Imaging in Obs and Gyn Flashcards
What imaging techniques are used in obs and gyn?
Ultrasound
CT
MRI
X-ray screening fluoroscopy – e.g.
hysterosalpingograms (HSG)
Functional imaging – PET-CT
What are indications for using radiology in obs and gyn?
Diagnosis of pelvic pain – looking to check for 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/post-menopausal bleeding clinic)
Investigation of infertility (these patients may also undergo MR scanning of the pituitary)
Interventional radiology – fallopian tube recanalisation, uterine artery embolisation etc
What is the most common investigation type for gynaecological imaging?
Ultrasound scan
Used commonly in gynaecological and also in ante-natal circumstances
What are the pros of using ultrasound scanning in obs and gyn?
Relatively cheap
Safe – no ionising radiation
Provides very good definition of different pelvic organs
Can be used in the clinic as an adjunct to pelvic examination
What are the 2 main ultrasound techniques used in obs and gyn?
Transabdominal - scanning using a standard general abdominal US transducer
Transvaginal - scanning using a dedicated endocavity high- frequency transducer
Both techniques can be used during the same visit
How are pelvic organs scanned in transabdominal ultrasound?
The pelvic organs are scanned through the anterior abdominal wall
A brief assessment can be used before transabdominal US, what can this check for?
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 patient have full bladder during transabdominal US?
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 ultrasound beam and degrades image quality)
Advantages of transabdominal US?
- Safe
- Readily available
- No ionising radiation and therefore ideal for children and women of reproductive age
Disadvantages of transabdominal US?
- It is difficult to obtain good images in obese patients and in patients where there is gaseous distension of the bowel
- Operator dependent (the quality of the ultrasound examination is dependent in large part on the skills of the operator).
- It is difficult to produce exactly the same images every time the patient attends and this means ultrasound is not often used for assessing the response to cancer treatment
Transvaginal ultrasound requires patient to have full bladder. True/false?
False
Transabdominal US requires full bladder.
Transvaginal US prefers an empty bladder as a full bladder can make the examination uncomfortable
Advantages of transvaginal scanning?
Excellent depiction of the pelvic organs
Disadvantages of transvaginal scanning?
More invasive procedure
Not suitable for individuals who have not been sexually active
Can sometimes just demonstrate “the tip of the iceberg” and may not depict the full extent of large pelvic masses (ideally transvaginal scan should follow a transabdominal scan which allows better overview)
CT scanning can often be used as a second-line investigation after ultrasound in patients presenting with acute abdominal pain. True/false?
True
What can CT scanning be used for in obs and gyn?
Can be used to assess post-surgical complications – e.g.small bowel obstruction secondary to adhesions, post-operative collections/abscesses etc.
Staging of gynaecological malignancy, especially ovarian and endometrial cancers
Assessing response to treatment in patients after chemotherapy +/- radiotherapy
Advantages of CT scanning in obs and gyn?
Quick
The entire chest abdomen and pelvis can be assessed on one scan
Modern multiple detector row (“multislice”) scanners produce very thin slices and images can be manipulated to produce coronal and sagittal reformats, as well as the axial source images
Disadvantages of CT scanning in obs and gyn?
High radiation dose (equivalent to about 160 chest x-rays) with a significant dose delivered to the ovaries
Therefore used sparingly in children and patients of reproductive age
Does not provide optimal depiction of different pelvic organs (MR is better at providing good tissue resolution)
MRI scanning uses ionising radiation. True/false?
False
Uses radiofrequency energy rather than ionising radiation
Advantages of MRI scan?
Provides an excellent depiction of pelvic organs
No ionising radiation and is therefore suitable for children and women of reproductive age
Can give some idea about the composition of soft tissue masses – e.g. do they contain fluid, fat, blood etc
Disadvantages of MRI scan?
Time-consuming
Poor depiction of lung parenchyma – a CT scan should be performed if there is query about pulmonary metastases
Not tolerated if patients have claustrophobia
Contra-indicated in patients with: pacemakers, many artificial metallic heart valves, nerve stimulators, cochlear implants etc.
What specific uses of MRI in obs and gyn?
Cancer staging – especially cervical cancer
Further evaluation and characterisation of adnexal and uterine masses, where pelvic ultrasound or other imaging have not provided a diagnosis
Evaluation of patients with sub-fertility
MR of the pituitary gland is performed in patients with suspected prolactinoma
Endometriosis may be difficult to diagnose, what technique could patients require?
Diagnostic laparoscopy
How can endometriosis be diagnosed on MRI scan?
Endometriosis deposits contain altered blood and haemoglobin degradation products.
These degradation products cause characteristic MR signal changes, and, in the appropriate clinical context, endometriosis can be diagnosed on MRI scans.
What are dermoid cysts?
Also known as ovarian teratomas and contains tissue derived from ectoderm, mesoderm and endoderm. They can therefore contain an admixture of many types of tissue, but most contain a large amount of fat.
What is HSG (hysterosalpingography) and its use?
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 does HSG procedure usually take to complete?
Procedure usually completed ~3-5 minutes
What is the classification for cancer staging?
Cancers are staged using the TNM (Tumour Nodes Metastases) classification
Why is establishing the stage of the cancer important in treatment?
Staging plays an important role in treatment planning and can assist in discussions about the patient’s prognosis
A pre-treatment scan serves as a “baseline” study so that subsequent scans can be used to assess response to treatment (chemotherapy, radiotherapy etc)
How does ovarian cancer disseminate?
By peritoneal spread
Imaging used for initial diagnosis of ovarian cancer?
Ultrasound (ovarian masses)
What is the usual method used for radiological staging of ovarian cancer?
CT scan
What cancers are linked to the BRCA 1 gene?
Ovarian and/or breast cancer
When staging cervical cancer, what is important to note?
Important to determine 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)
For endometrial cancer, what is the best method of establishing abnormally thickened endometrium in a post-menopausal patient with PMB?
Transvaginal ultrasound
Uses of MRI and CT in endometrial cancer?
MR scanning can be used to assess the degree of myometrial invasion
CT scanning is used to look for distant nodal metastases and pulmonary metastases
Why can MRI scanning be a problem for patients with endometrial cancer?
Many patients with endometrial carcinoma are obese, and they may be too large for the narrow bore of MR scanners
