Imaging in Obs & Gynae

Question 1

what imaging methods are often used?

Answer 1

ULTRASOUND

CT

MRI

x-ray screening fluroscopy eg hysterosalpingograms (HSG)

functional imaging - PET-CT

Question 2

what are the different indications for using radiology?

Answer 2

diagnosis of pelvic pain assessment of pelvis masses

investigation of abnormal menstrual bleeding

assessment of patients with post-menopausal bleeding

investigation of infertility

interventional radiology - fallopian tube recanalisation, uterine artery embolism etc

Question 3

what is the most common investigation in gynaecology imaging?

Answer 3

US

Question 4

what are the two main US techniques that are used?

Answer 4

transabdominal = scanning using a standard general abdominal US transducer

transvaginal = using a dedicated endocavity high-frequency transducer

Question 5

why must patient have a full bladder for a transabdominal US?

Answer 5

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 the image quality)

Question 6

what are the advantages of transabdominal US?

Answer 6

safe

readily available

no ionising radiation and therefore ideal for children and women of reproductive age

Question 7

what are the disadvantages of a transabdominal US?

Answer 7

difficult to obtain good images in obese patients and in those where there is gaseous distension of bowel

operator dependent

it is difficult to produce exactly the same images every time - therefore not often used to assessing response to cancer treatment

Question 8

identify the bladder, endometrium and vagina on transabdominal US?

Answer 8

Question 9

identify the left ovary on transabdominal US?

Answer 9

Question 10

during a transvaginal US, is the patient required to have a full or empty bladder?

Answer 10

empty = a full bladder can make examination uncomfortable

Question 11

what is the advantage of transvaginal US?

Answer 11

excellent depiction of the pelvic organs

Question 12

what are the disadvantages of transvaginal US?

Answer 12

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)

Question 13

identify the features of a normal transvaginal US?

Answer 13

Question 14

identify a ruptured ovarian cyst on TVUS?

Answer 14

Question 15

what is often used as 2nd line investigation after US in patients presenting with acute abdominal pain?

Answer 15

CT (computed tomography)

Question 16

what types of things within obs and gynae is CT typically used for?

Answer 16

assess post-surgical complications eg 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

Question 17

what are the advantages of CT scanning?

Answer 17

quick

the entire chest abdomen and pelvis can be assessed on one scan

modern multiple detector row scanners produce very thin slices and images can be manipulated to produce coronal and sagittal reformats, as well as the axial source images

Question 18

what are the disadvantages of CT scanning?

Answer 18

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)

Question 19

what is the difference between MRI and CT scanning?

Answer 19

MRI uses radiofrequency energy rather than ionising radiation

Question 20

how is it possible to have MRI scans with different characteristics (eg T1 and T2 weighted scans)?

Answer 20

because it is possible to alter the time between transmitting the RF signal and receiving the RF signal from the patient

Question 21

what are the advantages of MRI scanning?

Answer 21

provides an excellent depiction of pelvic organs

no ionising radiation so can be used in children and women of reproductive age

can give some idea about the composition of soft tissue masses eg do they contain fluid, fat, blood etc

Question 22

what are the disadvantages of MRI scanning?

Answer 22

time consuming

poor deciption of lung parenchyma - a CT scan should be performed if there is query about pulmonary mets

not tolerated if patients have claustrophobia

contra-indicated in patients with pacemakers, many artificial metalic heart valves, nerve stimulators, cochlear implants etc

Question 23

what is MRI scans often used for in gynaecological patients?

Answer 23

cancer staging - esp cervical cancer

further evaluation and characterisation of adnexal and uterine masses, where pelvic US or other imaging have not provided a diagnosis

evaluation of patients with sub-fertility - are there contributory anatomical variations?

MR of the pituitary gland is perfromed in patients with suspected prolactinoma

Question 24

identify a normal MRI of female pelvis in sagittal, axial and coronal view?

Answer 24

Question 25

what abnormal finding is found on this MRI scan?

Answer 25

uterine fibroid

Question 26

what abnormality is found on these MRI scans?

Answer 26

hydrosalpinx

Question 27

endometriosis can be difficult to diagnose and patients may need diagnostic laparoscopy, but what image method may be able to diagnose it?

Answer 27

MRI \*endometriosis deposits contain altered blood and haemoglobin degradation products - these degradation products cause characteristic MR signal changes \*altered blood returns high-signal on T1 sequences (looks white) whereas it returns lower signal sequences on T2 (looks grey)

Question 28

what are dermoid cysts?

Answer 28

ovarian teratomas - contain tissue derived from ectoderm, mesoderm and endoderm and can therefore contain an admixture of many types of tissue but most contain large amounts of fat \*can be difficult to perceive on US but can be seen on MRI and CT

Question 29

what is a hysterosalpinogography (HSG) and what is it used for?

Answer 29

x ray screening procedure - real time imaging (done in 3-5 mins) for assessment of tubal patency in patients with infertility can also assess outline of uterine cavity - cervix is cannulated and radiopaque contrast is instilled to fill the uterine cavity

Question 30

in HSG, what is obtained just before instillation of contrast?

Answer 30

a scout "control" film

Question 31

what are the characteristics of ovarian cancer complications?

Answer 31

disseminates by peritoneal spread - ascites, omental and peritoneal nodules are common sub-diaphragmatic deposits and deposits on the surface of the liver are also seen malignant pleural effusions can result from spread of disease via pleuro-peritoneal communications

Question 32

for ovarian cancers, lymph nodes mets, lung mets and hepatic mets are less common and tend to be seen in patients whom disease behaviour has been modulated by chemothrapy or in cancers with what mutation?

Answer 32

BRCA1

Question 33

what imaging methods are used for initial diagnosis and radiological staging of ovarian cancer?

Answer 33

initial = US staging = CT

Question 34

in cervical cancer, when is MRI better for imaging than CT and vice versa?

Answer 34

MRI (especially T2 weighted) is far better than CT at depiciting local disease CT often used to determine whether or not there are distant metastases eg lung, para-aortic and mediastinal lymphadenopathy

Question 35

what is the best method of establishing abnormally thickened endometrium in patient with PMB?

Answer 35

TVUS

Question 36

in endometrial cancer, when is MRI used and when is CT used? what is the probem with MR scanning in these patients?

Answer 36

MRI - assess degree of myometrial invasion CT - used to loook for distant nodal metastases and pulmonary metastases \*many patients with endometrial carcinoma are obese and they may be too large for MR scanners