Imaging of diaphragm and its pathologies

1. IMAGING OF DIAPHRAGM
AND ITS PATHOLOGIES
Dr. Milan Silwal
Resident, MD Radiodiagnosis
NAMS

2. Presentation outline
• Relevant anatomy
• Imaging modalities
• Anatomical variants
• Diaphragmatic dysfunction
• Diaphragmatic rupture
• Diaphragmatic tumours
• Diaphragmatic hernia
• Summary

3. Diaphragm
• Dome-shaped muscle that separates the thoracic cavity from
the abdominal cavity.
• The muscular fibers originate around the circumference of the inferior
thorax and converge to a common insertion point of the central
tendon.
• The muscle slips according to their origins:
sternal: arises from two strips under the xiphoid process
costal: arise from the inner surfaces of the lower six costal cartilages and
adjoining ribs, interdigitating with the transversus abdominus muscles
lumbar: arise from the aponeurotic arches (lumbocostal arches) and from the
lumbar vertebrae (crura)

4. There are two paired
tendinous lumbocostal arches:
• medial lumbocostal arch (MAL): a
tendinous arch that covers psoas
major; attached to the L2 vertebral
body and in the front of the transverse
process of L1 and L2.
• lateral lumbocostal arch (LAL):
covers quadratus lumborum; attaches
medially to the L1 transverse process
and attaches laterally to the tip of the
12th rib.
Figure Drawing (view from below) shows the large central tendon, which is formed by
the transverse septum. The medial and lateral arcuate ligaments are thickened fascial
bands that cover the anterior psoas and quadratus lumborum muscles, respectively.
Note the crura and their attachments to upper lumbar vertebral bodies.

5. • The crura are tendinous
structures that blend with
the ALL :
right crus: arises from the anterior
surfaces of the bodies of L1-3
left crus: arises from the
corresponding portions of L1-2
• The medial margins of the two
crura pass forwards and medially
to meet in the midline & form an
arch in front of the aorta called
the MdAL.

6. • Hypertrophy or low position of
this MdAL can cause
compression of the celiac artery,
leading to epigastric pain and
weight loss (median arcuate
ligament syndrome) .

7. • All these muscles insert into the central tendon, a thin but strong
aponeurosis.
• It is situated immediately below and is fused to the pericardium.

8. Apertures: 3 major and some minor:
• venal caval hiatus
• esophageal hiatus
• aortic hiatus
• lesser apertures
• sternocostal foramina

10. • Blood supply
• costal margins: lower five intercostal arteries; subcostal arteries
• abdominal surface: inferior phrenic arteries

11. Innervation
• each phrenic nerve (C3-5)
supplies the ipsilateral
hemidiaphragm with motor
fibers
• lower intercostal nerves supply
proprioceptive fibers to the
margins

12. Development
from four main sources:
• septum transversum
• produces most of the central tendon and
contributes to the ventral mesentery in the gut
• cervical myotomes (3rd to 5th):
• infiltrates the septum transversum with muscle
cells
• carries their own nerve supply from these levels
explaining the C3,4,5 origin of the phrenic nerve
• pleuroperitoneal membrane
• mesodermal folds which connect the septum
transversum to the pericardioperitoneal canals
• separates the peritoneal and pleuropericardial
cavities
• esophageal mesentery Figure Development of the diaphragm. Schematic (view from below)
shows that the diaphragm develops by fusion of four structures: the
paired pleuroperitoneal folds, esophageal mesentery, transverse septum,
and muscular body wall. IVC = inferior vena cava.

13. Variant anatomy
• Scalloping or serrated appearance
• muscle slips
• Diaphragmatic hump and dromedary diaphragm
• accessory diaphragm

14. • Scalloping: Short curves, convex
upward; (predominantly on the right
side)
• Muscle slips: small curved lines,
concave upward (more common on
the right side): most commonly seen
in tall, thin patients and in those with
emphysema.

15. Diaphragm humps and dromedary diaphragm
• probably mild forms of eventration with
incomplete muscularisation of the
hemidiaphragm but no muscle defect.
• They arise anteriorly and are usually right-
sided, containing liver.
• CXR PA: hump appears as a shadow in the right
cardiophrenic angle and must be distinguished
from a fat pad, lipoma, pericardial cyst and
Morgagni hernia.
• CXR Lat: hump overlies the cardiac shadow
and should not be confused with middle lobe
consolidation.
• Dromedary diaphragm: more severe form of
diaphragm hump appearing as a double
contour on the PA view.

