Manganese dipyridoxyl diphosphate. Effect of dose, time, and pulse sequence on hepatic enhancement in rats.

We used an animal model to investigate the hepatic enhancement characteristics of manganese dipyridoxyl diphosphate (MnDPDP) related to time, dose, and pulse sequence. The contrast doses selected were in the human tolerance range. Using an SE 300/15 pulse sequence, maximum mean hepatic enhancement of 45% (8 mumols/kg) and 58% (12 mumols/kg) over baseline was seen during a plateau maintained between 5 and 50 minutes postinjection in the 8 mumols/kg group, and between 10 and 90 minutes in the 12 mumols/kg group. This plateau was followed by a very gradual decline in hepatic enhancement. Using either 4 or 8 mumols/kg, there was a significant increase in postcontrast hepatic intensity on all relatively T1-weighted pulse sequences (spin echo [SE] 300/15, inversion recovery [IR] 1400/20/400, gradient echo [GE] 47/13/80 degrees, and GE 60/20/30 degrees) except GE 47/13/80 degrees at 4 mumols/kg. At 8 mumols/kg there was superior enhancement, with IR 1400/20/400 and SE 300/15, but at 4 mumols/kg there was no consistently superior sequence. None of the relatively T2-weighted pulse sequences (SE 2000/50, SE 2000/100, or GE 100/30/20 degrees) demonstrated a significant change in hepatic intensity using either dose of contrast. The data suggest that the best combination of dose, pulse sequence, and time for hepatic imaging with MnDPDP is 8 mumols/kg using heavily T1-weighted sequences 5 to 60 minutes following contrast administration.

Thoracic findings in gastrointestinal pathology.

A large variety of gastrointestinal and abdominal pathologic processes can be diagnosed or suspected by their direct effects on the chest. The chest radiograph, as often the first admission film, can aid the radiologist in recommending the appropriate follow-up examinations.

Lymphomatous esophageal nodules: the difficulty in radiological differential diagnosis.

A case of lymphomatous infiltration of the esophagus presenting as diffuse nodularity on double contrast esophagography is presented. This report is a reminder to the radiologist and clinician of the varied roentgen manifestations of many entities involving the esophagus in the immunocompromised patient and the difficulty in radiological differential diagnosis.

Aphthous lesions in nodular lymphoma of the colon.

The umbilicated nodules in colonic lymphoma may simulate aphthous ulcers of inflammatory or infectious colitides. Our report illustrates that in an immunosuppressed patient it may be difficult to distinguish on double contrast barium enema between the aphthous ulcers of opportunistic colitis and the umbilications of nodular colonic lymphoma.

Focal hepatic lesions: detection by dynamic and delayed computed tomography versus short TE/TR spin echo and fast field echo magnetic resonance imaging.

Eighteen patients with focal hepatic lesions were evaluated with two computed tomographic (CT) techniques including dynamic sequential bolus contrast CT and delayed contrast CT, and 3 magnetic resonance (MR) techniques including a spin echo pulse sequence with TE/TR of 21/310 msec and 2 fast field echo sequences using a TE/TR of 15/300 msec and 80 degrees flip angle (T1-weighted) and TE/TR of 15/500 msec and 10-20 degrees flip angle (T2-weighted). We concluded that CT, using delayed contrast and dynamic sequential bolus contrast techniques, was consistently superior to the 3 MR pulse sequences used on our imagers in terms of number of lesions detected, lesion-to-liver contrast, and quality of scan.

Imaging guided percutaneous hepatic biopsy: diagnostic accuracy and safety.

During the 3-year period from May 1981 to June 1984, 145 patients with hepatic abnormalities demonstrated by computed tomography (CT) or ultrasonography (US) underwent 151 imaging guided percutaneous hepatic biopsies. These biopsies were performed with needles ranging in size from 21-gauge aspiration to 14-gauge cutting type. Histologic and cytologic results were correlated with subsequent surgical, autopsy, and clinical follow-ups ranging from 2 months to 3 years. The overall accuracy for imaging-guided biopsies was 92.1% and 98% for diagnosis of malignant lesions. Our complication rate of 1.3% is comparable to that reported in other studies. We discuss indications, techniques, and risks for imaging-guided percutaneous hepatic biopsy.

Delayed hepatic CT scanning: increased confidence and improved detection of hepatic metastases.

Fifty oncologic patients with suspected hepatic metastases were prospectively evaluated by dynamic sequential hepatic computed tomography (DSHCT) and by delayed iodine hepatic computed tomography (DICT) scanning. DICT scanning was performed 4-6 hours following administration of 60 g of intravenous iodine. Both techniques were evaluated for lesion definition relative to the adjacent hepatic parenchyma and for numbers of metastases detected. Metastases were detected by both techniques in 26 patients. Fifteen patients (58%) had lesions better defined by DICT. DICT scanning detected more metastases in seven of these 15 patients. In eight patients (31%), there was no difference between the two techniques in numbers of masses detected or lesion definition. In three cases (11%), metastases were more confidently identified on the initial or DSHCT scan. DICT scanning, as described, is useful in defining and detecting hepatic metastases, especially where there is questionable hepatic involvement or better quantification of size is necessary.

Percutaneous needle biopsy in the diagnosis and classification of lymphoma.

Results of percutaneous needle biopsies were evaluated retrospectively in 58 patients in whom a diagnosis of lymphoma was suspected. The biopsy specimen was diagnostic in 94% of the 36 patients with lymphoma, 20 of whom had recurrent disease and 16 of whom had newly diagnosed lymphoma. Sufficient tissue was obtained in 94% of these positive biopsy specimens to allow histologic subtyping of the lymphoma. Immunohistochemical studies performed on seven of the biopsy specimens allowed immunologic subclassification into B-cell and T-cell types of lymphoma. Our results suggest that the percutaneous needle biopsy is a useful and reliable tool in the diagnosis and classification of lymphoma.

Shunts for portal hypertension: MR and angiography for determination of patency.

Twenty-eight patients with selective and nonselective shunts for portal hypertension were evaluated using magnetic resonance (MR) imaging. Angiographic correlation was obtained in 25 patients. MR imaging enabled the detection of a patent shunt by visualizing the "flow void" phenomenon in 21 patients. Two patients had thrombosed shunts. In these 23 patients, there was no discrepancy between the findings from MR imaging and those from angiography. In the remaining five patients, there was an area of artifact in which no signal was noted, and the shunt could not be evaluated. In all five patients who had this artifact, steel coils were noted in the area of the phenomenon. Thus, MR imaging seems to be an accurate method for detecting shunt patency in all patients with shunts except those who have had prior embolization with steel coils.