Nuclear Medicine Resources Manual

Подождите немного. Документ загружается.

CHAPTER 5. GUIDELINES FOR GENERAL IMAGING

340

—Images acquired at 7 days should have at least half the number of

counts of the early images.

(2) SPECT imaging:

—360° rotation.

—64 ¥ 64 matrix.

—A minimum of 60–64 projections for single head gamma cameras

and 120–125 projections for dual head cameras.

—Step and shoot for 40 s per projection.

—Total counts: 3–8 million.

Data are filtered by back-projection using a Metz or Butterworth filter or

other appropriate filters according to the manufacturers’ recommenda

tions. The cut-off frequency or power of the filters should be adjusted

according to the total counts acquired. Alternatively, an iterative recon

struction method should be used if one is available. An attenuation

correction should be considered for deep structures (especially the

abdomen).

(d) Image display:

Data should be displayed in coronal, transaxial and sagittal projections,

1–2 pixels thick, with an additional 3-D volume display. A surface 3-D

display is not adequate.

(e) Mechanism of uptake:

Gallium-67 binds to plasma proteins, especially transferrin, lactoferrin

and ferritin at the iron binding sites, competing with iron. The labelled

plasma proteins cross the target cellular membrane to intracytoplasmic

liposomes or stick to the binding sites on the cellular membrane. There is

no clearance of

Ga from the cells after intracellular localization.

Malignant tumours that are rich in these receptors are gallium-avid.

Conditions that saturate iron binding sites in the plasma interfere with the

biodistribution of

Ga, which remains in the blood pool and has more

bone uptake, thus decreasing its sensitivity.

(f) Radiation dose:

The critical organ is the distal colon, which receives 0.43 mGy/MBq

(0.9

rad/mCi).

5.9.1.6. Interpretation

(a) Patterns of gallium uptake

Normally, one third of the dose will be in the liver, one third in the bone

marrow and spleen, and one third excreted in the urine and by the bowels.

5.9. SPECIAL PROCEDURES IN ONCOLOGY

341

Other sites of normal uptake are the salivary glands, lacrimal glands, nasal

mucosa, external genitalia and growth plates in paediatrics, children and

adolescents. Renal and bladder activity can be seen up to 48 hours post-

injection. Bilateral breast uptake occurs pre-menstrually, during pregnancy and

lactation. Hyperplastic breasts, secondary to oral contraceptives, also can have

bilateral increased uptake. This finding can also be expected in men following

prolonged use of digitalis.

(b) Healing wounds and fractures

The healing time of tissue from the day of an accidental, provoked or

surgical wound until complete healing may vary from two weeks to several

months, depending on the size of the wound and whether the healing is primary

or secondary. In fractures, healing will take several months before completion.

Abnormal patterns secondary to previous chemotherapy and radio-

therapy treatment include the following:

—Bilateral parotid, submaxillary and lacrimal uptake secondary to chemo-

therapy induced sialedenitis.

—Diffuse bilateral lung uptake due to interstitial pneumonia.

—Gastric uptake due to gastritis.

—Renal uptake, especially with cytoxam therapy.

—Urinary bladder uptake secondary to cystitis induced by chemotherapy.

—Thymic uptake due to thymic hyperplasia and rebound phenomenon

requires full clinical data for correct identification, to avoid a biopsy or

further chemotherapy. This is a transient phenomenon seen in about 5–

10% of patients that disappears after a few weeks.

(d) Special patterns of gallium uptake

Special patterns of gallium uptake with no clinical significance following

treatment include the following:

—Mild low-grade bilateral pulmonary uptake.

—Bilateral low-grade hilar uptake.

CHAPTER 5. GUIDELINES FOR GENERAL IMAGING

342

BIBLIOGRAPHY TO SECTION 5.9.1

BARTOLD, S.P., et al., Procedure guideline for gallium scintigraphy in the evaluation of

malignant disease, J. Nucl. Med. 38 (1997) 990–994.

BEN-HAIM, S., et al., Utility of gallium-67 scintigraphy in low-grade non-Hodgkin’s

lymphoma, J. Clin. Oncol. 14 (1996) 1936–1942.

FRONT, D., ISRAEL, O., Present state and future role of gallium-67 scintigraphy in

lymphoma, J. Nucl. Med. 37 (1996) 530–532.

FRONT, D., et al., The continuing clinical role of gallium-67 scintigraphy in the age of receptor

imaging, Semin. Nucl. Med. 27 (1997) 68–74.

JANICEK, M., et al., Early restaging gallium scans predict outcome in poor-prognosis patients

with aggressive non-Hodgkin’s lymphoma treated with high-dose CHOP chemotherapy, J.