16. Accessory diaphragm
• rare condition
• asymptomatic and usually right sided.
• The hemithorax is partitioned by the accessory diaphragm running parallel to
the oblique fissure and resembling a thickened fissure.
• Associations: other congenital lesions of the lungs (s/a: anomalous venous
drainage and lobar hypoplasia).

17. CXR: level of diaphragm
• Flattening of the diaphragm is the most sensitive sign on chest
radiographs for the presence of hyperinflation of the lungs, usually
due to emphysema.
• The normal dome of each hemidiaphragm should rise at least 1.5 cm
above a line connecting the costophrenic angle and sternophrenic
angle.

18. • Elevated hemidiaphragms can result from many causes:
• above the diaphragm
• decreased lung volume
• atelectasis/collapse
• lobectomy/pneumonectomy
• pulmonary hypoplasia
• diaphragm
• phrenic nerve palsy
• diaphragmatic eventration
• below the diaphragm
• abdominal tumor, e.g. liver metastases or primary malignancy
• subphrenic abscess
• distended stomach or colon

19. Diaphragmatic Dysfunction
• can be classified as paralysis, weakness,
or eventration.
• Iinitially suggested by diaphragmatic
elevation at CXR.
• Elevation in paralysis or weakness:
entire hemidiaphragm,
(cf. elevation in eventration: only a
portion of a hemidiaphragm)
• In diaphragmatic dysfunction, the
impaired hemidiaphragm may be
thinned by atrophy of the muscle
Figure: Diaphragmatic atrophy due to polymyositis. Coronal CT image shows
thinning and elevation of both hemidiaphragms, findings that are more easily
appreciated on the left (arrow).

20. • Diaphragmatic dysfunction: unilateral or bilateral.
• Unilateral: often asymptomatic and discovered incidentally.
S/S: orthopnea or dyspnea on exertion, often more severe in patients with
underlying pulmonary disease
PFT: restrictive pattern (decreased FVC, FEV1)
• Bilateral: usu. symptomatic and may lead to ventilatory failure. Use of
the accessory muscles of respiration is there.

21. Paralysis and Weakness
• causes:
cervical spine trauma and
degeneration.
cervical spinal cord disease
(transverse myelitis, syrinx, and
tumor)
disease of the anterior horn cells
of the spinal cord (amyotrophic
lateral sclerosis, poliomyelitis, and
infection with West Nile virus)

22. Diaphragmatic dysfunction caused by transverse myelitis or leukemic infiltration of the cervical spinal
cord in a patient with leukemia and shortness of breath. (a) Coronal CT image shows elevation of the
left hemidiaphragm. (b) Sagittal T2-weighted MR image shows abnormal high signal intensity involving
the dorsal columns (arrows). The findings are indicative of transverse myelitis or leukemic infiltration as
the cause of phrenic nerve dysfunction.

23. Figure: Diaphragmatic paralysis caused by invasion of the phrenic nerve by non–small
cell lung carcinoma. Coronal CT image shows elevation of the right hemidiaphragm and
a right mediastinal mass (arrow).

24. Eventration
• involves only a segment of a hemidiaphragm, most commonly the
anteromedial portion of the left hemidiaphragm. (some authors say:
right more common)
• On radiographs, a portion of the hemidiaphragm is elevated while the
remaining portion is of normal height. At CT, there may be a sharp
transition at the edge of the eventration. Sometimes the edges are
undercut with ballooning above.

25. Bilateral eventration. (a, b) Posteroanterior (a) and lateral (b) radiographs show focal anterior elevation of the
right and left hemidiaphragms (arrows). (c) Coronal CT image shows focal elevation of both hemidiaphragms with
undercut edges (arrows) or a mushroom appearance. Although the mushroom appearance can also occur with
diaphragmatic hernia, the diaphragm in eventration is continuous.

26. Fig: Coronal (left) and 3D volume-rendered (right) CT images show
right hemidiaphragmatic eventration (arrows).

27. Mimics
• Diaphragmatic elevation can also be caused by other conditions:
normal exhalation.
Condition that increases intraabdominal pressure ( abdominal obesity,
ascites, and hepatosplenomegaly)
conditions that cause lung volume loss(atelectasis, lung resection, and
pulmonary fibrosis).

