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IMAGING & ITS ROLE IN FEMALE GENITAL CANCER

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Role of CT scan in carcinoma cervix
Contouring Guidelines for Carcinoma Cervix (3DCRT/IMRT)
Normal Tissue Delineation (RTOG

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IMAGING & ITS ROLE IN FEMALE GENITAL CANCER

  1. 1. IMAGING & ITS ROLE IN FEMALE GENITAL ORGANS
  2. 2. Radiological imaging. • XRAY • ULTRASOUND • CT SCAN • MRI • PET CT SCAN
  3. 3. X-ray female pelvis
  4. 4. Field borders: AP-PA fields Superior border • At the L4-5 space to include external & internal iliac L.N. • extended to the L3-4 space if common iliac nodal coverage is indicated • . extended to the T11-12 space if paraaortic coverage is indicated Inferior border • at inferior border of the obturator foramen. • For vaginal involvement:3cm below the lower most extent of disease Lateral borders • 1.5 - 2cm margin on the widest portion of pelvic brim
  5. 5. Field borders : lateral field Anterior margin • vertical line to the anterior edge of pubic symphysis to cover external iliac lymph nodes Posterior margin • at S2 – S3 junction • extend to sacral hollow in patients with advanced tumours to cover uterosacral ligaments, cardinal ligaments & presacral lymph nodes • Superior & inferior margins • same as that for AP/PA Fields
  6. 6. Field borders: AP-PA fields Field borders : lateral field
  7. 7. ULTRASOUND ABDOMEN & PELVIS • Routine Use: • to detect liver Mets, ascites or abdominal lymphadenopathy. • Give information about the status of kidneys & ureter (HUN if any) • Can tell about any associated benign pelvic pathology, uterine collections etc • US has limited role in evaluating the size and local regional extent of the tumour • in early stages :USG may fail to detect any malignancy • Eventually, with disease progression, the tumour mass may appear as a hypoechoic or isoechoic region with undefined margins.
  8. 8. CT scan. • CT Scan: CT is the imaging modality that is most commonly used in clinical practice to evaluate the extent of spread malignancy • The oral, rectal, or intravenous administration of contrast material is necessary for optimal CT evaluation (unless a contraindication exists). • CT provides diagnostic information about the • the primary tumour. • enlarged lymph nodes, and • presence of metastases,
  9. 9. Role of CT scan in carcinoma cervix • CT can demonstrate pelvic side wall extension, • ureteral obstruction, • advanced bladder and rectal invasion, • adenopathy, and • extrapelvic spread of disease • CT can also be used to guide biopsy of enlarged nodes, plan radiation therapy ports, and monitor patients for tumor recurrence
  10. 10. • The limitations of CT have been lack of consistent visualization of the primary tumor and inaccuracies in detection of parametrial invasion • For identification of stromal and parametrial invasion, MR imaging has been shown to be superior to CT Role of CT scan in carcinoma cervix
  11. 11. MRI • MRI is frequently used now for the initial assessment of the tumour and local extension • Advantages of MRI over CT scan is • better soft tissue contrast • superior imaging resolution Currently MRI Is The Investigation Of Choice For Staging Gynaecological Malignancy
  12. 12. Positron emission tomography (PET) • Limited role • Can detect early metastatic disease • some value relative to conventional imaging methods for the detection of nodal metastatic disease and recurrent cervical cancer,
  13. 13. NORMAL RADIOLOGICAL ANATOMY
