Imaging assessment in Gynaecology Flashcards
What imaging methods are used in obstetrics and gynaecology?
- Ultrasound
- CT
- MRI
- X-ray screening fluoroscopy - e.g. hysterosalpingograms (HSG)
- Functional imaging- PET CT
What are the indications for using radiology in obs & gynae?
- Diagnosis of pelvic pain – cause?
- Assessment of pelvic masses
- Investigation of abnormal menstrual bleeding
- Assessment of patients with post-menopausal bleeding (in Tayside, these patients tend be scanned by the gynaecology team at the PMB clinic)
- Investigation of infertility (these patients may also undergo MR scanning of the pituitary)
- Interventional radiology – fallopian tube recanalisation, uterine artery embolisation etc
Why is ultrasound used so commonly?
Cheap
No ionising radiation
Very good definition of different pelvic organs
Can be used in clinic as an adjunct to pelvic examination
What are the two main US techniques?
Transabdominal: standard general abdominal US transducer
Transvaginal: dedicated endocavity high-frequency transducer
How is transabdominal ultrasound performed?
Pelvic organs are scanned thorugh the anterior abdominal wall
Why should a brief assessment of the abdomen be performed before transabdominal ultrasound?
- to ensure that there is no hydronephrosis
- to detect early ascites
- to ensure that the pelvic abnormality is not secondary to upper abdominal pathology
Why must a patient have a full bladder for a transabdominal ultrasound?
The urine-distended bladder acts as an acoustic window
A distended bladder displaces gas-filled bowel loops out of the pelvis (bowel gas scatters the US beam and degrades image quality)
What are the advantages of transabdominal ultrasound?
- safe
- readily available
- no ionising radiation and therefore ideal for children and women of reproductive age
What are the disadvantages of transabdominal ultrasound?
- difficult to obtain good images in obese patients or when there is distension of the bowel
- operator dependant
- can’t get the same images every time- cant be used for assessing response to cancer treatment
What are the advantages of transvaginal ultrasound scanning?
Excellent depiction of the pelvic organs
What are the disadvantages of transvaginal scanning?
- More invasive procedure
- Not suitable for indivuduals who have not been sexually active
- Can sometimes not depict the full extent of pelvic masses
What is often used as a second-line investigation after ultrasound in patients presenting with acute abdominal pain?
CT scaninng
What can CT scanning be used for?
- assess post surgical complications
- small bowel obstruction secondary to adhesions
- post-operative collections/abscesses
- staging of gynaecological malignancy, especially ovarian and endometrial cancers
- assessing response to treatment in patients after chemotherapy +/- radiotherapy
What are the advantages of CT scanning?
- quick
- the entire chest and abdomen can be assessed on one scan
- modern multiple detector row (multislice) scanners
What are the disadvantages of CT scanning?
- high radiation dose (160 chest x-rays) with a significant dose to ovaries
- doesn’t provide optimal depiction of different pelvic organs
MRI scanning uses what rather than ionising radiation?
Radiofrequency energy
What are the advantages of MRI?
- provides excellent depiction of pelvic organs
- NO ionising radiaiton
- can give some idea about the composition of soft tissue masses- fluid, fat, blood
What are the disadvantages of MRI?
- time consuming
- poor depiction of lung parenchyma- a CT scan should be performed if there is query about pulmonary metastases
- not tolerated if patents have claustrophobia
- contra-indicated in patients with;
- pacemakers
- artificial metallic heart valves
- nerve stimulators
- cochlear implants
What are the uses of MRI in gynaecology patients?
- cancer staging- especially cervical
- evaluation and characterisation of adnexal and uterine masses, where pelvic US or other imaging techniques havent provided a diagnosis
- evaluation of patients with sub-fertility- are there contributory anatomical variations
- MR of pituitary glands is performed in patients with suspected prolactinoma
Why can endometriosis be diagnosed on MRI scans?
As deposits contain altered blood and haemoglobin degradation products. These degradation products cause characteristic MR signal changes.
Altered blood returns high-signal on T1 weighted sequency (looks white on scan) whereas it returns lower signal on T2 sequences (looks grey)
What is contained in a dermoid cyst?
Tissue derived from ectoderm, mesoderm and endoderm.
There can be a mixture of tissue but mostly fat
What is hysterosalingography?
X-ray screening procedure- real-time imaging for assessment of tubal patency in patients with infertility
can also assess outline of uterine cavity
How long dues hysterosalpingography take and how is it done?
Usually completed in 3-5 minutes
Cervix is cannulated and radiopaque contrast instilled to fill the uterine cavity- just before the contrast a scout ‘control film’ is obtained
Once instilled a series of images are captured as the contrast fills cavity then spills into peritoneal cavity
How does ovarian cancer disseminate?
By peritoneal spread
In ovarian cancer;
Ascites, _____ and ________ nodules are common
Sub-________ deposits and deposits on the surface of the _____ are also seen.
Ascites, omental and peritoneal nodules are common
Sub-diaphragmatic deposits and deposits on the surface of the liver are also seen.
What do pleuro-peritoneal communications result in?
Malignant pleural effusions can result from spread of disease via pleuro-peritoneal communications
Who tends to get lymph node, lung and hepatic metastases of ovarian cancer?
In patients in whom the disease behaviour has been modulated by chemotherapy or in cancers with the BRCA1 mutation
how is the initial diagnosis of ovarian cancer made?
By ultrasound (ovarian masses)
What is used for radiological staging of ovarian cancer?
CT scanning
What must be determined when staging cervical cancer?
Whether there is;
- spread into the parametrium
- extension into the vagina
- infiltration of adjacent organs: rectum, ureters, urinary bladder
- metastases to regional lymph nodes (internal iliac and obturator)
In cervical cancer __ (especially __ _______ sequences) is far better than __ at depicting local disease, but __ is often used to determine whether or not there are ______ _______.
In cervical cancer MR (especially T2 weighted sequences) is far better than CT at depicting local disease, but CT is often used to determine whether or not there are distant metastases.
What is the best method of determining wether the endometrium is abnormally thickened?
Transvaginal ultrasound
What is used to assess the degree of myometrial invasion in endometrial cancer?
MR scanning