28. Fig: Diaphragmatic elevation secondary to pulmonary fibrosis. (a) Initial posteroanterior radiograph
shows elevation of both hemidiaphragms (arrows) owing to advanced pulmonary fibrosis. (b) On a
radiograph obtained after transplantation of the left lung, the left hemidiaphragm is lower but the right
hemidiaphragm remains elevated (arrow). This elevation should not be misinterpreted as indicative of
right phrenic nerve injury.

29. • In pleural thickening, the diaphragm may become tethered to the
chest wall, causing elevation and an abnormal diaphragmatic contour.
• Subpulmonic pleural effusion mimics diaphragmatic elevation, but
the relatively flat appearance and lateral peaking of the apparent
dome should suggest a subpulmonic effusion rather than elevation of
the hemidiaphragm.

30. Fig: Subpulmonic pleural effusion mimicking hemidiaphragmatic elevation. (a) Posteroanterior radiograph
shows an appearance that was initially interpreted as elevation of the right hemidiaphragm. Close
inspection reveals a lateral peak (arrow), a finding suggestive of a subpulmonic effusion. (b) Coronal
CT image shows a subpulmonic effusion (arrow). The right hemidiaphragm has a normal position.

31. Fluoroscopic Sniff Test
• Functional imaging allows further evaluation after diaphragmatic
elevation is recognized on a radiograph.
• simple to perform and the results are easy to interpret.

32. Technique
• Patient practiced twice - deep breathing and sniffing.
• PA vertical : center the x-ray beam at the level of the diaphragm and collimate
from the sides. However, we include the upper chest so that we can observe the
motion of the anterior chest wall. observe and record two or three quiet
(spontaneous and uninstructed) breaths and then two or three deep breaths and
finally two or three sniffs.
• Lateral position (with arms raised or folded on top of the head): repeat the
sequence of quiet breaths, deep breaths, and sniffs. Imaging in the lateral
position shows the motion of the posterior hemidiaphragms, which may move
differently from the anterior hemidiaphragms. It also shows the motion of the
sternum and anterior chest wall.
• With each breath and sniff, observe the direction of motion and the extent of
excursion of each hemidiaphragm relative to the contralateral hemidiaphragm
and rib

33. Normal Findings
• On quiet and deep inspiration, both hemidiaphragms move downward as the
anterior chest wall moves anteriorly Movie2.mp4, Movie3.mp4
• On deep inspiration, normal excursion is at least one rib interspace in adults (3-6
cm).
(The excursion may be somewhat asymmetric and there may be a slight delay or lag on one side, typically
the right. In the lateral projection, the excursion of the posterior part of the hemidiaphragm may be
greater than that of the anterior part, especially on the right.)
• On sniffing, both hemdiaphragms move downward.
( As on deep inspiration, there may be some asymmetry of excursion, there may be a slight lag on one
side, and the motion of the posterior aspect of the hemidiaphragm may be more vigorous than that of
the anterior part, especially on the right. If sniffing is very vigorous, there can even be momentary slight
paradoxical (upward) motion of the anterior hemidiaphragm, particularly the right.)

34. Abnormal Findings
• In paralysis of one hemidiaphragm: orthograde excursion is absent
and there may be paradoxical motion even on quiet and deep
inspiration. On sniffing, there is usually paradoxical motion.
Movie4.mp4, Movie5.mp4
• In paralysis of both hemidiaphragms, the two may move
paradoxically together if anterior chest wall motion is vigorous
enough. Movie6.mp4

35. • In weakness of one or both hemidiaphragms, excursion is reduced or delayed on
quiet and deep inspiration ( Movie7.mp4 Movie8.mp4 Movie9.mp4 ).
• If weakness is more severe, motion may be paradoxical on deep breathing and
even on quiet breathing, especially anteriorly. On sniffing, motion is usually
paradoxical.
• However, if there is any orthograde motion on quiet or deep inspiration, then the
hemidiaphragm is merely weak, but not paralyzed.

36. • Eventration of the hemidiaphragm is a special case of weakness in which only a
segment of the hemidiaphragm (typically the anterior aspect on the right) moves
abnormally.
• excursion of the affected segment is reduced on quiet and deep inspiration and
may be paradoxical on sniffing. The posterior aspect of the hemidiaphragm
retains normal motion. This can lead to a rocking motion of the hemidiaphragm
on the lateral view, with the anterior part moving up as the posterior part moves
down. (Movie10.mp4 )

37. US Imaging
• Diaphragmatic US has the benefit of portability and is often considered the
preferred examination in children and young adults owing to the absence of
ionizing radiation.
• At US, the diaphragm appears as a thick echogenic line. M-mode US may be used
to measure the direction of diaphragmatic motion and the amplitude of
excursion.

