[Imaging of the postsurgical liver]. / Imagerie du foie opéré

The appearance of the normal postsurgical liver and of potential complications specific to the type of liver resection performed (partial hepatectomy, cyst fenestration, RF ablation) must be well known by radiologists for early detection and treatment of postoperative complications. Early postoperative imaging of the liver aims at detecting vascular, biliary and extrahepatic complications and relies mainly on Doppler US and CT.

Sonographic preoperative assessment of liver volume before major liver resection.

OBJECTIVE: The use of ultrasonography is widespread for both the diagnosis and treatment of liver tumors. However, the measurement of liver volume by ultrasonography is not commonly done. We report an original method of liver volumetry using ultrasonography and an investigation into the usefulness of ultrasonography in this context. METHODS: The data for 50 patients undergoing various types of major hepatectomy were collected. We preoperatively measured liver volume using ultrasonography, dividing the liver into three main compartments according to precise anatomical landmarks, and then made comparisons with the volume of the actual specimen after hepatectomy, for all of the study participants. RESULTS: Total volume correlation between the two groups was good (r = 0.916, P < 0.001). However, the correlation was weaker in cases of right hepatectomy compared with other types of hepatectomy. CONCLUSION: This study demonstrates the possibility of doing liver volumetry using an ultrasound device. Further investigation to establish the reliability of this easily available and noninvasive approach is needed.

Measuring earthquakes from optical satellite images.

Système pour l'Observation de la Terre images are used to map ground displacements induced by earthquakes. Deformations (offsets) induced by stereoscopic effect and roll, pitch, and yaw of satellite and detector artifacts are estimated and compensated. Images are then resampled in a cartographic projection with a low-bias interpolator. A subpixel correlator in the Fourier domain provides two-dimensional offset maps with independent measurements approximately every 160 m. Biases on offsets are compensated from calibration. High-frequency noise (0.125 m(-1)) is approximately 0.01 pixels. Low-frequency noise (lower than 0.001 m(-1)) exceeds 0.2 pixels and is partially compensated from modeling. Applied to the Landers earthquake, measurements show the fault with an accuracy of a few tens of meters and yields displacement on the fault with an accuracy of better than 20 cm. Comparison with a model derived from geodetic data shows that offsets bring new insights into the faulting process.

[Imaging of symptomatic giant hemangioma]. / Imagerie d'un angiome géant symptomatique.

A case of symptomatic giant hemangioma of the liver with fever, anemia, and increased erythrocyte sedimentation rate is reported. Spontaneous hyperdense areas at CT, and high signal-intensity areas at T1-weighted MR images were demonstrated within the hemangioma. Marked hemorrhagic zones demonstrated at pathologic examination may explain these uncommon clinical and imaging features.

[Non-vascular retroperitoneal emergencies]. / Urgences rétropéritonéales non vasculaires.

Acute renal disease, in the absence of trauma, consist of acute renal obstruction, renal infection or a combination of the two. The diagnosis of acute renal colic is usually performed with ultrasound or excretory urography whereas parenchymal involvement in renal infection is best demonstrated on computed tomography images. The aim of radiologic investigations is to look for complications in order to guide the treatment, particularly percutaneous procedures. Other less common acute renal diseases include renal vein thrombosis optimally analyzed with contrast injection to demonstrate renal function, and spontaneous renal hemorrhage, which implies careful renal assessment looking for a small tumor. Acute psoas compartment diseases include hematomas and abscesses. Computed tomography is the best diagnostic tool and the examination of choice for the follow-up lesions and to guide percutaneous drainage.

[Ultrasonography of the tendons of the rotator cuffs of the shoulder]. / Etude échographique des tendons des muscles rotateurs de l'épaule.

After a short review of the use of ultrasonography to study shoulder rotator tendons, the technique of the investigation is described, as well as the main landmarks, findings indicative of complete rotator cuff tear, and limitations of ultrasonography in this indication. A number of issues concerning the preoperative workup are discussed. Results in a prospective study of 100 patients are reported. Findings upon ultrasonography, arthrography, and surgical exploration in these patients are analyzed comparatively. Sensitivity and specificity of ultrasonography for the diagnosis of complete rotator cuff tear (RCT) were 95% and 100%, respectively. These data show that ultrasonography is a reliable investigation for confirming, detecting, and evaluating RCT, although extensive experience with the technique is required.

Recording conditions of an array-illuminator hologram based on the Talbot effect.

We propose a new process for making an array illuminator that combines the Talbot effect and the principle of holography. For high diffraction efficiency we use a thick phase hologram recorded in dichromated gelatin. Special conditions for the intensity uniformity of the recorded wave are required with this type of hologram. We discuss these conditions as a function of the pixel shape.

