Cardiovascular Journal of Africa: Vol 26 No 4 (July/August 2015)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 4, July/August 2015

AFRICA

171

Efficacy of full-fat milk and diluted lemon juice in reducing

infra-cardiac activity of

99m

Tc sestamibi during myocardial

perfusion imaging

Khushica Purbhoo, Mboyo Di Tamba Willy Vangu

Abstract

Background:

When using

99m

Tc sestamibi for myocardial perfu-

sion imaging, increased splanchnic activity creates a problem

in the visual and quantitative interpretation of the inferior and

infero-septal walls of the left ventricle. We sought to determine

whether the administration of diluted lemon juice or full-fat

milk would be effective in reducing interfering infra-cardiac

activity and therefore result in an improvement in image qual-

ity. We compared the administration of full-fat milk and dilut-

ed lemon juice to a control group that had no intervention.

Methods:

The study was carried out prospectively. All patients

referred to our institution for myocardial perfusion imaging

from November 2009 to May 2012 were invited to be enrolled

in the study. A total of 630 patients were randomised into three

groups. Group 0 (G0), 246 patients, were given diluted lemon

juice, group 1 (G1), 313 patients, were given full-fat milk, and

group 2 (G2), 71 patients, had no intervention (control group).

A routine two-day protocol was used and the patients were

given the same intervention on both days. Raw data of both

the stress and rest images were visually assessed for the pres-

ence of infra-cardiac activity, and quantitative grading of the

relative intensity of myocardial activity to infra-cardiac activ-

ity was determined. The physicians were blinded to the inter-

vention received and the data were reviewed simultaneously.

Results:

The overall incidence of interfering infra-cardiac

activity at stress was 84.1, 84.5 and 96.6% in G0, G1 and

G2, respectively (

0.005). At rest it was 91.7, 90.1 and

100% in G0, G1 and G2, respectively (

0.0063). The visual

and quantitative results favoured both milk and lemon juice

in reducing the amount of interfering infra-cardiac activity

versus no intervention.

Conclusion:

The administration of milk or lemon juice result-

ed in a significant decrease in the intensity of infra-cardiac

activity compared to the control group. This reduction in

intensity was even more significant in the milk group for

patients assessed during rest myocardial perfusion imaging.

Keywords:

myocardial perfusion imaging, full-fat milk, lemon

juice, infra-cardiac activity, sestamibi,

99m

Submitted 26/3/13, accepted 25/3/15

Cardiovasc J Afr

2015;

: 171–176

www.cvja.co.za

DOI: 10.5830/CVJA-2015-033

Coronary artery disease is one of the leading causes of death

throughout the world. In most African countries, cardiovascular

disease (CVD) is now the second commonest cause of death

after infectious disease, accounting for 10% of total deaths, and

it is estimated that this burden will double from 1990 to 2020.

1,2

also presents an enormous burden due to morbidity and health

care expenses.

Myocardial perfusion imaging (MPI) is a valuable tool

in the management of patients with CVD and is currently

used in Africa.

The use of single-photon emission computed

tomography (SPECT) myocardial perfusion imaging, with

technetium 99m-labelled radiopharmaceuticals [

99m

Tc sestamibi

(methoxy isobutyl isonitrile) and

99m

Tc tetrofosmin] in conjunction

with either exercise or pharmacological stress is an established

tool for both the diagnosis and prognostication of patients with

ischaemic heart disease.

The basis of the non-invasive approach is that physiological

changes in regional myocardial blood flow or systolic contraction

of the myocardium caused by stress may be more predictive

of outcome than a knowledge of coronary anatomy alone.

Patients with normal perfusion on

99m

Tc SPECT MPI had an

excellent prognosis, whereas patients with abnormal scans had

an increased rate of cardiac death and non-fatal infarction

during follow up.

For perfusion imaging with SPECT, thallium 201 (

201

Tl)

and

99m

Tc-labelled radiopharmaceuticals are commonly used.

The major metabolic pathway for clearance of sestamibi is

the hepatobiliary system, therefore infra-cardiac activity from

the liver and bowel may impact on the interpretation of

the inferior wall after reconstruction. The presence of infra-

cardiac activity leads to artifacts, reducing the desired target-

to-background ratio, which creates difficulty in both visual and

quantitative interpretation of myocardial perfusion.

Activity

may also be present in the stomach due to reflux of tracer into

the gastric lumen from the duodenum, or because of uptake

of free pertechnetate by the gastric mucosa. Infra-cardiac

activity is less common with exercise and is more common with

pharmacological stress and/or in rest studies.

Several different protocols, including a fatty meal, drinking

milk, milk and water, lemon juice, milkshake, carbonated drinks,

iodinated oral contrast, intravenous injection of cholecystokinin,

and the administration of metoclopramide or erythromycin

have been described as a means to reduce the artifacts arising

from abdominal activity.

7-16

Depending on the protocol used,

the mechanisms for these interventions include one or more of

Department of Nuclear Medicine and Molecular Imaging,

Chris Hani Baragwanath Academic Hospital and Charlotte

Maxeke Johannesburg Academic Hospital, University of

the Witwatersrand, Johannesburg, South Africa

Khushica Purbhoo, MB ChB, FCNP (SA), MMed (Nucl Med),

khushica.purbhoo@wits.ac.za

Mboyo Di Tamba Willy Vangu, MD, MMed (Nucl Med), MSc, PhD