Type:
Educational Exhibit
Keywords:
Abdomen, Head and neck, Bones, CT, MR, Ultrasound, Sclerosis, Perception image, Treatment effects, AIDS, Tropical diseases, Infection
Authors:
Z. Wahab1, A. Gangahar 1, J. Zhong1, H. Nejadhamzeeigilani1, H. Bardgett2, M. Kon2; 1Leeds/UK, 2Bradford/UK
DOI:
10.1594/ecr2018/C-2473
Findings and procedure details
TB is most commonly limited to the chest,
but recognition of the radiological findings of extra-pulmonary TB,
which can often mimic other disease entities,
is an important step in accurate diagnosis.
We aim to illustrate the common imaging findings in a system based approach and will cover:
Cardiac
- Rare
-
Via lymphatic spread
-
Imaging findings on CT - pericardial effusion with irregular pericardial thickening (See Fig. 1 )
-
A history of pulmonary TB should raise suspicion
-
Definitive diagnosis can only be made following culture of pericardial fluid aspirate.
[4]
Differentials
-
Cardiac lymphoma
-
Metastasis
Central Nervous System (CNS)
Imaging Findings (See Figure 2-4)
-
Diffuse leptomeningeal enhancement is common (frequently in the interpeduncular cistern of the midbrain as well as extending towards the Sylvian fissures) - see Fig. 2 and Fig. 3
- The TB reactivation is centred on the choroid plexi of the ventricles with subsequent dependent CSF dissemination to the basal CSF spaces - see Fig. 4
- CT may show obliteration of the basal cisterns by isoattenuating or slightly hyperattenuating exudates which will enhance following intravenous contrast administration.
-
Such meningeal exudates can obstruct the resorption of CSF leading to hydrocephalus.
-
MRI has greater sensitivity to basal meningeal enhancement.
-
A possible complication is associated arteritis with resulting infarcts at the perforator territory [3]
-
Small vessel arteritis is also the aetiology of cranial nerve palsies which are very common.
-
Intra-axial tuberculomas occur most often at the junction of grey-white matter.
-
On CT they appear as iso or hypoattenuating small round lesions with variable amounts of surrounding vasogenic oedema.
-
Contrast enhancement occurs only when lesions are solid in the form of ring-enhancement with central caseation.
-
On MRI non-caseating tuberculomas are seen as low signal intensity on T1 and high signal intensity on T2.
Caseating tuberculomas show low signal intensity on T2.
[3]
-
Extra-axial tuberculous leptomeningitis may present with extra-axial fluid collections and empyema formation - see Fig. 5 .
-
Learning point: Always check bone windows to look for bone involvement/destruction.
Differentials
Biopsy or empirical treatment may be required as diagnosis difficult.
Head and Neck
-
Most commonly within the cervical lymph nodes - usually present as bilateral painless cervical lymphadenopathy or historically named ‘scrofula’ (a disease with glandular swellings) [4]
-
Initially seen as homogenous infiltration but later manifests with central necrosis – a feature which is classically but not exclusively seen in TB.
-
CT findings of lymphadenopathy with central low attenuation or caseation or even cystic - see Fig. 6
Differential diagnosis
-
Metastatic infiltration such as squamous cell carcinoma,
papillary thyroid cancer
-
Other pyogenic infections.
Other sites of manifestation within the head and neck are the larynx,
pharynx and temporal bones.
However,
it may be non-specific and chronic cases can show soft tissue masses and bony erosions.
[4]
Musculoskeletal
-
Most common musculoskeletal form of TB is Pott Disease of the spine or Tuberculous spondylitis,
-
Haematogenous spread can be via the venous plexus of Batson.
-
Spread is typically described as sub-ligamentous and affecting mostly the anterior longitudinal ligaments.
-
Results in acute kyphotic deformity or gibbus deformity and it is this angulation,
along with epidural granulation and bony fragments,
that can lead to cord compression.
