def test_diffusion(self):
model = sycomore.como.Model(
sycomore.Species(0 * Hz, 0 * Hz, 1 * um * um / ms),
sycomore.Magnetization(0, 0, 1),
[["foo", sycomore.TimeInterval(500 * ms, 0.1 * rad / um)]])
model.apply_pulse(sycomore.Pulse(40 * deg, 0 * deg))
model.apply_time_interval("foo")
grid = model.magnetization()
for index, _ in sycomore.GridScanner(grid.origin(), grid.shape()):
if index == sycomore.Index(-1):
self.assertEqual(grid[index].p, 0)
self.assertEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0 + 0.003062528150606j)
elif index == sycomore.Index(0):
self.assertEqual(grid[index].p, 0)
self.assertAlmostEqual(grid[index].z, 0.766044443118978)
self.assertEqual(grid[index].m, 0)
elif index == sycomore.Index(1):
self.assertAlmostEqual(grid[index].p, 0 - 0.003062528150606j)
self.assertEqual(grid[index].z, 0)
self.assertEqual(grid[index].m, 0)
else:
self.assertEqual(grid[index].p, 0)
self.assertAlmostEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0)
def setUp(self):
self.species = sycomore.Species(1000*ms, 100*ms, 0.89*um*um/ms)
self.m0 = sycomore.Magnetization(0, 0, 1)
self.flip_angle = 40*deg
self.pulse_duration = 1*ms
self.pulse_support_size = 101
self.zero_crossings = 2
self.TR = 500*ms
self.slice_thickness = 1*mm
self.TR_count = 10
def test_off_resonance(self):
species = sycomore.Species(0 * Hz, 0 * Hz, 0 * um * um / ms)
m0 = sycomore.Magnetization(0, 0, 1)
pulse = sycomore.Pulse(90 * deg, math.pi * rad)
pulse_duration = 1 * ms
pulse_support_size = 101
zero_crossings = 2
# NOTE: in the absence of relaxation and diffusion, the TR is meaningless
TR = 500 * ms
slice_thickness = 1 * mm
t0 = pulse_duration / (2 * zero_crossings)
sinc_pulse = sycomore.HardPulseApproximation(
pulse, sycomore.linspace(pulse_duration, pulse_support_size),
sycomore.sinc_envelope(t0), 1 / t0, slice_thickness, "rf")
refocalization = sycomore.TimeInterval(
(TR - pulse_duration) / 2., -sinc_pulse.get_gradient_moment() / 2)
model = sycomore.como.Model(
species, m0, [["rf", sinc_pulse.get_time_interval()],
["refocalization", refocalization]])
model.apply_pulse(sinc_pulse)
model.apply_time_interval("refocalization")
frequencies = sycomore.linspace(60. * rad / ms, 201)
magnetization = [
model.isochromat(set(), sycomore.Point(), f) for f in frequencies
]
root = os.environ["SYCOMORE_TEST_DATA"]
with open(os.path.join(root, "baseline", "off_resonance.dat"),
"rb") as fd:
contents = fd.read()
baseline = struct.unpack((int(len(contents) / 8)) * "d", contents)
self.assertEqual(len(baseline), 2 * len(magnetization))
for i in range(len(magnetization)):
self.assertAlmostEqual(sycomore.transversal(magnetization[i]),
baseline[2 * i])
self.assertAlmostEqual(magnetization[i][2], baseline[2 * i + 1])
def test_pulse(self):
model = sycomore.como.Model(
sycomore.Species(1 * s, 0.1 * s), sycomore.Magnetization(0, 0, 1),
[["dummy", sycomore.TimeInterval(0 * s)]])
model.apply_pulse(sycomore.Pulse(41 * deg, 27 * deg))
grid = model.magnetization()
for index, _ in sycomore.GridScanner(grid.origin(), grid.shape()):
if index == sycomore.Index(0):
self.assertAlmostEqual(grid[index].p,
0.210607912662250 - 0.413341301933443j)
self.assertAlmostEqual(grid[index].z, 0.754709580222772)
self.assertAlmostEqual(grid[index].m,
0.210607912662250 + 0.413341301933443j)
else:
self.assertEqual(grid[index].p, 0)
self.assertAlmostEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0)
def test_time_interval(self):
model = sycomore.como.Model(
sycomore.Species(math.log(2) * Hz,
math.log(2) * Hz),
sycomore.Magnetization(0, 0, 1),
[["foo", sycomore.TimeInterval(1 * s)],
["bar", sycomore.TimeInterval(1 * s)]])
model.apply_pulse(sycomore.Pulse(45 * deg, 90 * deg))
model.apply_time_interval("foo")
grid = model.magnetization()