  14. 14. 1. Aorta. The aorta continues inferiorly into the lower abdomen and pelvis, bifurcating into the common iliac arteries in front of the 4th lumbar vertebra (2) Inferior Vena Cava The inferior vena cava is a large vein that returns blood from the blood in the lower part of the body. It is a reservoir for the common iliac, lumbar, right gonadal, renal, right adrenal, and hepatic veins. (3) Ureter The ureter is a tubular structure that receives urine from the kidney and delivers it to the urinary bladder. (4) Left Kidney The left kidney is usually slightly higher than the right kidney. The left renal vein is long and crosses the aorta anteriorly to reach the left kidney. CONTRAST ENHANCED CT SCAN ABDOMEN AT LEVEL OF L2 VERTEBRA
  15. 15. (6) Cecum The cecum is the first part of the large intestine. It is about 7 cm. in length. It is located in the right lower quadrant, below the ascending colon. (7) Descending Colon (5) Small Bowel The small intestine is the longest part of the gastrointestinal tract, usually measuring 6-7 meters. On this cross sectional image, the small bowel is identified by white coloration due to filling of the barium contrast agent. CONTRAST ENHANCED CT SCAN ABDOMEN AT LEVEL OF L2 VERTEBRA
  16. 16. (8) Psoas Muscle This is a muscle that runs from the transverse processes of the lumbar vertebrae to attach to the lesser trochanter of the femur (9) Erector Spinae Muscle This is a large muscle located on each side of the spinal column (10) Rectus Abdominus Muscle This muscle is considered the principle muscle of the anterior abdominal wall and runs vertically from the xiphoid process to the pubic symphysis and pubic crest (11) External Oblique Muscle (12) Internal Oblique Muscle (13) Tranversus Abdominus Muscle (14) Quadratus Lumborum Muscle (15) Vertebra (Body) (16) Vertebra (Spinous Process) CONTRAST ENHANCED CT SCAN ABDOMEN AT LEVEL OF L4 VERTEBRA
  17. 17. (17) Common Iliac Arteries These vessels are the continuation of the abdominal aorta after it bifurcates in the abdomen. The right and left common iliacs then give rise to the internal and external iliacs in the pelvis. (17a) Common Iliac Veins The common iliac veins converge to form the inferior vena cava. The two veins are located posterior and to the right of their counterpart common iliac arteries. The two common iliac veins are formed by the internal and external iliac veins which drain the blood from the pelvis and lower extremity. (19) External Iliac Vessels This is one of the two bifurcations of the common iliac as it descends into the pelvis. CONTRAST ENHANCED CT SCAN ABDOMEN AT LEVEL OF L4 VERTEBRA
  18. 18. (20) Common Femoral Artery and Vein The common femoral artery is a continuation of the external iliac vessels below the inguinal ligament. CONTRAST ENHANCED CT SCAN PELVIS
  19. 19. (23) Iliacus Muscle This is muscle is located lateral to the psoas major muscle and attaches to the body of the femur below the lesser trochanter. It originates from the iliac crest, iliac fossa and ala of the sacrum. (24) Gluteus Maximus Muscle (25) Gluteus Medius Muscle (26) Gluteus Minimus Muscle (27) Sacrum This bone if formed by the five sacral vertebral that are fused together to form a wedged shape bone that functions to supports the pelvis
  20. 20. (28) Urinary Bladder This is a hollow muscle which functions to hold urine. In adults it is located posterior and superior to the pubic bones An adult bladder is located in the pelvis but it extends into the abdomen when it is full of urine. (30) Rectum This is the end and last part of the colon. It is located between the sigmoid colon and the anus. In females the rectum is located posterior to the vagina and uterus.. (34) Piriformis Muscle This pear shaped muscle is located in the posterior pelvis. It originates from the 2nd through 4th sacral segments and inserts on the greater trochanter of the femur (29) Sigmoid Colon This is the end of the intestine located between the descending colon and the rectum.
  21. 21. (42) Symphysis Pubis This is a tough cartilage that joins the two bodies of the two pubic bones. (36) Femoral Head The femoral head is the part of the femur that fits into the acetabulum of the pelvis.
