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Metal objects present in x-ray computed tomography (CT) scans are accompanied by physical phenomena that render CT projections inconsistent with the linear assumption made for analytical reconstruction. The inconsistencies create artifacts in reconstructed images. Metal artifact reduction algorithms replace the inconsistent projection data passing through metals with estimates of the true underlying projection data, but when the data estimates are inaccurate, secondary artifacts are generated. The secondary artifacts may be as unacceptable as the original metal artifacts; therefore, better projection data estimation is critical. This research uses computer vision techniques to create better estimates of the underlying projection data using observations about the appearance and nature of metal artifacts.The authors developed a method of estimating underlying projection data through the use of an intermediate image, called the prior image. This method generates the prior image by segmenting regions of the originally reconstructed image, and discriminating between regions that are likely to be metal artifacts and those that are likely to represent anatomical structures. Regions identified as metal artifact are replaced with a constant soft-tissue value, while structures such as bone or air pockets are preserved. This prior image is reprojected (forward projected), and the reprojections guide the estimation of the underlying projection data using previously published interpolation techniques. The algorithm is tested on head CT test cases containing metal implants and compared against existing methods.Using the new method of prior image generation on test images, metal artifacts were eliminated or reduced and fewer secondary artifacts were present than with previous methods. The results apply even in the case of multiple metal objects, which is a challenging problem. The authors did not observe secondary artifacts that were comparable to or worse than the original metal artifacts, as sometimes occurred with the other methods. The accuracy of the prior was found to be more critical than the particular interpolation method.Metals produce predictable artifacts in CT images of the head. Using the new method, metal artifacts can be discriminated from anatomy, and the discrimination can be used to reduce metal artifacts.

A case of repeated ruptured tubal pregnancy with secondary abdominal implantation which simulated a case of low ileal obstruction is here presented. The incidence of repeated ectopic gestations is discussed, and the importance of examination of the opposite tube is emphasized in determining the operative procedures to be carried out at the time of operation. The reasons for the clinical findings in this case are mentioned with the aim of emphasizing the importance of shoulder pain, jaundice, midline colicky pains, together with vomiting, distention and obstipation, in the diagnosis of the obscure case of the less dramatic type of ectopic pregnancy. I take this opportunity of thanking Dr. John E. Jennings for the privilege of presenting this case, and Dr. Chester L. Davidson, on whose service the case was followed.

1. 1. The history of generalized peritonitis secondary to ruptured pyosalpinx is briefly reviewed. 2. 2. Although not a common complication of gonorrhea in the female, rupture of a pyosalpinx accounts for 8 per cent of all cases of generalized peritonitis. 3. 3. In the majority of cases of spontaneous rupture of a pyosalpinx, there is no assignable cause for the perforation. There is no strict correlation between perforation and the number of acute attacks of salpingitis or the size of the pyosalpinx. 4. 4. The diagnostic features consist of a sudden onset of a diffuse and rapidly spreading peritonitis associated with a state of circulatory collapse, followed by a rapidly rising temperature, a leucocytosis and an elevated erythrocyte sedimentation rate. 5. 5. The treatment of choice of this condition is a bilateral salpingectomy followed by the insertion of a Mickulicz' or tube drain into the pelvis. 6. 6. The prognosis depends upon the general state of the patient, the time of surgical intervention, the nature of the operation instituted, and to a lesser extent, the bacteria present at the time of perforation. 7. 7. Two cases of generalized peritonitis secondary to spontaneous rupture of a pyosalpinx are here presented and discussed.

This study is based on a series of fifty cases of perforated peptic ulcer treated at the Cumberland Hospital during a seven year period from 1931 to 1937. The average age of these fifty male patients was thirtynine years. There appears to be a seasonal incidence for the occurrence of this condition. The majority of cases occurred in the fall months of September, October and November. Most of these patients had a definite history of peptic ulcer symptoms for an average duration of three and onehalf years prior to perforation. The history of a sudden, sharp, severe abdominal pain followed by radiation of the pain to the shoulders appears important in the diagnosis of this condition. Objectively, the presence of marked abdominal tenderness, and rebound tenderness, with board-like rigidity of the abdominal muscles, and obliteration of liver dulness with a definite leucocytosis, make the diagnosis of the case conclusive. The most important factor in determining the outcome is the interval of time between perforation and operation. The mortality rises sharply as this length of time increases. The simplest of operative procedures, namely, aspiration of the fluid and closure of the perforation, carried out with the least additional trauma is the procedure indicated. Generalized peritonitis appears to be the cause of death in a majority of the fatal cases. It appears unlikely that this may be influenced in any way, by delaying operation to improve the patient's condition, or by changing the operative procedure. A follow-up study of 73 per cent of the cases revealed that most of the patients were entirely free of symptoms, at an average of one and one-half years following the perforation.

In the past few years a voluminous literature has appeared on the subject of stricture of the rectum secondary to lymphogranuloma venereum. Almost without exception, however, the treatment of this condition has been dealt with superficially and briefly. The obvious reason for this has been the inadequacy of all forms of treatment instituted. An utter feeling of despair has arisen in both patient and physician, so that permanent colostomy has been accepted as the procedure of choice. What a high price this is for the young adult afflicted with an otherwise benign condition that can be reached with the finger! And no hope was entertained by these patients of ever having these colostomies closed after any local form of treatment to the strictured areas. Ault 1 in his review of venereal diseases of the rectum states that "No permanent cure of stricture due to lymphogranuloma venereum has been reported to

The purpose of this paper is to call attention to a not infrequent and often overlooked pathologic state occurring in patients subjected to a loss of gastric or high intestinal secretions over a long period. In medical and surgical wards such patients are frequently seen presenting symptoms of pyloric or high intestinal obstruction or being subjected to continuous gastric or intestinal drainage for the alleviation of distention and vomiting. The alarming clinical picture these patients present is frequently overlooked, and effective treatment of the condition is too often lacking. The patients, therefore, are permitted to succumb to a chemical acid-base imbalance, with its accompanying impaired renal function. At autopsy, they are often found to have extensive and apparently irreparable renal calcification. The early institution of proper therapy in such cases might often forestall this outcome, for the restoration of a proper chemical balance might restore or markedly improve the function