Biomedical subjects
Publications and source records attributed to F C Laing.
The authors have successfully diagnosed medullary cystic disease on the basis of the sonographic and computed tomographic appearances of the characteristic small cysts. The disease is described and its differential diagnosis is considered.
The ultrasonographic findings in two patients with peptic ulcer disease and one patient with acute pancreatitis are reported. In each case, the sonographic appearance simulated intrinsic gallbladder disease. Two patients had focal pericholecystic fluid collections and one had an inflammatory mass adjacent to the gallbladder. Each patient also demonstrated gallbladder wall thickening. Findings of a pericholecystic fluid collection or an inflammatory mass adjacent to the gallbladder appear to be nonspecific for cholecystitis, and should also suggest inflammation of adjacent organs.
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Despite the common occurrence of regenerating liver nodules, little has been written regarding their ultrasound or computed tomographic appearance. In the great majority of cases, they have an echo texture and CT number identical to surrounding hepatic parenchyma. Exceptionally, as in the 2 cases described, they can mimic a malignant neoplasm. Because radionuclide imaging almost always demonstrates uptake over a regenerating nodule, this modality should be used in suspicious cases in conjunction with either ultrasound or computed tomography in order to exclude a malignancy.
Five cases of recurrent pyogenic cholangitis (RPC) were studied by ultrasonography, computed tomography (CT), and cholangiography. All patients were recent immigrants from the Orient or Indonesia and had had recurrent attacks of cholangitis for many years. The bile was infected by E. coli and the biliary ducts were dilated; in addition, extrahepatic bile-pigment calculi were present in all 5 and intrahepatic calculi in 4. Abdominal ultrasound usually failed to demonstrate duct calculi and extrahepatic dilatation due to the soft, mud-like consistency of the stones. CT was successful in showing the calculi and the full extent of dilatation. The authors conclude that preoperative diagnosis of RPC is best achieved by awareness of the characteristic clinical presentation and the findings on abdominal CT. Preoperative cholangiography provides excellent detail, but poses the danger of biliary sepsis requiring antibiotics.
The sonograms of 34 patients with surgically proved pelvic hemoperitoneum were reviewed. In 15 of these patients clotted blood was found at surgery in the pelvis or cul-de-sac. In nine of these patients (60%), ultrasound demonstrated echogenic fluid collections or "masses" with an echogenicity equal to or greater than the uterus. Because anechoic fluid in the pelvis is a nonspecific finding, awareness that clotted blood can be highly echogenic may be of considerable value in the differential diagnosis of pelvic fluid collections. The limitations and pitfalls in interpreting this finding are discussed.
Transducer side lobes consist of multiple low-intensity sound beams located outside of the main ultrasound beam. Although the echoes generated by side lobes originate outside of the main beam, they appear as specular or diffuse artifactual echoes within the beam. They are visible with both static and real-time equipment. Specular side-lobe artifacts occur near strong, curved, highly reflecting surfaces such as the diaphragm, or near large cystic masses such as the urinary bladder or gallbladder. Diffuse artifacts originate from bowel gas adjacent to cystic structures. These echoes can be confused with particulate material or sludge in organs such as the urinary bladder and gallbladder, or in abnormal cystic masses. We illustrate the genesis of these artifactual echoes and provide clinical examples of commonly visualized side-lobe artifacts.
With high-resolution real-time sonography it is possible to visualize normal fetal cardiovascular structures in a high percentage of second- and third-trimester pregnancies. At present the optimal view for cardiac visualization is the four-chamber view, which affords simultaneous imaging of the atria, ventricles, and atrioventricular and interventricular septa. The fetal aortic arch can be readily demonstrated in most patients. The most significant factor limiting cardiac examination is fetal position, since it is extremely difficult to scan prone fetuses. High-resolution real-time sonography has the potential to permit in utero diagnosis of major structural cardiac anomalies and should become part of the routine ultrasound screening for congenital anomalies.