Clin. Oncol. 15 (1997) 1631–1637.

SALLOUM, E., et al., Gallium scans in the management of patients with Hodgkin’s disease: A

study of 101 patients, J. Clin. Oncol. 15 (1997) 518–527.

SEABOLD, J.E., et al., Procedure guideline for gallium scintigraphy in inflammation, J. Nucl.

Med. 38 (1997) 994–997.

VOSE, J.M., et al., Single photon emission computed tomography gallium imaging versus

computed tomography: Predictive value in patients undergoing high-dose chemotherapy and

autologous stem-cell transplantation for non-Hodgkin’s lymphoma, J. Clin. Oncol. 14 (1996)

2473–2479.

5.9.2. Scintimammography and sentinel node localization

Mammography is the current accepted approach for screening women

above the age of 40–50 years for the purpose of early detection of breast

cancer. It has been successful for diagnosing more than 80% of cases of breast

cancer at an early stage. As a consequence, patients are being treated at an

earlier phase of their disease and their prognosis has improved. Mammo

graphy, more than any other procedure, has contributed to the more successful

care of breast cancer and survival rates. Nevertheless, it poses a few problems.

Because of the non-specificity of the findings that differentiate between

benign and malignant lesions, many patients are biopsied for benign lesions.

The yield of malignant lesions varies between 15–30% according to the

population screened and the expertise of the interpreting physician.

Mammography is not sensitive in dense breasts, or in breasts that have

been deformed as a result of a previous biopsy, treatment of previous

malignancy by lumpectomy, radiotherapy either of the whole breast or locally

5.9. SPECIAL PROCEDURES IN ONCOLOGY

343

in the form of brachytherapy, previous drainage of a breast abscess, or

following reconstruction surgery of the breast and mammoplasty. Similar

problems are also encountered in patients with fibrocystic disease of the breast.

There have been various attempts to reduce the number of biopsies for

benign lesions in order to save costs and to avoid the psychological impact on

those patients who are left with a scar following lumpectomy. These attempts

involved the use of

99m

Tc-sestamibi,

201

Tl-chloride and

F-FDG but none gave

convincing results that could substitute for biopsy. All such attempts failed to

demonstrate major clinical value because the sensitivity of mammography for

small lesions under 2 cm is less than 70%. Therefore, it is very difficult to

substitute for a biopsy whenever there is suspicion of malignancy in the

mammogram.

Once the diagnosis of malignancy has been established, the next step is

determining the stage of the disease in order to decide on the best treatment

for the patient. Eighty per cent of breast cancers are discovered at an early

state and are operable. The most important staging criterion in these patients is

the status of axillary node involvement by malignant cells. Until recently, total

axillary node dissection with histological examination was the only way for

axillary staging. Axillary dissection requires longer hospitalization and is

followed by complications in more than 30% of patients due to infection, pain,

oedema of the arm and limitation of movements. This is a high price to pay,

since in the majority of patients the pathological examination of the axillary

specimen shows no evidence of metastatic spread. In stage T-1 lesions (<2 cm),

axillary node involvement varies from 3 to 19%.

The new approach to localize the sentinel node, either by methylene blue

or by radionuclide techniques, represents a major development. It is considered

the second most important milestone for the treatment of breast cancer

following the changes from the mutilating radical or modified radical

mastectomy to the more conservative approach of lumpectomy and post-

operative radiotherapy. Sentinel node localization is successful and accurate in

more than 98% of patients. Those who show no involvement of the sentinel

node after microscopic examination of the frozen sections, haematoxylin and

eosin staining and special PCR staining do not require further dissection of the

axillary nodes. Patients who have metastatic disease to the sentinel nodes

require dissection of all the axillary nodes. The significance of a few metastatic

microscopic cells detected only by PCR staining is not yet known. Protocols are

currently under evaluation in order to determine the prognostic impact of these

findings. The sentinel node approach has a negative predictive value of more

than 99% in T-1 lesions, which constitutes the most significant feature of this

approach.

CHAPTER 5. GUIDELINES FOR GENERAL IMAGING

344

5.9.3. Procedure recommendations for scintimammography

5.9.3.1. Patient selection

Nothing else is as effective as a biopsy whenever a malignant lesion is

suspected. A biopsy, however, is only appropriate for those patients for whom

the results of a mammography are inconclusive, namely under the following

conditions:

—Dense breasts, when there is clinical suspicion of a mass that cannot be

detected in the mammogram. Palpable masses in dense breasts should be

always biopsied irrespective of size. Scintimammography might help

localize the site of a biopsy.

—A breast with distortion of its architecture by previous surgery,

irradiation or reconstructive procedures.