[Ultrasonography of the shoulder: diagnosis of rupture of tendons of the rotator muscles]. / Echographie de l'épaule. Diagnostic de rupture des tendons des muscles rotateurs.

After a short historical review of the use of ultrasonography to study shoulder rotator tendons, the technique of the investigation is described, as well as the main landmarks, findings indicative of complete rotator cuff tear, and limitations of ultrasonography in this indication. A number of issues concerning the preoperative workup are discussed. Results in a prospective study of 24 patients are reported. Findings upon ultrasonography, arthrography, and surgical exploration in these patients are analyzed comparatively. Sensitivity and specificity of ultrasonography for the diagnosis of complete rotator cuff tear (RCT) were 95% and 100%, respectively. These data show that ultrasonography is a reliable investigation for confirming, detecting, and evaluating RCT, although extensive experience with the technique is required.

Optical inner-product implementation of neural networks models.

The Hopfield neural network model is described in terms of inner product, i.e., as a matched filtering step followed by a pattern synthesis step. Optical implementation by two cascaded coherent filtering setups with holographic matched filters is described. Suitable encoding of information in the form of bipolar (positive or negative) amplitudes in one hologram and of non-negative amplitudes in the other allows one to deal only with non-negative quantities in the input and output planes, thereby avoiding use of multiple channels and coherent detection. The performance of this scheme is analytically evaluated. The above coding can moreover be adapted to the cases of nonzero average memorized states and to the higher-order models associated to Hopfield's algorithm. Numerical simulations and experimental results are presented to illustrate the analysis.

Optical cellular processor architecture. 2: Illustration and system considerations.

In the first paper of this series, we proposed a definition for the concept of 2-D optical cellular processors. In this second part we present an optical experimental setup capable of implementing a binary pattern recognizer. A 2-D hologram array is used in conjunction with a multiplexed holographic illumination for the interconnection and makes the system easily programmable. Thick phase holograms on dichromated gelatin cause distortion and their field of view is constrained by the Bragg effect. These problems are investigated in relation to all the system aberrations and a set of optimal parameters for one distortion-free configuration is given. Experimental results are shown.

Optical cellular processor architecture. 1: Principles.

General characteristics and advantages of 2-D optical cellular processors are listed and discussed, with reference to the concepts of cellular automata, symbolic substitution, and neural nets. The role of optical interconnections and of quasilinear processing combining linear array operations and pointwise nonlinearities is highlighted. An architecture for optical implementation of cellular automata is introduced; it features high density 3-D optical shift-invariant interconnections and programmability of the interconnection pattern through adequate use of holographic connectors.

[Cystine calculi. In vitro solubility and chemical structure]. / Calculs de cystine. Solubilité in vitro et structure chimique.

A series of cystine stones extracted from the same subject by pyelotomy was used to study the in vitro solubility of these stones in various solutions. Isotonic bicarbonated saline presented a definite dissolving action, but the stone dissolved relatively slowly alpha-mercapto-propionyl-glycine was much more active, even when mixed urine. N-acetylcystine had the same degree of effectiveness as alpha-mercapto-propionyl-glycine. One stone in this series, which was partially covered by a coating of calcium phosphate, dissolved much more slowly than the other stones. In subjects with cystine stones, longstanding large stones are frequently mixtures of phosphates and cystine and, in 21 cases, chemical analyses and infra-red spectrography demonstrated the presence of calcium phosphate on the surface or in the inferior of these stones, associated with ammoniaco-magnesium phosphate in three cases. The presence of phosphates makes oral medical treatment ineffective, but mixed stones are more friable than pure cystine stones and are therefore easier to treat by extracorporeal lithotripsy.

Right- and left-handed helixes of poly[d(A-T)].poly[d(A-T)] investigated by infrared spectroscopy.

The secondary structures of double-stranded poly[d(A-T)].poly[d(A-T)] in films have been studied by IR spectroscopy with three different counterions (Na+, Cs+, and Ni2+) and a wide variety of water content conditions (relative humidity between 100 and 47%). In addition to the A-, B-, C-, and D-form spectra, a new IR spectrum has been obtained in the presence of nickel ions. The IR spectra of Ni2+-poly[d(A-T)].poly[d(A-T)] films are analyzed by comparison with previously assigned IR spectra of left-handed poly[d(G-C)].poly[d(G-C)] and poly[d(A-C)].poly[d(G-T)], and it is possible to conclude that they reflect a Z-type structure for poly[d(A-T)].poly[d(A-T)]. The Z conformation has been favored by the high polynucleotide concentration, by the low water content of the films, and by specific interactions of the transition metal ions with the purine bases stabilized in a syn conformation. A structuration of the water hydration molecules around the double-stranded Ni2+-poly[d(A-T)].poly[d(A-T)] is shown by the presence of a strong sharp water band at 1615 cm-1.