  22. 22. T1-weighted, axial view. Image 1. 1, Rectus abdominis m. 2, external iliac vein 3, external iliac artery 4, right ovary 5, uterus 6, left ovary 7,ilium 8, rectum 9, sacrum
  23. 23. MRI of the female pelvis: T1-weighted, axial view. Image 1, Rectus abdominis m 2, external iliac vein 3, external iliac artery 4, obturator internus m. 5, right ovary 6, endometrium 7, junctional zone 8, myometrium 9, left ovary 10, rectum
  24. 24. MRI of the female pelvis: T1-weighted, axial view. Image 1, Rectus abdominis m. 2, external iliac vein 3, external iliac artery 4, obturator internus m. 5, head of the femur 6, endocervical canal 7, rectum 8, ischiorectal fossa 9, gluteus maximus 10, uterus
  25. 25. MRI of the female pelvis: T1-weighted, axial view. Image 1, Rectus abdominis m. 2, femoral vein 3, femoral artery 4, pectineus muscle 5, obturator internus m. 6,bladder 7, vagina 8, anal canal 9, head of the femur 10, ischiorectal fossa 11, gluteus maximus m.
  26. 26. MRI of the female pelvis: T1-weighted, coronal view. 1, Rectus abdominis m. 2, Bladder 3, Pubis 4, fundus uterus 5, corpus uterus 6, endocervical canal 7,rectum 8, Sacrum
  27. 27. MRI of the female pelvis: T1-weighted, coronal view. 1, Rectus abdominis m. 2, Pubis 3, Bladder 4, urethra 5, uterus 6, endometrium 7, vagina 8, rectum 9,sacrum
  28. 28. MRI anatomy of the cervix is best delineated on T2W image [Figure 1] as it outlines the four major zones of cervix. From center to periphery, these are high signal intensity endocervical canal, intermediate signal intensity plicae palmatae, low signal intensity fibrous stroma, and intermediate signal intensity outer smooth muscle
  29. 29. Stage II is considered when the tumor extends beyond the cervix. Involvement of the upper two-third of the vagina is seen as segmental loss of the normally seen T2-hypointense vaginal wall and is staged as IIA [Figure 4].
  30. 30. In stage IIB, the tumor disrupts the normally seen hypointense peripheral stroma on T2W images and extends in the parametrium [Figure 5]
  31. 31. Stage III is defined as tumor extension to the lower third of the vagina or lateral pelvic wall with associated hydronephrosis. Involvement of lower third of the vagina without extension to pelvic wall is IIIA [Figure 6].
  32. 32. Stage IIIB is considered when the tumor is less than 3 mm from the side wall, causes hydroureter, infiltrates the obturator internus, pyriformis, and levator ani muscles, encases the iliac vessels, and destroys the pelvic bones [Figure 7)
  33. 33. Presence of bladder or rectal mucosa involvement or distant metastasis upgrades the tumor to stage IV. In stage IVA, bladder and rectal invasion is suggested by the presence of focal or diffuse disruption of the normally seen T2- low signal intensity wall, irregular or nodular wall, and presence of an intraluminal mass [Figure 8]. Figure 8(A-C): Squamous cell carcinoma in two different patients (stage IVA). Sagittal T2W image shows a large mass arising from the cervix and involving the uterine myometrium (white arrow in A) with invasion in the rectum demonstrated as loss of T2-low signal intensity rectal wall (black arrow in A). Also note the infiltration in posterior bladder wall (white arrow-head in A), better seen in the second patient on T2 and post-gadolinium image (white arrow heads in B and C)
  34. 34. Bulbous edema sign, which is hyperintense thickening of the bladder mucosa on T2W images, is an indirect sign of invasion and should be evaluated with care for associated tumor nodule [Figure 9].