—Fibrocystic disease of the breast, when there is a suspicious mass on the

mammogram. Scintimammography helps guide the surgeon to pinpoint

the biopsy.

5.9.3.2. Patient preparation

The procedure, its benefits and the time needed to perform it should be

explained to the patient when obtaining her consent.

5.9.3.3. Radiopharmaceuticals

Technetium-99m sestamibi is preferred to

201

Tl-chloride because of the

higher injected dose and greater photon flux, as well as data from tissue culture

experimental work that show a higher uptake of

99m

Tc-sestamibi than

201

Tl-

chloride in breast cancer cells. Other

99m

Tc compounds such as tetrofosmin can

also be used.

(a) Dose and route of administration:

—Technetium-99m sestamibi or other

99m

Tc labelled compounds: 555–

740

MBq (15–20 mCi).

—Thallium-201 chloride: 111–148 MBq (3.0–4.0 mCi).

(b) Route of injection:

—An intravenous injection should not be given in the arm on the side of

the suspicious breast mass. Either the other arm or a foot should be

used.

5.9. SPECIAL PROCEDURES IN ONCOLOGY

345

—It is important to inject straight into the vein. Any extravasation will

lead to lymphatic permeation and uptake by the lymph nodes in the

axilla that could be misleading for the interpretation of axillary

metastasis.

—In patients with bilateral breast masses, injection in the dorsal veins of

the foot is recommended.

—Although imaging can be started 15 min after injection, longer periods

of up to two hours are indicated in patients with suspected inflam

matory lesions. It is known that both thallium (

201

Tl) and

99m

Tc-

sestamibi wash out with time in benign lesions. In most malignant

lesions, the washout is usually slower than in benign inflammatory

lesions.

5.9.3.4. Procedure and equipment

The following procedure and items of equipment are recommended:

(a) Patient positioning and views to be acquired:

—The patient should lie face down with the affected breast resting on a

foam lined aperture on the imaging table. The arm on the side to be

imaged should be raised above the head. The patient should be in the

prone position and with the breast hanging, relaxing the pectoralis

muscle and allowing separation of the breast tissue from the chest wall

muscles and from cardiac and liver activity.

—Lateral projections should be acquired for each breast.

—A posterior oblique view of the affected breast is recommended.

—Following the two lateral views, an anterior view of the thorax with the

arms raised above the head is needed for axillary evaluation.

(b) Recommended gamma camera:

—Single or double head.

—Large FOV.

—The collimator should be of low energy and of the parallel hole, high

resolution type.

—Matrix size of 128 ¥ 128 ¥ 16.

—The zoom factor should be sufficient for the breast to cover two thirds

of the FOV of the gamma camera in the lateral and posterior oblique

projections. In the anterior projections, both breasts, the axillae and

supraclavicular regions should be included so magnification is not

critical.

—Acquisition time of 10 min per projection.

CHAPTER 5. GUIDELINES FOR GENERAL IMAGING

346

5.9.3.5. Interpretation

The interpretation should be made in steps, firstly blind to other data and

then with all the information available from the clinical examination,

mammography and any previous interventions.

Malignant tumours show up as areas of focal increased uptake that can be

graded in different ways according to the intensity and distribution of the

uptake. Difficulties usually occur with small lesions. Large lesions are generally

very well evaluated.

Lymph node metastases should be checked in the axillae, supraclavicular,

infraclavicular and internal mammary regions.

Although no special processing is needed, reporting directly from the

computer screen with threshold enhancement and background subtraction is

recommended.

5.9.3.6. Reporting

Details should be provided on the radiopharmaceutical used, the site of

injection, waiting period, projections acquired and the intensity of uptake, as

well as the confidence in the interpretation.

5.9.4. Procedure recommended for lymphoscintigraphy for axillary sentinel

node localization in breast carcinoma

5.9.4.1. Patient preparation

No special preparation is required for patients undergoing surgery the

same day. At least three hours should be allowed for the usual pre-surgical

preparation. Patients whose surgery is scheduled for the next morning can be

injected and imaged late in the afternoon. The patient should be made aware of

the procedure and provide her consent for the study.

5.9.4.2. Patient selection

Preference is given to:

—Patients with primary breast lesions that have been proven malignant by

a needle or core biopsy;

—Patients where the lesion is up to 3 cm in size;

—Patients who have not undergone a previous lumpectomy.

5.9. SPECIAL PROCEDURES IN ONCOLOGY

347

5.9.4.3. Patient exclusion

Usually excluded from the procedure are:

—Patients with a breast lesion over 4 cm in diameter;

—Patients showing signs of advanced stage of the disease such as retracted

nipples, oedema and orange skin, bleeding from the nipple, or palpable

lymph nodes in the axilla or supraclavicular region;

—Patients with local recurrence;

—Patients with multicentre malignant lesions;

—Patients where the margins are ill defined at the time of surgery or if

recognized clinically.