38. Thickness
• High frequency transducer 7-18 MHz
• Anterior axillary line
• Sagittal image at the intercostal space
between the 7th/8th , 8th /9th ribs
• Visualization of both the pleural and
peritoneal membranes at all times while
imaging the diaphragm for thickness
measurements.
• ‘Zone of apposition’

39. • Average thickness of the diaphragm : 2.2–2.8 mm
• Thickness <2 mm, measured at the end of expiration –indicates
diaphragm atrophy
Change in Thickness
• A chronically paralyzed diaphragm is thin, atrophic, and does not
thicken during inspiration
DTF= (T end-inspiration – T end-expiration) /T end-expiration
• Diaphragm thickening <20% is proposed to be consistent with
paralysis

40. Excursion
• Lower frequency, ideally curvilinear,
transducer (2 to 6 MHz)
• Anterior subcostal region
• Transducer is directed medially, cranially,
and dorsally, so that the ultrasound beam
reaches the posterior third of the right
diaphragm
• B mode to visualize , M mode to measure

41. • the concept behind this examination is identical to that of the
fluoroscopic sniff test.
• There is similar excursion of the two hemidiaphragms, although the
motion of the left hemidiaphragm may be slightly greater than that of
the right hemidiaphragm ( Movie11.mp4 ).
• A paralyzed hemidiaphragm will demonstrate no orthograde
movement with quiet breathing and may have paradoxical movement
( Movie12.mp4 )

42. • Normal range of motion from the resting expiratory position to full
inspiration in adults: 1.9 to 9 cm (avg 3-6 cm)
• Excursion >2.5 cm in adults cut off for excluding severe diaphragm
dysfunction
• Excursion < 4 mm, and a difference >50% between the excursion of
one hemidiaphragm compared to the other - diaphragmatic palsy.

43. Dynamic MR
• performance of dynamic MR imaging for evaluation of diaphragmatic
function has also been described.
• Spoiled gradient-echo and cine balanced steady-state free-precession
sequences may be used.
• largely limited by high costs.
(Not widely used.)

44. Diaphragmatic rupture
• Traumatic diaphragmatic injuries occur in 0.8%–8% of patients who
sustain blunt trauma. Up to 90%: from blunt trauma occur in young
men after motor vehicle accidents
• Both bilateral tears and extension of tears into the central tendon are
uncommon. reported in 2%–6% pt with diaphragmatic injury.
• Mechanisms of injuries: lateral impact, shears the diaphragm &
direct frontal impact

45. • Most ruptures are >10 cm and occur
at the posterolateral aspect between
the lumbar and intercostal
attachments and spread in a radial
direction
• Penetrating injuries such as gunshot
wounds or stab injuries: more
random.
Sites of injuries. Drawing shows radial (A), transverse (B), and central (C)
ruptures and a peripheral detachment (D). Radial tears appear to be the most
frequently found injury at surgery, whereas peripheral detachments are the least
frequent

46. ASSOSCIATED INJURIES
• Common : pelvic fractures (40%–55%), splenic injuries (60%), and
renal injuries
• Liver injuries, which are more frequently associated with right than
with left diaphragmatic tears
• Thoracic injuries : pneumohemothoraces and rib fractures are seen in
90% of patients. Aortic injuries are reported in 5% of patients

47. DIAPHRAGM INJURY (IMAGING)
A. Chest X-ray :
(a) intrathoracic herniation of a hollow
viscus (stomach, colon, small bowel)
with or without focal constriction of
the viscus at the site of the tear (collar
sign)
(b) visualization of NG tube above the
hemidiaphragm on the left side
• Findings suggestive of
hemidiaphragmatic rupture:
elevation, distortion or obliteration of
the outline, and contralateral shift of
the mediastinum

48. B. CT CHEST: Helical CT has overall sensitivity of 71%:
1. Direct discontinuity of the hemidiaphragm: Sn 73%, Sp 90%.
2. Intrathoracic herniation of abdominal contents: Sn 55%, Sp 100%.
3. collar sign: Sn 63%
4. dependent viscera sign: Sn: 100% (left sided); 83% (right-sided)
(when a patient with a ruptured diaphragm lies supine at CT examination, the herniated viscera
(bowel or solid organs) are no longer supported posteriorly by the injured diaphragm and fall to
a dependent position against the posterior ribs)

49. Diaphragmatic tumours
• are rare.
• may appear as smooth or lobulated masses and need to be differentiated from
lung and liver masses, hernias and diaphragm humps. CT is the most helpful
investigation.
• may be divided into:
 primary benign neoplasms
 primary malignant neoplasms
 secondary malignant neoplasms
 cysts
 inflammatory lesions
 endometriosis.