  35. 35. Vulvar squamous cell carcinoma in 53-year-old woman presenting with nonhealing ulcer. Labeled structures are uterus (ut), bladder (b), levator ani (l), pubic bone (p), urethra (u), vagina (v), anus (a), obturator internus (o), femoral vessels (f), and rectum (r). Sagittal fast spin-echo T2 MR image shows 4-cm skin-based mildly hyperintense mass (arrow) in left vulva. Arrowheads indicate deep margin of mass. Deep margin of mass (arrowheads) is approximately 1 cm from underlying pubic bone, which predicts surgical margin not sufficiently clear of tumor. A left inguinal node (thick arrow) shows features of tumor involvement, being abnormally enlarged (2.3 cm) on MRI.
  36. 36. Vaginal squamous cell carcinoma in 56-year-old woman presenting with postmenopausal bleeding. Labeled structures are bladder (b), urethra (u), vagina (v), and levator ani (l). Sagittal fast spin-echo T2 (A) and axial fat- saturated gadolinium-enhanced T1 (B) MR images show mildly hyperintense infiltrating homogeneously enhancing mass (thin arrows) extending from posterior vaginal wall into rectum. On T2-weighted image, tumor obliterates hypointense muscles of anal sphincter and anterior rectal wall and markedly hyperintense rectal mucosa. Inguinal nodes (thick arrows, B) bilaterally are enlarged (2–5 cm) and show central hypoenhancement of necrosis, all features indicating tumor involvement.
  37. 37. Contouring Guidelines for Carcinoma Cervix (3DCRT/IMRT)
  38. 38. Target Volume delineation  For definitive treatment of carcinoma cervix with conformal radiation techniques, accurate target delineation is vitally important,  Various guidelines for CTV delineation are published in the literature yet a consensus definition of clinical target volume (CTV) remains variable  Clinical judgement remains the most important aspect of determining the target volumes
  39. 39. Contouring Several contouring guidelines available for CTV Taylor et al pelvic nodal delineation (CT based) Toita et al for CTV delineation in intact cervix EBRT (CT based) Lim et al for CTV delineation in intact cervix IMRT (MRI based) Small et al for CTV delineation in post operative IMRT (CT based) PGI literature review & guidelines for delineation of CTV for intact carcinoma cervix (CT based) Guidelines for organ at risk Pelvic Normal Tissue Contouring Guidelines for Radiation Therapy: A Radiation Therapy Oncology Group Consensus Panel Atlas (CT based)
  40. 40.  The aim of the article was to review the guidelines for CTV delineation published in the literature and to present the guidelines practiced at their institute  6 articles : 2 articles from Taylor et al and Toita et al and 1 from Small et al., Lim et al., were reviewed  The CTV in cervical cancer consists of the CTV nodal and CTV primary.  CTV nodal consists of common iliac, external iliac, internal iliac, pre-sacral and obturator group of lymph nodes  CTV primary consists of the gross tumor volume, uterine cervix, uterine corpus, parametrium, upper third of vagina and uterosacral ligaments.   This was the first report to provide the complete set of guidelines for delineating both the CTV primary and CTV nodal in combination for intact cervix
  41. 41. CTV nodal (CTV 1) • CTV N includes involved nodes and relevant draining nodal groups (common iliac, external iliac, internal iliac, obturator and pre sacral lymph nodes). • Pelvic LN CTV is contoured in accordance with the latest Taylor’s guidelines with some modifications • VESSELS: Start contouring iliac vessels from aortic bifurcation down till the appearance of femoral head. • Uniformly, pelvic blood vessels are given a margin of 7mm. The upper border is maintained at aortic bifurcation. • The contour is extended around common iliac vessels posteriorly and laterally so as to include connective tissue between iliopsoas muscles and lateral surface of vertebral body. • All visible nodes (contoured as GTV node) are given a margin of 10mm to create CTV node. • Muscle and bone are excluded from CTV N.
  42. 42. Common iliac nodes The contour is extended around common iliac vessels posteriorly and laterally so as to include connective tissue between iliopsoas muscles and lateral surface of vertebral body.
