Isaac R. Francis, MD #{149}Thomas William Ensminger, MD, PhD

Malignant Spectroscopy Chemical

L. Chenevert, PhD #{149} Barry Suzette Walker-Andrews,

neoplasms

P

of the

section

in

that

was occupied by tumor: less than 50% (group A) or more than 50% (group B). In group B, all phosphomonoester/-adenosine

triphosphate

studies

ratios

Radiology

1991;

shown

MR

spectroscopy

of liver

AND

METHODS

Healthy volunteers and patients whose liver tumors were detected with other inaging techniques and proved by means of biopsy were eligible for our study. To minimize the effects of therapy on the P-31 spectrum, the following study entry criteria were established retrospectively: (a) Patient had recently undergone themotherapy or radiation therapy (within 4 weeks) and had not responded, (b) therapy had failed and patient had progressive liver disease as determined with computed tomography, or (c) patient had stable or mildly progressive disease (usually from metastatic neuroendocrine tu-

Liver neoplasms, diagnosis, Liver neoplasms, MR studies, 761.1214. Magnetic resonance (MR), chemical shift #{149}Magnetic resonance (MR), phosphorus studies #{149} Magnetic resonance (MR), spectroscopy 761.33

on

MATERIALS

terms:

761.32,

resonance has

tumors (15,16). To address this issue, as well as to determine the feasibility and application of MR spectroscopy of the liver in clinical practice, we undertook this study of image-localized P-31 MR spectroscopy of malignant human liver tumors by using the onedimensional chemical shift imaging (CS!) technique (21). The methods, results, and limitations of this study form the basis of the present report.

were significantly higher than normal (P < .001). Hepatocellular carcinomas and metastases from various primary neoplasms could not be differentiated on the basis of spectral characteristics and metabolite ratios. Limitations of one-dimensional surface coil CSI prevented separation of spectra of small tumors and tumors deep within the liver parenchyma from spectra of normal liver parenchyma. Index

spectroscopy

#{149}

180:341-344

mors). I

From

the Departments

of Radiology

(I.R.F., T.LC.)

and Internal

Medicine

and Pharmacology

the DeHenry Ford Hospital, Detroit (B.C.); LaRavoire, France (L.C.); and the DeRadiology and Nudear Medicine, Stanford University, Stanford, Calif (G.M.G.). Received February 23, 1990; revision requested April 17; final revision received and accepted April 8,1991. Supported in part by the Tumor Imaging Core of the University of Michigan (WE., S.W.A.), University partment of Radiology, partment of Diagnostic

Cancer Center, NIH ©RSNA, 1991

of Michigan,

P30 CA 46592-01-Al.

1500

E Medical

Address

Center

reprint

Dr, Ann

requests

Arbor,

to LR.F.

Collomb, MD

MS

1 MR

potential utility in the evaluation of a variety of malignant neoplasms (116), and more recently its role has been extended to indude the momtoring of tumor response to therapy (17-20). Many studies have shown that, compared with normal tissues, malignant tumors of varying histologic descriptions have elevated levels of phosphomonoesters (PMEs) and, hence, elevated PMF43.-adenosine triphosphate (ATP) ratios (1-16). However, there are still relatively few

(30 metastases

analyzed

magnetic

HosiiORUs-31

(MR)

from a variety of primary tumors and seven hepatocellular carcinomas) and seven healthy volunteers. Tumors were grouped according to the percentage

MD #{149}Laurance Gary M. Glazer,

Hepatic Tumors: P-3 with One-dimensional Shift Imaging’

To determine the clinical feasibility and applicability of phosphorus-31 magnetic resonance (MR) spectroscopy and to assess its potential for characterization of human hepatic tissue, one-dimensional chemical shift imaging (CSI) was performed 37 patients with various malignant hepatic

Gubin, RN

#{149}

Thirty-seven patients with malignant liver tumors met one of these criteria and were induded in the study, as were seven healthy volunteers who served as controls. The 37 patients induded 30 with metastases from various primary tumors and seven with primary hepatocellular caranoma. The primary tumors in the 30 patients with liver metastases induded cobrectal cancer (n = 16), gastrointestinal neuroendocrine tumors such as carcinoids and islet cell tumors (n = 8), and a variety of other tumors (n 6). Patients with himors (metastases and hepatocellular cardnomas) ranged in age from 19 to 81 years, with a mean of 54 years. The ages of the volunteers ranged from 24 to 38 years, with a mean of 28 years. The metastases were 1-18 cm in diameter, with a mean of =