Cases:
Most common differential diagnosis of TB spondylitis is brucellosis which can present as granulomatous osteomyelitis and caseating granulomas that are acid-fast bacilli.
Haematogenous spread of TB also occurs in long bones and manifests as bone infections such as:
Imaging Findings
-
SITE: Tuberculous arthritis usually starts as a bone infection in the metaphysis and spreads to the epiphysis and then onto the joint surface - see Fig. 11 .
-
Well defined lytic lesions - Within the bones it is shown to cause trabecular destruction,
progressive demineralization and bone and cartilage destruction
-
Little surrounding bone regeneration and periosteal reaction.
-
Cold abscess may also occur [3].
-
In established disease,
plain radiographs may show subtle signs of bone lysis with well-defined borders.
-
CT is more sensitive and will demonstrate cortical and trabecular bone destruction.
-
MRI is useful in differentiating between pyogenic and tuberculous arthritis.
-
TB associated bony erosions are more commonly associated with little subchondral bone marrow oedema,
best demonstrated on T2 fat suppression - see Fig. 11 .
-
Articular cartilage destruction and synovial thickening can be seen in both tuberculous and pyogenic arthritis,
however it is smooth thickening of the synovium that is more common with tuberculous arthritis = learning point
-
Cold abscess cavities tend to have smooth and thin walls with less surrounding inflammation.
-
Other inflammatory arthritis would be a differential; however,
TB tends to be singular (90%) and more common within the knee or hip joints [3].
Additional cases of musculoskeletal TB
-
Fig. 13 - Iliac bone TB with subperiosteal collection and TB myositis
-
Fig. 14 - Tuberculous sacroiliac joint infection with large intra-muscular collection
-
Fig. 15 and Fig. 16 - Spinal TB with large psoas abscess
Abdominal
CT findings - see Fig. 17
-
Circumferential wall thickening of the ileum and caecum
-
Asymmetrical ileocaecal valve thickening.
-
Mesenteric lymph nodes with low attenuation (necrotic) centres.[3]
Differentials
-
Crohn disease - more terminal ileum rather than caecal involvement in TB
-
Caecal or colorectal carcinoma - eccentric caecal wall thickening
-
Small bowel lymphoma - very thick bowel wall,
lack of stricturing
-
Amoebiasis - tends to spare ileum [3]
Other sites:
Genitourinary
- Urinary TB is a common site
- Haematogenous spread to the renal papilla with subsequent antegrade spread in urine and up the vas deferens
-
Manifests within the unilateral periglomerular or peritubular regions - see Fig. 21
-
Incidence 4-8 % in patients with pulmonary TB.
-
Imaging appearance are non-specific and rely on papillary necrosis or parenchymal destruction as suspicion.
-
Learning point: Three or more features of pelvicalyceal thickening,
ulceration and fibrosis with or without strictures make it highly likely to be TB.
-
May also present with a phantom calyx due to an infundibular stricture obstructing a renal segment.
-
LATE features include calcification replacing renal parenchyma or surrounding necrotic areas which occurs 40-70 % of the time.
-
CT can detect papillary necrosis which is shown as moth-eaten appearance of the calyces.
-
Urographic phase imaging may show filling defects within the collecting system secondary to sloughed off papillary necrosis tissue - see Fig. 21 .
-
Fibrotic strictures of the infundibula,
renal pelvis and ureters (typically corkscrew or containing kirk kinks) are highly suggestive of TB which can be appreciated better using excretory urography [3] - see Fig. 22
Differentials for renal TB
A rare form of TB can also manifest within the genital tract,
features are usually non-specific but can affect the testis and epididymis in males or endometrium/ovaries in females.
Usual spread is haematogenous and they are best seen using sonography.
Typically shows as diffuse enlarged homogenous or hetrogenous lesions or nodular enlarged heterogeneously hypoechoic lesions [5] - see Fig. 23 .