  43. 43. External iliac :7 mm margin around vessels.  Taylor recommends contouring external iliac nodes around external iliac vessels until they pass through inguinal ligament. And further recommend extending the external iliac contours antero-laterally along the iliopsoas by 10 mm (a total of 17mm from the vessel) for covering lateral external iliac group of LNs.  Toita however exactly defines the caudal margin of external iliac region at the level of superior border of femoral head, as beyond this, external iliac vessels pass through inguinal ligament and continue as femoral vessels.  Following these guidelines, large area of femoral head and neck irradiation can be avoided
  44. 44. • Both Toita and Small et al. also do not follow this anterolateral extension. • Also, out of the three groups of LNs, the medial groups of nodes are the one which are considered to be the main channel of drainage, collecting lymph from uterine cervix and upper vagina. • Hence current guidelines ; do not follow and recommend such anterolateral extension to external iliac region.
  45. 45.  The caudal margin of internal iliac vessels is defined at ischial spine  The posterior margin of internal iliac lymph node region is defined at wing of sacrum or anterior edge of piriformis muscle.  The lateral margin of internal iliac lymph node region is defined by iliac bone, psoas muscle or medial edge of Iliacus muscle in cranial slices and obturator internus muscle or piriformis muscle in caudal slices  Extend lateral borders to pelvic side wall Internal iliac: 7 mm margin around vessels.
  46. 46. • To cover obturator nodes, a strip 17 mm wide is created medial to the pelvic sidewall, by joining the contour of external iliac vessels with internal iliac vessels. Contouring of obturator nodes with 17 mm brush is continued lower down along pelvic side wall, till superior part of obturator foramen • From anatomical knowledge of the course of obturator vessels within the pelvis,[36] caudal border of obturator nodes is defined at upper level of obturator foramen, since obturator artery leaves and obturator vein enters pelvis at this level. Toita defines the caudal extent of obturator lymph node till superior border of obturator foramen Obturator Nodes
  47. 47. PRESACRAL NODES • Pre-sacral region is covered by connecting the volumes on each side of pelvis with a 10-mm strip over the anterior sacrum starting from aortic bifurcation till S2-S3 junction. • Sacral foramina are not included in CTV N
  48. 48. • The caudal margin of internal iliac nodes is at the level of Ischial spine. • The caudal margin of external iliac nodes is till the appearance of femoral head. • The caudal extent of obturator lymph node is till superior border of obturator foramen
  49. 49. • All guidelines recommended excluding bones and muscles from CTV 1. • However, bowel was not routinely excluded by any of the guideline except the guideline by Small et al.[13] • This is because the later guidelines are for post operative cases of carcinoma cervix and endometrium, where bowel loops fall into pelvis after surgery. • So they excluded bowel loops from CTV 1 to decrease normal tissue toxicity. • All other guidelines also do not exclude bladder and bowel from the nodal contour, due to the daily changes in their shape and position.