5.9.4.4. Radiopharmaceuticals and procedure

Technetium-99m labelled radiopharmaceuticals with reproducible

200

nm particle size are used such as:

—Technetium-99m antimony SC;

—Unfiltered

99m

Tc-SC;

—Filtered (0.22 mm)

99m

Tc-SC.

Technetium-99m HSA and

99m

Tc-dextran have been mentioned. They

travel faster through the lymphatic system and allow visualization of

proximal lymph nodes in addition to the sentinel node, although this can be

disadvantageous.

5.9.4.5. Site of injection

(a) Intratumoral injection

Intratumoral injection should only be used in conjunction with

ultrasound guidance because of difficulty in precisely locating the mass in

certain patients. Lack of lymphatic system in the tumour may produce late or

no migration of particles.

(b) Injection around the tumour

A 24 gauge needle, 2 in (51.2 mm) long should be inserted at four points

around the tumour, with the injection site less than one centimetre from the

edge of the tumour at four quadrants, 90

apart. This presents difficulties in

CHAPTER 5. GUIDELINES FOR GENERAL IMAGING

348

dense large breasts. After lumpectomy, injection around the tumour leads to

reduced visualization of the sentinel node in a large percentage of patients as a

result of distortion of the lymphatic vessels. It is imperative to avoid injecting

into the wall or into the cavity of the post-surgical lumpectomy site.

The lymphatic system of the breasts converge from all sectors towards the

areola and then intradermally towards the draining lymph node. Subcutaneous

injection is slower than intradermal injection. In order to achieve the desired

results, an intradermal injection of 0.3–0.4 mL should be given using a TB

needle. By inducing a bleb in the skin to increase intracapillary pressure, the

injected particles will be forced into the lymphatics. After the injection, the site

should be massaged by applying pressure with a finger for 10

s. Using this

technique, the sentinel node can be visualized in less than 5 min in most

patients.

Intradermal injection is preferred in patients who have previously had a

lumpectomy. The radiopharmaceutical should be injected in these patients on

both sides of the centre of the scar, in the section of the breast overlying the

breast mass. In non-palpable masses, localization by ultrasonography is

recommended and the ultrasonographer should mark the location of the breast

mass. Internal mammary lymph nodes, however, have less chance of being

visualized with intradermal injection.

5.9.4.6. Dose and volume injected

The following procedure should be applied:

(a) Injection around the tumour:

—Patients imaged on the day of surgery require 18.5 MBq (0.5 mCi) in

mL saline. Inject 1.0 mL at four quadrants, 90

apart.

—Patients undergoing surgery the following day have an increased total

dose of 37 MBq (1.0 mCi) in 4 mL saline. Warming the saline to body

temperature helps reduce the pain at the injection site that is frequently

experienced by patients.

(b) Intradermal injection:

—Patients imaged on the day of surgery require 8–12 MBq (0.2–0.3 mCi)

in 0.3–0.4 mL saline.

—Patients undergoing surgery the following day have an increased dose

of 37 MBq (1.0 mCi) in 0.3–0.4 mL saline.

5.9. SPECIAL PROCEDURES IN ONCOLOGY

349

5.9.4.7. Mode of acquisition

Dynamic images of 30–60 s each should be acquired in a 128 ¥ 128 matrix

in a lateral projection to include the breast and the axilla, starting immediately

after the injection, for a total of 30–45 min. This is followed by static acquisition

for 5 min in the lateral and anterior projections. If the nodes are still not seen,

static images should be repeated after two hours. A transmission scan is

recommended using either

99m

Tc or

Co flood sources to outline the body

contours.

5.9.4.8. Display of data

Attention should be paid to the following points:

—Dynamic images are summed and displayed representing 1 or 2 min each.

—Static images with transmission are used to provide anatomical

references.

—The upper threshold should be adjusted for optimal visualization as well

as masking of the injection site.

5.9.4.9. Reporting

The report should include:

—Clinical history;

—Radiopharmaceutical used, dose, volume and route of injection;

—Whether the study succeeded in ‘localizing’ the sentinel node;

—Whether the sentinel node localized is in the lower or middle axilla

(upper axilla is rare);

—Whether internal mammary and/or other (intrapectoral or supracla-

vicular) lymph nodes are visualized alone, or in association with axillary

nodes.

5.9.4.10. Intra-operative procedures

The intra-operative procedures are summarized below:

(a) The surgeon injects Methylene Blue (Blue Patent V) around the breast

mass.