for index, _ in sycomore.GridScanner(grid.origin(), grid.shape()):
if index == sycomore.Index(-1, 0):
self.assertEqual(grid[index].p, 0)
self.assertEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0.25)
elif index == sycomore.Index(0, 0):
self.assertEqual(grid[index].p, 0)
self.assertEqual(grid[index].z, 0.5 * (1 + math.sqrt(2) / 2))
self.assertEqual(grid[index].m, 0)
elif index == sycomore.Index(1, 0):
self.assertAlmostEqual(grid[index].p, 0.25)
self.assertEqual(grid[index].z, 0)
self.assertEqual(grid[index].m, 0)
else:
self.assertEqual(grid[index].p, 0)
self.assertAlmostEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0)
model.apply_time_interval("bar")
grid = model.magnetization()
for index, _ in sycomore.GridScanner(grid.origin(), grid.shape()):
if index == sycomore.Index(-1, -1):
self.assertEqual(grid[index].p, 0)
self.assertEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0.125)
elif index == sycomore.Index(0, 0):
self.assertEqual(grid[index].p, 0)
self.assertEqual(grid[index].z,
0.5 + 0.25 * (1 + math.sqrt(2) / 2))
self.assertEqual(grid[index].m, 0)
elif index == sycomore.Index(1, 1):
self.assertAlmostEqual(grid[index].p, 0.125)
self.assertEqual(grid[index].z, 0)
self.assertEqual(grid[index].m, 0)
else:
self.assertEqual(grid[index].p, 0)
self.assertAlmostEqual(grid[index].z, 0)
self.assertAlmostEqual(grid[index].m, 0)
isochromat = model.isochromat()
self.assertAlmostEqual(isochromat[0], 0.125 * math.sqrt(2))
self.assertAlmostEqual(isochromat[1], 0)
self.assertAlmostEqual(isochromat[2],
0.5 + 0.25 * (1 + math.sqrt(2) / 2))
isochromat = model.isochromat(
{sycomore.Index(0, 0),
sycomore.Index(-1, -1)})
self.assertAlmostEqual(isochromat[0], 0.125 * math.sqrt(2) / 2)
self.assertAlmostEqual(isochromat[1], 0)
self.assertAlmostEqual(isochromat[2],
0.5 + 0.25 * (1 + math.sqrt(2) / 2))
def test_pulse_profile(self):
species = sycomore.Species(0*Hz, 0*Hz, 0*um*um/ms)
m0 = sycomore.Magnetization(0, 0, 1)
pulse = sycomore.Pulse(90*deg, math.pi*rad)
pulse_duration = 1*ms
pulse_support_size = 101
zero_crossings = 2
# NOTE: in the absence of relaxation and diffusion, the TR is meaningless
TR = 500*ms;
slice_thickness = 1*mm;
sampling_support_size = 501
t0 = pulse_duration/(2*zero_crossings)
sinc_pulse = sycomore.HardPulseApproximation(
pulse,
sycomore.linspace(pulse_duration, pulse_support_size),
sycomore.sinc_envelope(t0), 1/t0, slice_thickness, "rf")
refocalization = sycomore.TimeInterval(
(TR-pulse_duration)/2., -sinc_pulse.get_gradient_moment()/2)
sampling_locations = sycomore.linspace(
sycomore.Point(0*m, 0*m, 2*slice_thickness), sampling_support_size)
model = sycomore.como.Model(
species, m0, [
["rf", sinc_pulse.get_time_interval()],
["refocalization", refocalization]])
model.apply_pulse(sinc_pulse)
before_refocalization = [
model.isochromat(set(), p) for p in sampling_locations]
model.apply_time_interval("refocalization")
after_refocalization = [
model.isochromat(set(), p) for p in sampling_locations]
root = os.environ["SYCOMORE_TEST_DATA"]
with open(os.path.join(root, "baseline", "pulse_profile.dat"), "rb") as fd:
contents = fd.read()
baseline = struct.unpack((int(len(contents)/8))*"d", contents)
self.assertEqual(len(baseline), 2*3*len(sampling_locations))
for i in range(len(sampling_locations)):
m_test = before_refocalization[i]
m_baseline = baseline[3*i:3*(i+1)]
self.assertAlmostEqual(m_test[0], m_baseline[0])
self.assertAlmostEqual(m_test[1], m_baseline[1])
self.assertAlmostEqual(m_test[2], m_baseline[2])
for i in range(len(sampling_locations)):
m_test = after_refocalization[i]
m_baseline = baseline[
3*(i+len(sampling_locations)):3*(i+len(sampling_locations)+1)]
self.assertAlmostEqual(m_test[0], m_baseline[0])
self.assertAlmostEqual(m_test[1], m_baseline[1])
self.assertAlmostEqual(m_test[2], m_baseline[2])