an asset, although the folds require particular attention to avoid misinterpretation. It should be noted that this study did not consider correlating image quality with diagnostic results (presence or absence of lesions), which limits interpretation of the direct impact of these defects on clinical performance.

The CC images achieved ‘P’ and ‘G’ levels for most positioning criteria (80.5% for posterior/medial breast tissue), close to the results of Richli Meystre and Bulliard (75% and 88%, respectively) [13] . Nipple clearance (74.5%) exceeded their 51%, suggesting a technique adapted to the local context. On the other hand, MLO incidence shows shortcomings: poor visualisation of the infra-mammary fold (7.5% compared with 37% in some cases) and insufficient length of the pectoral muscle in 39.5% of cases limit the quality to ‘G’ or ‘M’. These defects may reduce the detection of lesions in the axillary or inferior regions, which are critical for diagnosis [6] .

Optimal performance (100% ‘P’) for contrast, sharpness, and absence of artifacts reflects functional equipment, surpassing the 81% - 98% of Richli Meystre and Bulliard [13] . Creases (45.5%), although less of a problem than the 22% that were troublesome, indicate a need for improvement in compression or positioning.

Analysis of the results reveals that sub-optimal positioning in MLO is mainly related to two criteria: poor visualisation of the infra-mammary fold (7.5% ‘P’ or ‘G’) and insufficient length of the pectoralis muscle (60.5% ‘P’ or ‘G’). Several specific factors may explain these shortcomings. Firstly, inadequate mobilisation of the breast during positioning could prevent full exposure of the inframammary fold, often due to insufficient breast lifting technique by the technologist or patient reluctance due to discomfort [8] . Secondly, the reduced length of the pectoralis muscle could be the result of a positioning angle that is too shallow or a misaligned compression, limiting the extension of the field towards the axillary tissues [6] . Thirdly, the lack of standardised training for technologists, combined with a high workload, may lead to variations in the application of MLO protocols. Finally, the physical characteristics of patients (e.g., small breasts or obesity) could complicate positioning, a factor little documented in African contexts but relevant at Douala General Hospital [10] .

These results confirm an overall satisfactory quality, supporting diagnostic reliability at Douala General Hospital. However, weaknesses in MLO highlight the need for targeted interventions. Compared with European contexts [6] , these results reveal potential for optimisation despite limited resources.

Implementing improvement initiatives would have an impact on human, material, and financial resources. Training would require time and qualified trainers, potentially disrupting busy schedules. Technical adjustments would involve costs for maintenance or updating of mammograms, which would be difficult to meet within a constrained hospital budget [8] . Obstacles also include the weak culture of systematic screening in Cameroon [2] and the lack of inter-observer data in our study.

To address the identified gaps in MLO, the following recommendations are proposed:

The small sample (100 cases) and the absence of inter-observer data could influence the generalisation of the results. The study of patient-related factors remains exploratory in the absence of specific data. In addition, this study did not consider correlating image quality with diagnostic results (presence or absence of lesions detected), which limits our ability to assess the direct impact of positioning errors or folds on the clinical performance of screening. This omission restricts the conclusions to a technical assessment with no established link to diagnostic efficacy.