Cook macaroni according to package directions. Drain; set aside. Combine salmon, yogurt, cucumber, carrot, mayonnaise or salad dressing, dillweed, 1/4 teaspoon salt and 1/4 teaspoon pepper. Toss with pasta. Cover, chill 4 to 24 hours.
Meanwhile, for tomato cups, cut out 1/2 inch of the core from each tomato. Invert tomatoes. For each, cut from top to, but not quite through the stem end, making 6 wedges.
To serve, place tomatoes on plates. Spread wedges slightly apart; fill with salmon pasta mixture. Makes 4 servings.
Nutrition information per serving: 186 calories, 15 g protein, 19 g carbohydrates, 6 g fat, 3 mg cholesterol, 452 mg sodium, 570 mg potassium