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Chest X-Ray: HIV-Associated Infections

The chest radiograph is the primary imaging tool for evaluating respiratory illness in people living with HIV, particularly in high-burden African settings where it guides diagnosis of tuberculosis and opportunistic infection. Radiographic patterns correlate strongly with the degree of immunosuppression (CD4 count), and interpretation must integrate CD4 status, symptom duration and local epidemiology. Serial comparison is essential because HIV-related disease often evolves rapidly and co-infections are common.

Indications

  • HIV-positive patient with cough, dyspnoea, fever, chest pain or haemoptysis
  • CD4 count <200 cells/mm3 with respiratory symptoms (higher risk of PCP and disseminated disease)
  • Suspected pulmonary or disseminated tuberculosis
  • Suspected Pneumocystis jirovecii pneumonia (subacute dyspnoea, dry cough, hypoxia)
  • Suspected bacterial pneumonia, Kaposi sarcoma or lymphoma
  • Screening before or during antiretroviral therapy and to detect immune reconstitution inflammatory syndrome (IRIS)
  • Assessment of treatment response and detection of complications (effusion, pneumothorax, empyema)

Contraindications & Cautions

  • No absolute contraindication; benefits outweigh minimal radiation risk
  • Pregnancy: justify and shield the abdomen; the PA chest dose is very low but ALARA applies
  • Minimise cumulative dose with repeat imaging by clinically justifying each film
  • Infection control: TB is airborne - image in ventilated areas and follow isolation and PPE protocols to protect staff and other patients
  • Mobile radiography for isolated or critically ill ICU patients to limit transport-related transmission

Patient Preparation

  • Explain the procedure and obtain verbal consent
  • Remove clothing, jewellery and radio-opaque objects from the chest
  • Position for a full inspiratory PA erect film where the patient can stand; lateral view adds value for retrocardiac and hilar disease
  • Supine AP mobile film for immobile/ICU patients, noting positional magnification and altered vascular pattern
  • Retrieve and display prior films for direct comparison
  • Record CD4 count, ART status and symptom timeline on the request to aid interpretation

Technique & Parameters

  • PA erect at ~110-125 kVp with a grid, short exposure to freeze cardiac motion, full inspiration (9-10 posterior ribs)
  • Lateral view for localisation of infiltrates and detection of small effusions
  • AP mobile technique (~80-90 kVp) for bedside ICU imaging; annotate as supine/AP
  • Lateral decubitus film to confirm free-flowing pleural effusion when ultrasound unavailable
  • Resource-limited adjuncts: thoracic ultrasound for effusion characterisation and drainage guidance; digital or portable CXR systems improve access and comparison
  • Correlate with sputum Xpert MTB/RIF, urine LAM and CD4 count rather than relying on imaging alone

Systematic Review

  • Confirm patient identity, projection, rotation, inspiration and penetration adequacy
  • Assess lung volumes and symmetry
  • Review lung zones systematically for consolidation, interstitial change, nodules, cavities and miliary pattern
  • Compare zonal distribution: upper-zone predominance (reactivation TB) vs perihilar (PCP) vs lobar (bacterial)
  • Evaluate hila and mediastinum for lymphadenopathy and masses
  • Inspect pleura for effusion, pneumothorax and thickening
  • Assess heart size, and check for pericardial effusion suggested by an enlarging globular cardiac silhouette (TB pericarditis)
  • Review bones and soft tissues, and directly compare with prior films for progression or resolution

Key Findings & Significance

  • Pneumocystis pneumonia: bilateral, symmetric perihilar interstitial or ground-glass opacities, often with sparing of the periphery; may develop cysts/pneumatoceles and spontaneous pneumothorax; can be normal early
  • Pulmonary TB with preserved CD4: upper-lobe/apical infiltrates and cavitation with possible fibrosis
  • TB with advanced immunosuppression (CD4 <200): atypical pattern - lower/mid-zone infiltrates, mediastinal/hilar lymphadenopathy, miliary micronodules and pleural or pericardial effusion, cavitation often absent
  • Miliary TB: innumerable 1-3 mm nodules evenly distributed throughout both lungs
  • Bacterial pneumonia (Streptococcus pneumoniae common): focal lobar or segmental consolidation with air bronchograms, often at higher CD4
  • Kaposi sarcoma: bilateral peribronchovascular nodular opacities in a 'flame-shaped' perihilar distribution, effusions and adenopathy
  • Lymphoma: mediastinal/hilar mass, nodules, effusions
  • A normal radiograph does not exclude PCP or early disseminated infection

Differential Considerations

  • Diffuse bilateral interstitial/ground-glass pattern -> PCP vs viral/atypical pneumonia vs pulmonary oedema vs miliary TB
  • Upper-lobe cavitation -> post-primary TB vs necrotising bacterial pneumonia vs fungal infection (cryptococcus, histoplasma) vs Nocardia
  • Miliary nodules -> miliary TB vs disseminated fungal infection vs metastatic malignancy
  • Perihilar/peribronchovascular nodular opacities with effusion -> Kaposi sarcoma vs lymphoma vs pulmonary oedema
  • Lobar consolidation -> bacterial pneumonia vs TB vs Kaposi consolidation
  • Mediastinal/hilar adenopathy -> TB vs lymphoma vs Castleman disease vs sarcoidosis
  • Pleural effusion in HIV -> TB (most common) vs bacterial empyema vs Kaposi vs lymphoma

Pearls & Pitfalls

  • Always interpret in the context of the CD4 count: lower counts give more atypical, disseminated and lymphadenopathic TB patterns
  • Symmetric perihilar ground-glass with hypoxia out of proportion to the film strongly suggests PCP - treat empirically and consider CT if available
  • Spontaneous pneumothorax in an HIV patient is PCP until proven otherwise
  • A normal or minimally abnormal CXR does not exclude active TB in advanced HIV; use molecular testing and urine LAM
  • TB pericardial effusion can present as progressive cardiomegaly - look for a globular heart and correlate with echocardiography
  • Kaposi sarcoma pulmonary lesions are typically accompanied by mucocutaneous lesions and bloody pleural effusions that are cytology-negative
  • IRIS can cause paradoxical worsening (enlarging nodes, new infiltrates) weeks after starting ART - do not mistake for treatment failure
  • Beware co-infection: TB plus bacterial pneumonia or PCP can coexist, so a mixed pattern is common

Structured Report

  • State projection, adequacy and whether prior films were available for comparison
  • Describe distribution and character of parenchymal disease (zone, pattern, cavitation, nodularity)
  • Report lymphadenopathy, pleural and pericardial disease, and pneumothorax explicitly
  • Interpret the pattern in the stated CD4 context and comment on most likely infective aetiology
  • Note change from previous imaging (progression, resolution, IRIS)
  • Impression: prioritised differential emphasising TB where relevant, with confidence level
  • Recommend confirmatory testing (Xpert MTB/RIF, urine LAM, sputum, CT chest, echocardiography) and isolation where TB is suspected

References

  • WHO Consolidated Guidelines on Tuberculosis and TB/HIV
  • WHO/UNAIDS guidance on HIV-associated opportunistic infections
  • ACR Appropriateness Criteria: Acute Respiratory Illness in Immunocompromised Patients
  • RadioGraphics: Thoracic Manifestations of HIV/AIDS
  • British HIV Association (BHIVA) opportunistic infection guidelines

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.