The combined use of a serum radioimmunoassay pregnancy test and high resolution utrasonography allows a more direct approach to be made in the diagnosis of ectopic pregnancy. It is important for ultrasonographers to understand the limitations of the more readily available immunologic pregnancy tests in order to avoid misinterpreting ultrasonograms in the event that a pregnancy test is either falsely positive or falsely negative. Clinical suspicion is mandatory if the early diagnosis of ectopic pregnancy is to be made. The referring physician should take advantage of the highly accurate information resulting from the combined findings of a positive serum HCG and the ultrasonographic images. If the statistics regarding diagnostic delay and tubal rupture are to be improved, these tests should be obtained when a patient is initially evaluated. It is important to recognize that the ultrasonographic interpretation rests primarily upon the uterine findings. A normal viable intrauterine pregnancy essentially excludes the diagnosis of ectopic pregnancy. Other uterine appearances may result from an early intrauterine pregnancy, an abnormal intrauterine gestational event, or, as in approximately 1 per cent of pregnancies, an ectopic gestation. Subsequent evaluation in suspicious cases may require a variety of tests including serial HCG determinations, repeat ultrasound examination, uterine dilatation and curettage, culdocentesis, or laparoscopy. It is impossible to recommend a specific schematic approach for any given patient. In part, the pattern of management depends upon availability of tests, the presence or absence of adnexal or cul-de-sac findings, and, of course, the clinical status of the patient.U
A retrospective analysis of 102 patients with clinically suspected placenta previa revealed that ten women (10%) were correctly diagnosed as having placenta previa, while two women (2%) had false-positive diagnoses. Three of the ten women who were correctly diagnosed as having placenta previa had scans that could easily have been misinterpreted as normal. Because a false-negative diagnosis of placenta previa is clinically much more serious than a false-positive diagnosis, these cases are elaborated upon. Recognition of a laterally positioned placenta previa and observation of blood in the region of the internal cervical os should minimize false-negative diagnostic errors.
The oblique bending projection, when incorporated into routine radiographs during oral cholecystography, was found to be at least as effective as fluoroscopic spot radiographs in obtaining information about the gallbladder.
A case of a postcholecystectomy patient is presented in which an initially grossly dilated common hepatic duct returned to normal size within several minutes. We have tried to explain this phenomenon using known facts abut bile duct elasticity and bile flow, and conclude that such rapid size change probably only occurs in those patients without a normally functioning gallbladder.
To define the role of ultrasound in evaluating acute right upper quadrant pain, a prospective study was performed on 52 patients having clinically suspected acute cholecystitis. Ultrasonographic determination of acute or chronic cholecystitis, or diagnosis of a normal gallbladder, was based on analysis of location of tenderness, calculi, sludge, and wall thickness. The diagnosis of acute cholecystitis (34.6% of patients) was based on the highly significant observations of focal gallbladder tenderness and calculi. Sludge and wall thickening were also statistically significant, but to a lesser degree. Cholelithiasis allowed differentiation of patients with chronic cholecystitis (32.7%) from patients with normal gallbladders (32.7%). Neither of these two groups had significant focal gallbladder tenderness, sludge, or thickened walls. Because acute cholecystitis is found in the minority of patients with acute right upper quadrant pain, and because ultrasound is rapid, accurate, and noninvasive, it should be the initial modality used to evaluate these patients.
Fifty patients with abdominal trauma and possible splenic injury were evaluated by computed tomography (CT). CT correctly diagnosed 21 of 22 surgically proved traumatic lesions of the spleen (96%). Twenty-seven patients had no evidence of splenic injury. This was confirmed at operation in 1 patient and clinical follow-up in 26. There were one false negative and one false positive. In 5 patients (10%), CT demonstrated other clinically significant lesions, including hepatic or renal lacerations in 3 and large retroperitoneal hematomas in 2. In adolescents and adults, CT is an accurate, noninvasive method of rapidly diagnosing splenic trauma and associated injuries. Further experience is needed to assess its usefulness in evaluating splenic injuries in infants and small children.
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In later stages of pregnancy, acoustic shadowing from a fetal head may obscure the termination of a low-lying placenta and prevent sonographic imaging of the internal cervical os. The evaluation of a marginal or partial placenta previa in this setting may be difficult. Placing the mother in Trendelenburg position and applying gentle upward traction on the fetal head allows amniotic fluid to cover the lower uterine segments. This provides an acoustic window to visualize the relation of the termination of the placenta to the internal os. This technique was evaluated prospectively in a series of 217 patients and was successful in 49 of 50 patients in whom conventional studies failed to image the termination of the placenta or the region of the internal os.
Ultrasonograms of 45 patients with 51 surgically proved benign cystic teratomas (dermoid cysts) of the ovary were reviewed to evaluate the ultrasonographic appearance of this entity. Contrary to several recent reports stressing a "typical" appearance for ovarian dermoid cysts, ie, an echogenic focus with acoustic shadowing situated within a predominantly cystic mass, the authors observed a much broader spectrum of appearances. Thirty-three percent of the cases demonstrated "typical" findings, 23.5% were predominantly solid, 20% were almost entirely cystic, and 23.5% were not visible. Ultrasound and conventional radiography in patients with dermoid cysts were compared: Ultrasonography contributed significantly to the correct diagnosis in the majority of cases. Because ultrasonography lacks ionizing radiation, and its use may reveal unrelated pelvic pathology, it should be the initial diagnostic modality in the examination of patients with suspected dermoid cysts of the ovary.
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