Infrared spectral studies of the non regularly alternating purine-pyrimidine hexamers d(m5CGGCM5CG), d(CBr8GGCCBr8G) and d(CGCGGC).

The oligonucleotides d(m5CGGCm5CG), d(CBr8GGCCBr8G) and d(CGCGGC) have been prepared and studied by infrared spectroscopy. The three sequences contain two GC pairs which are out of purine-pyrimidine alternation with the rest of the sequence. From the IR data of the d(m5CGGCm5CG) hexamer, it is shown that all of the dG residues adopt a syn conformation. The marker IR bands for the C3' endo syn conformation are at 1410, 1354, 1320 and 925 cm-1 whereas those for the C2' endo anti conformation at 1420, 1374 and 890 cm-1 are clearly absent. This result implies that the two adjacent guanines of the d(m5CGGCm5CG) sequence are in syn conformation. It is suggested that duplex formation occurs in d(CGCGGC) films and that all of the guanines are in syn conformation. In contrast, the central non-brominated guanine of the d(CBr8GGCCBr8G) hexamer is found in anti conformation, as expected in a Z type structure of the non-alternating region.

NMR, CD and IR spectroscopies of a tridecanucleotide containing a no-base residue: coexistence of B and Z conformations.

The synthesis of the tridecadeoxynucleotide d(CGm5CGCGxACATGT), where x is the 1-cyano-2-deoxy-beta-D-erythropentofuranose, is described. The NMR, IR, CD studies at various salt concentrations and temperatures of this oligomer show that the B and Z conformations are simultaneously present in the same short DNA fragment. A single apurinic residue is sufficient for the coexistence of the B and Z helices on this oligomer.

Right-handed and left-handed helices of poly(dA-dC) X (dG-dT).

The secondary structures of poly(dA-dC) X (dG-dT) were studied using CD and IR spectroscopies. We give spectroscopic evidence of secondary structure transitions of poly(dA-dC) X (dG-dT) from a B to a Z-like helix, induced by transition metal ions (Ni2+) in presence of high concentrations of Cs+ and Na+. In the presence of Na+, the B in equilibrium Z transition occurs at any temperature, whereas premelting conditions are required in presence of Cs+. For these two alkali ions the Z-like form is only induced by Ni2+ ions through their specific interactions at N7 of purines, under conditions of low water activity due to the high alkali salt concentration. We also show that the CD spectrum obtained in presence of Cs+ ions and characterized by a negative band at 275 nm, cannot be interpreted in terms of Z-like left-handed helix but reflects a modified B right-handed helix.

Z helix-coil transition of d(C-Br8G-C-G-C-Br8G) studied by CD, 1H-NMR and IR spectroscopies.

The conformation of d(C-Br8G-C-G-C-Br8G) in aqueous solution was studied by CD and 1H-NMR spectroscopy and in condensed phase by IR spectroscopy. Whether in 0.1 M or 3 M NaCl solution or in film the only double helical structure adopted by brominated d(C-G)3 oligomer is the Z form. The IR spectrum of the film presents all the characteristic absorptions of the Z conformation and in particular is indicative of a syn conformation for the central guanosine as well as for the brominated one. Imino proton resonances of d(C-Br8G-C-G-C-Br8G) demonstrating the duplex formation were observed up to 60 degrees C. It is interesting to note that the significant highfield shifts of the dC H5" exocyclic sugar protons characteristic of the non exchangeable proton spectra of d(C-G)3 containing 5-methyl dC residues in the Z form were also detected in the proton spectrum of brominated oligomer. Whereas formation of the Z helix of methylated d(C-G)3 oligomers dependent on the salt concentration was found to occur via the preliminary formation of a B helix even in 4 M NaCl solution, the Z helix of d(C-Br8G-C-G-C-Br8G) is obtained directly from the coil form. However, IR data suggest that in the Z form of d(C-Br8G-C-G-C-Br8G), the overlapping of the base planes should be slightly different in comparison with the stacking observed in d(C-G)3 crystals. The kinetic data (activation energy and lifetime) of the Z helix-coil transition of brominated d(C-G)3 are compared to those of the B helix-coil transition observed for methylated d(C-G)3 in 0.1 M NaCl solution while the thermodynamic data of these two reactions (enthalpy and midpoint temperature) are slightly different.