50. PRIMARY BENIGN NEOPLASMS
• from any of the normal tissue
components . Eg: Lipomas, fibromas,
angiofibromas, neurofibromas and
neurilemmomas
• Diagnosed mostly post mortem
biopsy.
• X-ray appearance as irregularity in
diaphragm

51. PRIMARY MALIGNANT NEOPLASMS
• Majority are fibrous tissue origin. (Eg; fibrosarcoma,
fibromyosarcoma, fibroangio-endothelioma)
• mixed cell sarcoma, myosarcoma, rhabdomyosarcoma
(Sarcomas commonly present with a pleural effusion.)

52. SECONADARY MALIGNANT NEOPLASMS
• Contigious spread: liver, lungs (including pleura), stomach, kidneys,
adrenals
• Others: chondrosarcoma , Hodgkin’s disease
(Hematogeneous mets are rare.)
• Resembles benign tumours radiogrpahically.

53. Diaphragmatic hernias
Congenital
• two main types that usually occur on the left side (80%)
Bochdalek hernia: most common (95%), located posterolaterally and
usually present in infancy.
Morgagni hernia: smaller, anterior and presents later in life, through
the sternocostal angles.
Acquired
• variety of etiologies:
traumatic diaphragmatic rupture through either penetrating injury (65%) or blunt
trauma (35%)
hiatus hernia
iatrogenic

54. BOCHDALEK HERNIA
• Posterior aspect
• most frequently left sided.
• defect in the posterior attachment of the
diaphragm when there is a failure of
pleuroperitoneal membrane closure.
• Content: omentum, fat, spleen, kidney and
bowel
• Ipsilateral lung: invariably hypoplastic with
deviation of the mediastinum away from the
side of the hernia
Fig: Frontal radiograph of the chest in a newborn shows herniation of bowel loops
into the left hemithorax with displacement of the heart to the right, findings
consistent with left Bochdalek hernia.
The nasogastric tube (arrows) in the left hemithorax indicates the intrathoracic
stomach.

55. MORGAGNI’S HERNIA
• Anterior defect of the diaphragm
• Retrosternal, or parasternal hernia
• herniation through the foramina of
Morgagni
• Contents : the liver, spleen, and
omentum
• D/D:
Thymoma, Rt middle lobe collapse,
hydatid cyst, fibrous tumor of the pleura
Cardiophrenic angle lesions:
lymphadenopathy; pericardial cyst ;
pericardial lipomatosis
Morgagni hernia in a 2-year-old child. Lateral chest radiograph shows herniation of a
bowel loop (arrows) in a classic location through an anteromedial defect.

56. HIATUS HERNIA
• herniation of stomach through the
oesophageal hiatus of the diaphragm
• Types
1. Sliding 2. roling (para-
oesophageal)
• Content : always Stomach ; rarely with
bowel loops (if the defect is large enough)
• D/D: Lung abscess (Retrocardiac),
Empyema , epiphrenic-oesophageal
diverticulum

57. Summary
• The diaphragm is the primary muscle of ventilation.
• Dysfunction of the diaphragm is an underappreciated cause of
respiratory difficulties and may be due to a wide variety of entities,
including surgery, trauma, tumor, and infection. Diaphragmatic
disease usually manifests as elevation.
• Functional imaging with fluoroscopy (or US or MR imaging) is a simple
and effective way to diagnose diaphragmatic dysfunction.

58. Thank You!

59. References
1. Imaging of the Diaphragm: Anatomy and Function by Laura K.
Nason et al; RadioGraphics Volume 32, Issue 2 Mar 1, 2012
https://doi.org/10.1148/rg.322115127
2. Textbook of Radiology and Imaging by David Sutton 7th/e
3. Chest Sonography by Gebhard Mathis 4th Edition; 2016
4. BD Chaurasia’s Textbook of Anatomy Vol 1 (slides 7, 8)