7 cm;

the hepatomas

were

1-14

cm in di-

ameter, with a mean of 8.5 cm. Spectroscopy was performed at the time of initial discovery of the tumor in seven of 30 patients with metastases and six of seven patients with hepatocellular cardnoma. No attempt was made to modify the diet of the patients or the volunteers before MR spectroscopy was performed. All studies system

Signa

were performed on a I .5-T (GE Medical Systems, Mil-

waukee). The imaging technique consisted of Ti-weighted axiallocalizing imaging (repetition time [TRI, 500 msec; echo time [TEl,

20 msec)

to define

the location

of the

for surface coil placement. With the patient supine, an 8- or 14-cm surface coil (depending on the size and location of the tumor) was placed on the skin surface, either along the anterior abdominal wall or the right lateral thoracoabdominal wall, over the lesions best suited for obtaining a tumors

P-31

MR spectra.

larger Optimal firmed

ages

and/or

These

were

superficially

usually

located

the

tumors.

coil positioning was then consubsequent TI-weighted inthat displayed a tube of high-signalwith

intensity material around the coil circumference. In the volunteers, the coil was placed on the right lateral thoracoabdominal wall for sampling

of the right

lobe.

MI 48109-0030;

Abbreviations: ATP = adenosine triphosphate, CS! = chemical shift imaging, PME phosphomonoester, S/N = signal-to-noise TE = echo time, TR = repetition time.

=

ratio,

341

Surface

coil-localized

proton

shimming

PME/I-ATP

was performed in approximately one-half of the studies by adjusting the first-order gradients. Shimming could not be performed in all cases because of personnel and time constraints. A P-31 one-dimensional

chemical

lected

along

ing

the

image

was

of signals

averaged,

128 phase-encoding 256

complex

full spectral coding

data

width.

pulse

0.4-msec

steps

(1-cm

points;

and

A 0.5-msec

followed thus

ma-

sec2-kHz

and

delayed

to

for

resolution the price

resolution to apthis phase-encoding is adequate paid in the

when signal-to-

noise ratio (S/N) and phase distortion required for finer resolution over longer phase-encoding periods. The total duralion of the studies ranged from 60 to 90 minutes, with the spectroscopy component of the study requiring 21 minutes 25 seconds of acquisition time and an addi-

5-10 minutes

of setup

time.

The P-31 data were processed ponential filtering (10 Hz), zero

with exfiffing,

two-dimensional Fourier transform to a 128 x 1,024 matrix, and manual phase correction.

The

from

baseline

signal

phase

distortion

digitization

encoding

was

delay reduced

that

results

due to by

means

of

a correction routine that used a third-order polynomial fit of the baseline. All of

these

steps

were

dor-provided the 1280 Data

ments, data

performed

software Station;

Fremont,

NMR

by using

yen-

(GEN ver.9.0 for GE NMR Instru-

Calif) on a spectroscopy

station Nicolet Instruments,

1280 computer Fremont, Calif).

ally only one spectrum

(GE Usu-

per one-dimen-

sional CS! data set was analyzed in detail. This spectrum was selected to match the depth of interest in the lesion as measured on proton images. While spectra were quantified by means of several methods (peak heights vs manual and automated fit of peak areas), problems

with

greatest

peak

overlap

confidence

curve-fitting

caused Only

mated fit of lorentzian curves by using NMRI spectroscopy cuse, puter

to have

the

to the peaks data analysis

(New Methods Research, SyraNY) operating on a VAX 1 1t750 com(DEC,

Maynard,

Mass).

The

PME,

inorganic phosphate, phosphodiester, phosphocreatine contaminant, and ATP peaks were quantified such that sets of ratios could be generated. Usually

342

only

Radiology

#{149}

one

spectrum

per

mensional

=

standard

Mean

SD 0.18 0.70 1.90

7

0.35

12 18 2

0.99

5

1.39

deviation,

1.81 1.15

NA

Ratio

NS

Bonnferoni Correction

Significance NA p P

1.34 0.64

not applicable,

=

one-di-

CS! data

set was analyzed

in

detail. This spectrum was selected by using the known 1-cm section spacing of the one-dimensional CS! data and the depth from the body wall (usually easily defined on one-dimensional CS! data) to the desired region in the lesion as measured on the proton image. Patients were grouped on the basis of the estimated percentage of the selected one-dimensional CS! section that was occupied by tumor. This area was

approximated

by superimposing

template over plate displayed

the proton images. The ternan idealized stack of 1-cm

one-dimensional

NA NS

.05