  50. 50. CTV primary (CTV 2) • CTV Primary (CTV-P) includes GTV Primary, Uterine Cervix, Uterine Corpus, Parametrium, Vagina and Ovaries • UTERUS: The uterine corpus, entire cervix and the vagina are contoured along with the gross disease (GTV primary) as a single structure uterus (CTV 2)
  51. 51. Components of CTV The group consensus was that entire uterus should be included in the CTV because: • Uterus & cervix are embryologically one unit with interconnected lymphatics and no clear separating fascial plane • Second, determination of myometrial invasion can be difficult • uterine recurrences have been reported (2%), but exact location of these recurrences(fundal vs. corpus) have not been stated
  52. 52. • VAGINA: paravaginal tissue is included along with the vaginal wall. A vaginal marker is placed at the lower extent of vaginal disease while taking CT and as per RTOG guidelines: • Minimal or no vaginal wall involvement: The contouring is stopped few slices above the lower border of obturator foramen, so that when 1.5 cm ITV (internal target volume) margin is given over the uterus, the lower border does not extend beyond the lower border of obturator foramen. • Upper vaginal involvement: Upper two-thirds • Extensive vaginal involvement: Entire vagina CTV primary (CTV 2)
  53. 53. PARAMETRIUM (CTV 3) To delineate the parametrium , connective tissue extending from the cervix to the pelvic wall are included, along with the visible linear structures that run laterally (e.g. vessels, nerves and fibrous structures) • Cranial border : defined at the level where the true pelvis begins. Contours should stop once loops of bowel are seen next to the uterus (Lim/Toita etal.) • Anteriorly: contouring is done up to the level of posterior border of bladder in the central region, while, in periphery it extends till the anterior end of lateral pelvic bony wall. • Posteriorly: parametrium is contoured only till the anterior part (semi-circular)of mesorectal fascia. In case of significant parametrial invasion(IIIB)/uterosacral ligament involvement, include entire mesorectum.(Lim et al.(RTOG)/PGI Guidelines). • Laterally, the parametrium is contoured till the lateral pelvic wall, upto the medial edge of internal obturator muscle. • Caudal border of parametrium is taken at the pelvic floor
  54. 54. 2 f shows parametrial contouring for cervix cancer stage II B Cranial border : defined at the level where the true pelvis begins. Contours should stop once loops of bowel are seen next to the uterus Anteriorly: contouring is done up to the level of posterior border of bladder in the central region, while, in periphery it extends till the anterior end of lateral pelvic bony wall Posteriorly: parametrium is contoured only till the anterior part (semi-circular)of mesorectal fascia
  55. 55. In case of significant parametrial invasion(IIIB)/uterosacral ligament involvement, include entire mesorectum 2 g shows parametrial contouring for bulky stage III B,
  56. 56. Laterally, the parametrium is contoured till the lateral pelvic wall, upto the medial edge of internal obturator muscle. Caudal border of parametrium is taken at the pelvic floor
  57. 57. The CTV primary finally includes the uterus (CTV 2) and the parametrium (CTV 3). Ovaries visible on CT are included within the CTV primary
  58. 58. Total CTV: CTV N(CTV1) and the CTV primary (CTV2 & CTV 3) are combined and named as total CTV PTV Toatal: 10 mm over total CTV to account for set up errors ITV Margin: The uterine motion is accounted for by giving an ITV margin on the uterus…An asymmetrical margin with ITV expansion of 15 mm antero- posteriorly, 15mm supero- inferiorly and 7 mm laterally, is taken from the uterus (CTV 2) Purple: uterus Blue:ITV Green:CTV Total Yellow:PTV total
  59. 59. • Final PTV (red): The ITV margin given over CTV 2 for uterine motion is added to the total PTV and this is taken as the total target volume (final PTV) to be treated • Purple: uterus • Blue:ITV • Green:CTV Total • Yellow:PTV total • Red: PTV Final
  60. 60. Normal Tissue Delineation (RTOG) • Bowel: The small and large bowel can be contoured together as a Bowel-Bag. • Inferiorly, the bowel bag should begin with the first small or large bowel loop or above the ano-rectum, whichever is most inferior. • The contours should end 1 cm. above the PTV . • Ano-Rectum: Ano-Rectum should be contoured from the level of the anus to the sigmoid flexure. It should extend from the anal verge (marked by a radiopaque marker at simulation) to superiorly where it loses its round shape in the axial plane and connects anteriorly with the sigmoid. • Bladder: Contoured inferiorly from its base, and superiorly to the dome. • Femoral Heads:The ball of the femur, trochanters, and proximal shaft to the level of the bottom of ischial tuberosities Gay HA, Barthold HJ, O′Meara E, Bosch WR, El Naqa I, Al-Lozi R, et al. Pelvic normal tissue contouring guidelines for radiation therapy: A Radiation Therapy Oncology Group consensus panel atlas. Int J Radiat Oncol Biol Phys 2012;83:e353-62.

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